Here - National Seed Industry Council

1

P R E F A C E

The Root Crops Varietal Improvement Group (also called Root Crops Technical

Working Group or RTWG) of the Philippine Seed Board (now National Seed Industry

Council) was organized in 1981. One of the first activities of this group was to formulate

guidelines/procedures for the conduct of regional trials of root crops. A guide for

conducting varietal evaluation of sweetpotato, cassava, yams (ubi and tugui), and gabi

was prepared and distributed to the different cooperating stations. That early set of

directions for conducting root crops variety trials emphasized the field plot techniques

and cultural practices to be followed for each of the crops mentioned. However,

procedures to rate pests commonly observed in these crops as well as procedures to

evaluate characters related to quality such as root dry matter and starch contents are

lacking.

To come up with a set of procedures for conducting the national cooperative trials

for root crops that will cover all aspects of variety testing with modified field plot

techniques and more reliable results, a training-workshop participated by the RTWG

members was held at the Philippine Root Crops Research and Training Center, VISCA

Baybay, Leyte on 27-28 April 1993. The output of the training workshop was further

discussed and modified during subsequent RTWG meetings. This manual on

Standardized Techniques for Root Crop Evaluation is, thus, a product of the combined

efforts of past and present members of the RTWG.

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TABLE OF CONTENTS

Preface

Procedure for Specific Crop Evaluation

Cassava -------------------------------------------------------------------

Sweetpotato -------------------------------------------------------------------

Gabi -------------------------------------------------------------------

Ubi and Tugui -------------------------------------------------------------------

Potato -------------------------------------------------------------------

Procedure for Rating of the Different Root Crop Anthropod Pests

Cassava -------------------------------------------------------------------

Sweetpotato -------------------------------------------------------------------

Gabi -------------------------------------------------------------------

Ubi and Tugui -------------------------------------------------------------------

Potato -------------------------------------------------------------------

Procedure for Rating Different Root Crop Diseases

Cassava -------------------------------------------------------------------

Sweetpotato -------------------------------------------------------------------

Gabi -------------------------------------------------------------------

Ubi and Tugui -------------------------------------------------------------------

Potato -------------------------------------------------------------------

Standard Method of Preparing Root Crops Sample for:

Dry Matter and Starch Determination ---------------------------------------

Rapid Evaluation of Cyanide Content of Cassava Roots -----------------

Techniques in Sensory Evaluation -------------------------------------------------

Importance of Uniform Field Plot Techniques in the Conduct

of Variety Trials ----------------------------------------------------------

Appendix Forms -------------------------------------------------------------------

Appendix Tables -------------------------------------------------------------------

List of Participants -------------------------------------------------------------------

3

PROCEDURE FOR CASSAVA EVALUATION TRIALS

General Procedure

Choice of Land. Select an area which is well drained and more or less uniform in

fertility and slope. Ideally, use an area for one cassava cropping only. However, if land is

limited, at most two cropping evaluations may be done in the same area. Only areas

previously used for trials with uniform cultural management can be used for varietal

evaluation. Control soil facility evaluation to the minimum.

Land Preparation. Plow the area twice when carabao drawn implement is used.

Afterwards, harrow twice at one week interval. One plowing and one harrowing may be

sufficient when tractor-drawn plow and harrow are used. After the last harrowing,

construct ridges 1.0 m apart.

Experimental Design. Use the randomized complete block design (RCBD) with

four (4) replications.

Size of Plot. The plot for each entry should have five (5) rows. Each row should

be 4.5 m long and spaced 1 m apart. The hills should be spaced at 0.75 m.

Plot Layout. Ensure that a replication (block) is as square as possible. The

difference between the length and width of the block must be minimized. Ideally all

blocks must be contained in one contiguous area. However, if a contiguous area to

accommodate the four replicates is not available, separate the blocks such that each block

will contain all the etries. A sample layout for a 12-entry trial is shown in Figs. 1-5.

Border Rows of the Experimental Area. To safeguard the experimental area

from grazing animals and other invading mammals, place at least two border rows on

each side and at least two hills on each end of the area.

Planting Materials. Select stems from at least 7 month-old cassava plants that

are free from insect pests and diseases. Cut into 20 cm long stakes for planting.

Pre-planting Treatment. To ensure that the planting materials are free from

scale insects, soak them in any systemic insecticide such as tamaron or silicrone. If stakes

are infected with fungus, soak them in fungicide.

Planting Time. The specific schedule for planting will be discussed during the

annual NCT meeting. However, the planting period for each year must be from May to

early July.

Replanting. If missing hills are present, replant not later than 2 weeks after

planting.

4

Planting Method. Plant the stakes vertically at the crest of ridges with two-thirds

(2/3) of the length buried in the ground.

Fertilizer Application. Have the soil in each site analyzed. Adjust the fertilizer to

be applied to the rate of 60-60-60 kg N, P2O5, K2O per hectare. Apply the fertilizer

basally on a per row basis at 10 cm from the plant base towards the side of the ridge.

Fertilize at planting or within 2 weeks after planting.

Irrigation. When irrigation water is available, irrigate the plants during long dry

spells especially during the first 3 months of the growing season.

Pest Control. Depending on pest incidence and severity, apply appropriate

pesticide whenever necessary. Before applying control measures, be sure to take the

incidence and severity ratings.

Weed Control. Control weeds regularly during the first 2 months after planting.

After this, weed only when necessary.

Harvesting. Harvest at 8-10 months after planting. Specify on the data sheet the

age of the plant at harvest. In each plot, harvest the three middle rows except the end

hills. Record the actual number of hills harvested per plot.

After lifting and separating the roots from the stem, remove/scrape off adhering

soil. Classify storage roots having at least 3 cm in diameter as marketable and those

below 3 cm in diameters as non-marketable. Weigh the storage roots according to class.

Data to be gathered:

1. Field Stand – Record the number of plants in the three middle rows per entry,

excluding end hill, at 2 weeks after planting and at harvesting. Ideally, there

should be 12 plants/hills per plot.

2. Dry Matter Content – Do actual dry matter analysis for selected stations and use

specific gravity method for the rest.

3. HCN Content – Determine this in selected stations only.

4. Length of Peduncle – Measure the peduncle (in cm) of all roots in one randomly

selected hill in each replication.

5. Lodging – Use the rating scale of 1, 5 and 9 (Rating must be done at harvest).

Lodging 1 – no lodging (straight)

5 – medium lodging

9 – heavy (total) lodging

5

6. Rating for Pests – Rate the incidence first at 2 months after planting, then at

bimonthly interval and lastly at 1 month before harvest. Use five randomly chosen

sample plants from three replications.

7. Sensory Evaluation – This will be done in selected stations only. Acceptability

and eating quality scores of sweet varieties only will be taken.

8. Marketable Yield – Consider all usable roots, at least 3 cm in diameter, that can

be sold in local market. Count and weigh them on per plot basis.

9. Non-marketable Yield – Consider all roots which are not worth selling although

may be used as animal feeds. Count and record their number and weigh them.

10. Total Yield – Add the weights obtained in nos. 7 and 8 to get the total root weight

per plot basis.

11. Remarks – Record any other observations considered pertinent such as soil and

agroclimatic data.

The formula and procedure in calculating yield are given below.

Yield (ton/ha) = Yield in kg/plot x 1.1111

In yield calculation, consider only plots with at least 10 hills. Result from an entry

with less than three replications should not be included for that location test.

SAMPLE FIELD LAYOUT FOR A 12 ENTRY CASSAVA TRIAL

Number of entries : 12

Number of replications/blocks : 4

Plot size : 5 row with 6 hill for each row starting from

the end

Planting distance : 0.75 m x 1 m (3.75 m from end hill to end

hill

Harvestable area : 3 rows with 4 hills per row (12 inner hills)

Border rows around the experimental area : At least two rows on each side of the area

6

Alley way : 1.5 m between sub-blocks (3 sub-blocks per replication)

Figure 1. Contiguous block allocation when an experimental area can accommodate

all four replications. The experimental area is almost square.

Alleyway : 1.5 m between sub-blocks

Figure 2. An alternate blocking when an area allotted for the trial is long and can

accommodate all four replicates.

20 m

14.25

m Block I

Block IV Block II

Block III

Border

Rows

20 m

14.25m 14.25m 14.25m 14.25m

Block I Block II Block III Block IV

7

14.25m

Border Row

Border Row

Area A

Area B

Alleyway: 1.5 m between sub-blocks

Figure 3. If only 3 blocks can be accommodated in Area A, the fourth block may be

constructed in another site, Area B. However, each block must contain the

same entries. Also, two blocks may be located in Area A and the other two

in Area B. However, border rows must be placed around the perimeter of

the experimental area, even when blocks are separated.

Block I 20 m

14.25m 14.25m

Block II Block III

Block IV

20 m

8

Figure 4. Each plant has an effective area of 0.75 sq. m.

A: Plot (P) distribution in each block

14.25 m

* * * * *

* * * * *

* * * * *

* * * * *

* * * * *

* * * * * P2 P3 P4

P8 P7 P5

P9 P10

P6

P11 P12

20 m

5 m 5 m 5 m 5 m

3.75 m

3.75 m

3.75 m

1.5 m

1.5 m

9

Figure 5. How each plot should look. Each * corresponds to a plant. The harvestable

area is enclosed in the rectangle (effective plot area is 9 m square)

* * *

*

*

*

*

*

*

*

*

*

*

* * *

* * *

* * *

* *

* * *

* * *

1.5 m

0.75 m

3.75 m

11

NRCCTP Form No. 1

NATIONAL ROOT CROP COOPERATIVE TESTING PTOGRAM

CASSAVA REGIONAL TRIAL

LOCATION: ___________________________ PLANTING DATE: _____________

SEASON: ___________________________ HARVEST DATE: _____________

Plot

No.

Rep.

No.

Entry

Name

Maturity Survival

Rate

Lodging

Resistance

Number

of Plants Harvested

No. of Roots Wt. of Roots/Plot (kg) Starch

Content

Dry

Matter Content

HCN

Content

Pest/Disease Rating Remarks

Marketable Non-

Marketable

Marketable Non-

Marketable

Scale Mites CBB

NRCCTP Form No. 2

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DATA SUMMARY FOR CASSAVA EVALUATION TRIAL

Plot

No.

Entry Name No. of

Plants Harvested

Dry

Matter Content

HCN

Content

Lodging

Rating

Acceptability

Score

Pest and Disases Weight and Number/Plot or Hectare Remarks

Mite CBB No. Wt. No. Wt. No. Wt.

13

PROCEDURE FOR SWEETPOTATO EVALUATION TRIALS

General Procedure

Choice of Land. Select an area which is well-drained and more or less uniform in

fertility and slope. Use an area for one sweetpotato cropping only. However, the same

area can be planted again to sweetpotato if fallowed for at least 4 months or planted to

other crops. Only areas previously used for trials with uniform cultural management can

be used for varietal evaluation. Soil fertility variation must be minimized.


Two harrowings at one week interval should be done after. One plowing and one

harrowing maybe sufficient when tractor drawn plow and harrow are used. After the last

harrowing, construct ridges 1.0 m apart.


at least four (4) replications.

Size of Plot. Each plot must have two rows, each measuring 6 m x 2 m. Space

between rows should be 1 m.

Number of Entries. Entries for each trial should not exceed 16 test cultivars

including checks.

Planting Distance. In each row, space the plants at 30 cm between hills.

Field Layout. Make each replication/block as square as possible. An example of

blocking for a 16 entry trial is shown in Figure 7. It is best to set sub-blocks 1.0 m apart

(i.e., each alleyway will be 1.0 m wide)/

Border Rows of the Experimental Area. Provide at least two rows in each side

and at least seven border hills on each end of the area. There should be no border rows or

vacant spaces between sub-blocks except between replications.

Planting Materials. Planting materials for the trial must be 25 cm long tip vine

cuttings. If terminal cuttings are insufficient, secondary cuttings may be used provided

that these materials will be planted in separate blocks. Set aside a separate area for the

multiplication of planting materials. Clip expanded leaves of materials which will be

transported from one station to another.

Pre-planting Treatment. For pest control, pre-planting treatment with a

fungicide- insecticide mixture maybe done whenever necessary.

Planting Method. Plant on the ridges leaving about 6 cm of the tip of the cutting

above the ground. Distance between hills should be 30 cm. Plant only 1 cutting per hill.

14

Re-planting. Replant missing hills within one week after planting.

Fertilizer Application. Have the soil in each site analyzed. Adjust the fertilizer

rate to be used based on the recommended rate of 45-45-45 kg/ha of N, P2O5 and K2O.

Apply fertilizer basally on a per row plot basis at 10 cm from the base of the ridge at

planting time. Fertilizer should be applied only during the dry season, none during the

wet season.

Irrigation. Where irrigation water is available, irrigate whenever necessary.

Pest Control. To control insect pests and diseases, spray when necessary.

However, be sure to obtain the incidence and severity ratings before applying any

pesticide.

Hilling-up and Weeding. Hill-up and off-bar 3-4 weeks after planting. Weed

within the row whenever necessary.

Harvesting. Exclude two end hills per row. Hence the effective harvestable area

is only 10.8 sq. m. containing 18 hills per row. Record the actual number of hills

harvested per row. Results from an entry with more than 1 missing plot must be excluded

in the analysis. Harvest the individual hill using a spanding fork. Record the yield per

area basis.

Seasonal harvesting is as follows:

Low elevation sites:

Dry season - 105 days after planting

Wet season - 120 days after planting

High elevation sites:

Dry season - 120 days after planting

Wet season - 150 days after planting


1. Field Stand – Record the number of plants for each entry at harvest.

2. Dry Matter Content – Determine for selected stations only (refer to page ____ ).

3. Starch Content – Determine for selected stations only (refer to page _____ ).

4. Pest and Disease Rating – Indicate the pests or disease rated. Use the 1 to 9

scale (refer to pages ____ & ____ ).

15

5. Shape of Storage Roots – Use the IPGRI identification system (Fig. 8).

6. Sensory Evaluation – Do this for table types only.

7. Marketable Yield – Consider only roots with diameter of at least 2.5 cm.

a. Number – Count the storage roots and record.

b. Weight – Weigh all storage roots and record. Express weight in kilogram.

8. Non-marketable Yield – Consider roots with a diameter of less than 2.5 cm.

9. Total Yield – Add the figures from 7 and 8 to get total number and weight of

roots.

10. Remarks – Record any other pertinent observation such as climatic and soil data.

Yield Calculation:

Plots with more than 30% missing hills will be excluded in the analysis.

The formula in converting yield from kg/plot to tons/ha is:

Yield (tons/ha) = Yield (kg/plot) x 0.92592

Figure 6. Field layout for one replication of a 16-entry sweetpotato trial

5.7 m

5.7 m

Sub-block I

(8 plots)

Sub-block II

(8 plots)

16

Figure 7. Suggested field layout for a 16-entry sweetpotato trial with 4 replications.

BR BR

Sub-block I, Rep. 1

BR BR

Sub-block I, Rep. 1

Sub-block I, Rep. 3

Sub-block I, Rep. 3

Border Rows (BR)

BR BR

Sub-block I, Rep. 2

Sub-block I, Rep. 4

BR BR

Sub-block I, Rep. 2

Sub-block I, Rep. 4

Border Rows (BR)

17

Figure 8. How a plot should look. In harvesting, exclude two end-hills per row.

(Effective harvestable area will be 10.8 sq. m.)

5.7 m

2 m

* *

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

* *

SUB-BLOCK OF

REPLICATION

1m

1m

18

Types of storage root shape

round elliptic round elliptic

ovate oblong obovate

long oblong long irregular

or curved

long elliptic

19

NRCCTP Form No. 3

NATIONAL ROOT CROP COOPERATIVE TESTING PROGRAM

SWEETPOTATO REGIONAL TRIAL

LOCATION: ________________________________ PLANTING DATE: _____________

SEASON: ________________________________ HARVEST DATE: _____________

Plot

No.

Entry

Name

No. of

Olants Harvested

Dry

Matter Content

Maturity Survival

Rate

Shape

of Roots

Skin

Color

Flesh

Color

Texture Eating

Quality

Pest & Diseases Weight & Number Remarks

Weevil Scab Marketable Non-

Marketable

Total

%

infestation

No. Wt. No. Wt. No. Wt.

20

PROCEDURE FOR GABI EVALUATION TRIALS

General Procedure

Choice of Land. Select an area which is well drained and more or less uniform in

fertility and slope. Ideally, use an area for one gabi cropping only. However, if land is

limited, at most two cropping evaluations may be done in the same area for as long as the

area will be fallowed for 2-3 months. An area previously used for other trials can only be

used for varietal evaluation if the previous trial imposed uniform cultural management.

Soil fertility variation must be controlled to the minimum.

Land Preparation. Plow the area twice when using a carabao-drawn implement.


harrowing maybe sufficient when tractor-drawn plow and harrow are used.


four replications.

Size of Plot. An entry will occupy a four row plot, 4 m x 3 m, with 0.75 m

distance between rows and 0.50 m spacing between hills.

Field Layout. Make each replication or block as square possible. Examples of

field layouts using sixteen (16) and eight (8) entries are shown in Figures 10 and 11.

Planting Materials. For planting materials, use suckers but remove the lower

portion of the corm or cormel. Remove all the leaves; leave only 3-4 petioles per sett

(part of the stem and upper portion of the corm). Use planting materials of the same size

per replication.

New entries for evaluation will be provided by the breeder and shall be

propagated in the different stations at least 6 months before the start of the new set of

trials.

Planting Method. Furrow planting is required. Follow the spacing of 75 cm

between furrows and 50 cm between pplants in the furrow. Bury or insert the planting

materials within the furrow up to a depth of 10 cm, then cover with soil.

Fertilizer Application. Have the soil in each site analyzed. Adjust the rate of

fertilizer to be applied based on the recommended rate of 30-30-30 kg N, P2O5, K2O. At

planting, apply half of the whole amount basally on a per hill basis. Apply the other half

at 2 months after planting.

Irrigation. Irrigate as often as necessary.

21

Pest Control. Apply pesticide when necessary. Rate the incidence and severity of

the pest before pesticide application.

Hilling-up and Weeding. Weed within the first 2 months after planting and later

whenever necessary.

Harvesting. At 8 months after planting, harvest all plants in each plot for yield

estimation. Record the actual number of hills harvested per plot. Exclude plots with more

than 30% missing hills and entries with more than one missing plot in the analysis.


1. Field Stand – Record the number of plants harvested for each entry.

2. Dry Matter Content – Analyze in all stations by replications.

3. Starch Content – Determine in selected stations only.

4. Pest Rating – Use the 1 to 9 scale. (refer to p. ____ )

5. Disease Rating – Use the 1 to 9 scale. (refer to p. ____ )

6. Sensory Evaluation – Follow the standard procedure discussed in p. ____

7. Yield – Adjust main corm yield to tons per hectare using the formula below:

Yield (tons/ha) = Plot Yield (kg) x 0.8333

8. Remarks – Specify other observations obtained.

22

Figure 10. Suggested field layout for a 16-entry gabi trial with four replications.

BR BR

Sub-block I, Rep. 1

BR BR

Sub-block II, Rep. 1


Sub-block I, Rep. 3

TWO ROWS OF GUARD PLANTS (TRGP)

BR BR

Sub-block I, Rep. 2

Sub-block I, Rep. 4

BR BR


Sub-block II, Rep.

TWO ROWS OF GUARD PLANTS (TRGP)

23

Figure 11A. Suggested field layout for an 8-entry gabi trial with four replications.

B. Sample of a whole plot which is also the effective harvestable area

4 m 4 m

P1

P3

P5

P7

P2

P4

P6

P8

Rep II

Rep III Rep IV

8 m

3 m

3 m

12 m

A

* * * * * * *

*

* * * * * * *

*

* * * * * * *

*

* * * * * * *

*

B

.5m

.75m

24

PROCEDURE FOR UBI AND TUGUI EVALUATION TRIALS

General Procedure:

Choice of Land. Select an area which is well drained and more or les uniform in

fertility and slope. Ideally, use an area for one ubi/tugui cropping only. However, if land

is limited, at most cropping evaluations may be done in the same area. An area previously

used for other trials can only be used for varietal evaluation if the previous trials imposed

uniform cultural management. Soil fertility variation must be controlled to the minimum.



harrowing maybe sufficient when tractor-drawn plow and harrow are used. After the last

harrowing, construct ridges 1.0 m apart.

Experimental Design. Use a randomized complete block design (RCBD) with

four replications.

Size of Plot. The entries should occupy 4-row plots measuring, 6 m x 4 m each, 1

meter between rows and 75 cm between hills replicated four times.

Field Layout. Make each replication as square as possible.

Preparation of planting materials. Use setts (portion of the tuber) as planting

materials. Prepare 200 gram setts for ubi and 100 gm for tugui. Treat them with wood ash

or fungicides after licing.

Planting. Plant the setts at a distance of 1 m between rows and 75 cm beween

hills, and at a depth of 10 cm from the top of the ridge.

Replanting. Plant all extra setts at the same time to enure germination. Use the

pregerminated setts to replace the missing hills. Replanting should be done 2 weeks after

planting.

Fertilizer Application. At planting, apply fertilizer basally at a rate of 30-30-30

kg NPK per hectare.

Weeding. Weed whenever necessary.

Staking. When plants start to emerge, place one stake per hill. The stakes should

extend 2 m above the ground.

Spraying. Spray the plants with fungicides (e.g. Benlate, Zineb) or insecticides as

the need arises.

25

Hilling-up. Hill-up ar 2 months after planting. When storage roots get exposed,

hill-up using shovels from time to time.

Harvesting. Harvest during or after senescence. Record the actual number of hills

harvested per plot. Exclude plots with more than 30% mising hills in the data analysis.

Harvest all rows for yield estimates.


1. Percentage Germination – Observe this at one month after planting

2. Pests and Time of Occurrence – Determine these at 3, 4 and 5 months after

planting (MAP)

3. Date of Maturity (weeks) – This refers to the time from planting th senescence

4. Tuber Acceptibility

a. Appearance

b. Aroma

c. Taste

d. Texture

e. General Acceptability

5. Yield per Plot

a. Marketable – Determine weight and number of tubers which are at least 300

gm for ubi and 100 gm for tugui

b. Non-marketable – Determine weight and number of all other tubers

6. Dry Matter Content of Tubers – Analyze actul dry matter content for all stations

7. Remarks – Record other pertinent observations and other climatic data

26

Figure 12. Siggested field layout for a 16-entry ubi and tugui trial with four

replications.

BR BR

Sub-block I, Rep. 1

BR BR



Sub-block I, Rep. 3

Border Rows (BR)

BR BR

Sub-block I, Rep. 2

Sub-block I, Rep. 4

BR BR



Border Rows (BR)

27

Figure 13A. Suggested field layout for an 8-entry ubi and tugui trial with four

replications

B. Sample of a whole plot which is also the effective harvestable area

6 m 6 m

P1

P3

P5

P7

P2

P4

P6

P8

Rep II

Rep III Rep IV

12 m

4 m

4 m

16 m

A

* * * * * * *

*

* * * * * * *

*

* * * * * * *

*

* * * * * * *

*

B

.75m

1.0m

28

NRCCTP Form No. 4

NATINAL ROOT CROP COOPERATIVE TESTING PROGRAM

UBI AND TUGUI REGIONAL TRIAL

LOCATION: _________________________________ PLANTING DATE: ___________________

SEASON: _________________________________ HARVEST DATE: ___________________

Plot

No.

Rep.

No.

Entry

Name

No. of

Plants

Maturity Number of Tubers Weight of Tubers (kg) Tuber

Dry

Matter

Content

Disease Rating Remarks

Marketable Non-

Marketable

Marketable Non-

Marketable

Anthracnose Leaf

Rust

ETC

29

STANDARD PROCEDURE FOR POTATO EVALUATION TRIALS

General Procedure

Choice of Area. Select an area which is relatively free from bacterial wilt (BW),

with good drainage and uniform soil fertility. Ideally, andy loam loam to clay loam soils

with pH ranging from 5.6 to 6.5 and high organic matter content are preferred. The trials

shall be conducted for at least four (4) seasons (2 dry, 2 wet) in at least two sites per

elevation. In the lowlands however, the trials shall be conducted for two crop seasons

only in at least two sites.

If possible, collect soil samples for laboratory analysis of bacterial wilt and

nematode diseases before setting-up the trial.

Land Preparation. Prepare the land thorough by plowing and harrowing at the

right soil moisture. Do each operation at least twice.

Experimental Dasign. Use the randomized complete block design (RCBD) with

three to four replications depending on the available area and planting materials. Plant at

least 40 to 60 plants per plot (or 20 to 30 plants per row) for each entry. Plant one border

row on each side of the experimental area and at least two hills of border plants at both

ends of each plot.

Size of Plot. Each plot must have two rows (double row) measuring 6.6 m long.

Space the two furrows 40 cm apart in the double row. Double rows must be 90 cm apart.

See Figs. 13-14 for illustration.

Planting Distance. Space the plants at 30 cm between hills in each row.

Field Layout. Make each replication/block as square as possible. An example of

blocking for 10 entry trials is shown in Fig. 14.

Border Rows of the Experimental Area. Provide a double row around the

whole area, at least three border hills on each end of the area, and 50 cm space with a

length of 5 m between double rows.

Planting Materials. Select good seed tubers for planting, i.e. full in form and of

the right physiological age. The recommended seed tuber size is 30 to 50 mm in diameter

or 40 to 60 gm in weight with 2 to 4 sturdy green sprouts, measuring about 0.5 to 1.5 cm.

Make sure that that the seed tubers are free from insect pests and diseases

especially bacterial wilt (BW) and viruses. Never use cut tubers unless very necessary

and when there is no problem on soil-borne diseases in the area. keep the source, size and

age of the planting materials as uniform as possible. Classify seeds into large, medium

and small. Plant only seeds of similar size in each replication.

30

Include at least two highland recommend cultivars as local check. As much as

possible, seed tubers of these check cultivars should come from the same source as the

test entries. Use a maximum of 10 entries for each trial.

Pre-planting Treatments. Pre-planting treatment foreasy germination maybe

done whenever necessary.

Planting Method. Plant on ridges and follow the double-row method of planting.

Space the two furrows in the double row at 40 cm. Provide a space of 50 cm between

pairs of furrows or between double rows and 30 cm between hills within furrows. Plant

parallel within the double rows of the experimental unit. Provide a pathway of 1 meter

between replications.

Fertilization. If possible, fertilizer application should be based on soil analysis.

The usual recommendation is 140-140-140 NPK fertilizer is recommended. Chicken

manure (or any available organic matter) at 2 tons/ha must be incorporated into the soil

during land preparation. In the absence of soil analysis, additional nitrogen fertilizer (50

kg N/ha) may be sidedressed 25 to 30 days after planting or before hilling-up.

Irrigation. Water the plants as often as necessary. The first 4 to 5 weeks is the

most critical period, hence supply sufficient water at this time. If possible, do not employ

flood irrigation to minimize the possible spread of BW. If there is no rain, irrigate at 5 to

7 dys interval. Stop watering 15 days before harvest.

Pest Control. Spray pesticides as the need arises. Control weeds especially

during the first 4 to 6 weks of the growing period.

Hilling-up. Hill-up once at 25 to 30 days after planting or during the sidedresing

of the additional nitrogen fertilizer.

Harvesting. Before digging, record the number of hills to be harvested per plot.

Exclude the two ebd-hill per row, leaving 20 inner hillsto be harvesyed; effective

harvestable area is 7.8 sq. m. Exclude plots with more than 30% missing hills.

Grade harvested tubers according to size, following he size description in number

7 under data to be gathered.

For mid-highland evaluation, harvest at 90 to 150 days after planting. For lowland

evaluation, harvest 70 to 80 days after planting.

Storage of tubers. Store the seed tubers under diffused light condition to evaluate

dormancy and storability. Before storing, treat the tubers properly (they could be used in

subsequent trials) by dipping or dusting them with an insecticide-fungicide mix. Record

all data on dormancy, tuber number ad weight losses. At the end of the storage period (8

31

to 9 months after harvest), rate the tubers in terms of degree of shrivelling and sprouting.

Follow the rating scale of 1-5 for each parameter.


1. Number of hills planted, plant emergence (number) at 30 DAP and number of

hills harvested

2. Days of Emergence – Observe this when 50% of the total plants/plot have

emerged

3. Plant Vigor – Record this at 30 to 45 days after emergence using the 1 to 5 rating

scale (1-highly vigorous, 3=medium, 5=very poor vigor)

4. Maturity/Senescence Rating – Determine this at 70 and 80 DAP before

dehaulming using the 1 to 5 rating scale. (1 – very early or no senescence; 5 –

very late or fully senesced)

5. Insect Rating – Do separate ratings for viruses, aphids and other specific major

insect pests. Use the rating scale of 1 to 9 in increasing order of severity.

6. Disease Rating – Do separate ratings for BW, late blight, scab or other specific

major diseases. Use the rating scale of 1 to 9 in increasing order of severity. For

BW, conduct a water test to verify and count the number of wilted plants. All

plants with BW must be rogued.

7. Yield and its Components – Separate marketable and non-marketable tubers. Get

their total weight and number.

Yield Calculation:

Get yield on per hill basis but later compute yield in tons/ha or per area

basis (approx. 50,000 plants/ha).

Convert yield per plot to per hectare basis as follows:

Yield (tons/ha) = Yield (kg)/plots x 1.28205

Classify tubers according to size as follows:

Size Grams

Extra Large More than 100 g

Large 80 to 99 g

Medium 50 to 79 g

Small 30 to 49 g

Marble-ize Less than 30 g

32

8. Analyze the tubers according to the solid (dry matter) and sugar contents.

Unmarkable tubers are those weighing less than 30 g. Record the

percentage of cracking and secondary growth for each size. Also record/rate the

occurance of tuber diseases.

Farmer’s Preference Rating

1. Encourage the farmer-partner and other farmers (at least 5 to 10 farmers) to

follow-up/ visit the trial regularly. Conduct farmer’s preference rating at:

a. 50 to 5 DAP using 1 to 5 rating scale 1 – highly preferred; 5 – not preferred).

b. at harvest using the same rating scale above for yield, tuber size and

appearance

Tuber Quality Evaluation

1. Evaluate processing quality for chips and fries. Private processing companies may

be invited to evaluate the clones for processing (chips).

2. Form a taste panel for boiled potato tubers.

33

Field Layout for Potato

Figure 14. Field layout for a single replication of potato evaluation trial showing

dimensions of double rows and plot.

Plot size – 6.6 x 1.3 m

Distance between double rows – 90 cm

Effective plot area – 0.195 sq. m.

Effective harvestable area – 7.8 sq. m.

No. of plants harvested/row – 20 inner plants

Border rows

25 cm 40 cm 40 cm

Border rows

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6.6 m 6.6 m

6 m

1.3 m

34

Figure 15. A detailed illustration of potato trial on a plot basis

Plot size – 6.6 x 1.3 m

Distance between double rows – 90 cm

Effective plot area – 0.195 sq. m.

Effective harvestable area – 7.8 sq. m.

No. of plants harvested/row – 20 inner plants

40 cm

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40 cm 25cm 25cm

40 cm

60 cm

60 cm 40 cm

35

NRCCTP Form No. 5

NATIONAL ROOT CROP COOPERATING PROGRAM

POTATO REGIONAL TRIAL

LOCATION: _______________________________ PLANTING DATE:

___________________

SEASON: _______________________________ HARVEST DATE:

___________________

Plot

No.

Rep.

No.

Entry

Name

No. of

Plants

Maturity Insect Pest Disease Rating Weight of Tubers (kg) Tuber

Dry

Remarks

Aphids Thrips Late

Blight

Bacterial

Wilt

Viruses Etc. Marketable Non-

Marketable

Matter

Content

36

PROCEDURE FOR RATING OF THE DIFFERENT

ROOT CROPS ARTHROPOD PESTS

Cassava

Rating for insect pest infestation must be done at monthly intervals from the third

month after planting until harvest.

Rating of cassava spider mite, scale insect and whiteflies infestation should start 3

months after planting and should be done monthly until harvest especially during the dry

season. During the wet season, rating maybe done only during the months when high

infestation occurs. Damage rating will be done on 10 randomly selected plants in the

inner rows per replicate. To determine percent infestation, consider all infested plants in

the inner rows over the total number of plants/hill in all inner rows.

Red spider mite

Tetranychus kansawai Kishida

Level of Damage Type of Damage and Level of Infestation

0 Plant without mites; no damage

2 Basal or mid-leaves with some light ellow speckles;

about 10-20 specks grouped or dispersed over each leaf

3 Basal or mid-leaves with definite or noticeable yellow

speckles, about 50-100 spots per leaf

5 Extensive damage on basal and middle leaves of plants;

leaves completely speckled; yellowing and necrosis of

basal leaves; webbing on some leaves

7 Plants with general yellow appearance; mites on all

leaves; basal and middle leaves mostly affetced;

webbing on some leaves

9 Plants severely defoliated; mites abundant on all parts

of the plants; leaf necrosis; plants may die

37

White peach scale

Psuedaulascaspis pentagona Targiona-Tozzetti

Level Damage Type of Damage and Level of Infestation

0 No scale prsent

1 Few scales found around lateral or terminal buds

3 Same as in 2; some internodes attacked

5 Scales completely covering growing points and 50% of

internodes; loss of lower leaves

7 Approximately 75% of stem and branches covered with

scales; loss of intermediate leaves

9 Scales completely covering stem and branches;

desiccation of terminal shoots

Mealybug

Ferrisiana virgata Cockerel

Phenococcus hirsitus Green

Pseudococcus elisae Borchsenius

Include rating of mealybug infestation of roots at harvest. Rate at monthly

intervals during both dry and wet seasons.


0 No nymphal stages or adults present

1 Nymphs found on underside of lower leaves

3 Same as in 1; chlorotic pots begin to appear on these

leaves

5 Adults, nymphs and ovisacs present; partial chlorosis of

basal leaves

7 Adults, nymphs and ovisacs on petioles and or stems;

total chlorosis of lower leaves and/or necrosis of their

margins; sooty mold on petioles and leaves

9 Death of growing points and new lateral buds attacked;

leaf necrosis and leaves fall; desiccation of stem

38

Whiteflies

Bemisia tabaci Gennadius

Aleurodicus disperus Russel


0 No infestation by adults/ no pupa on laf

1 Less than 20% infestation of leaves/ less than 5 pupae

per leaf

3 20-40% infestation of leaves/ 5-10 pipae per leaf

5 41-60% infstation of leaves/ 11-50 pupae per leaf

7 61-80% infestation of leaves/ 26-50 pupae per leaf

9 81-100% infestation of leaves/ more than 50 pupae per

leaf

39

NRCCTP Form No. 6

NATIONAL ROOT CROPS COOPERATIVE TESTING PROGRAM

EVALUATION FOR RESISTANCE TO CASSAVA PESTS

Entry

Spider Mite

Date of

Observation ___________________

Scale Insect

Date of

Obervation ____________________

Whiteflies

Date of

Observation _________________

%

Infestation

Damage

Rating

Reaction %

Infestation

Damage

Rating

Reaction %

Infestation

Damage

Rating

Reaction

40

Sweetpotato

Rating of other pests (e.g. grubs be included using a rating scale of 0-9.

For other pests/diseases encountered but not included in the manual, contact

PRCRTC for assistance and assesment. Illustrations/pictures should accompany the

disease description, rating and scale.

1. Sweetpotato Weevil

Cylas formicarius Fabr.

Rate sweetpotato weevil infestation at harvest. The criteria used in

evaluating resistance will be based on percent weevil infestation, surface area

damaged and number of tunnels.

To determine percent weevil infestation, consider all roots from all inner

rows per replication. For damage rating, take 15-20 infested roots from

replication of the three replications. Use the following rating scale.

Rating Scale for Sweetpotato weevil (Cylas formicarius Fabr.) Infestation

Rating Description

External Damage

1 1 to 10% of surface area damaged

3

11 to 20% of surface area damaged

5

21 ro 40% of surface area damaged

7

41 to 60% of surface area damaged

9

61% or more of surface area damaged

Internal Damage

1 No damage; No tunnels or weevil in root

3 1-2 tunnels or weevil per root

5 3-4 tunnels or weevil per root

7 5-6 tunnels pr weevil per root

9 7 or more tunnels or weevil per root

41

NRCCTP Form No. 7

NATIONAL ROOTCROP COOPERATIVE TESTING PROGRAM

EVALUATION FOR RESISTANCE TO SWEETPOTATO WEEVIL

Entry W E E V I L (Date of Observation)

% Infestation Damage Rating

(External & Internal)

Reaction

42

Taro

Rate taro spider mite, scale insect and whiteflies infestation monthly from 3

months after planting until harvest especially during the dry season. During the wet

season, rating may be done only during the months where high infestation occurs.

Damage rating will be done on 10 randomly selected plants in the inner rows per

replicate. To determine percent infestation, consider all infested plants in the inner rows

over the total number of plants/hill in all inner rows.

RATING SCALE FOR TARO ARTHROPOD PESTS

Hornworm (Hippotion celerio Linn.)

Grasshopper (Gesonula mundata zonocera Navas)

Cutworm (Spodoptera litura Fabr.)

Level of Damage Description

0 No damage

1 1 - 5% leaf area damage/defoliation




9 76 - 100% leaf area damage/defoliation; unopened leaves

and petioles attacked

43

Aphid (Aphis gossypii Glover)


0 No aphids

1 Few adults and nymphs on nether surface of leaves

3 Several colonies on nether surface of leaves

5 Many distinct colonies on nether surface of leaves

7 Many distinct colonies on nether surface of leaves and

petioles

9 Many distinct colonies on nether surface of all opened

leaces, unoppened leaves and petioles

Taro green mite (Schizotetranychus lechrius Rimando)


0 No mites or no damage

1 Few mites; initiation of silvery spots on some basal and/or

middle leaves

3 Many mites on some leaves; fairly abundant silvery spots

on basal and middle leaves; extensive damage

5 Many mites on some leaves; abundant silvery spots on

basal and middle leaves; fairly extensive damage

7 Many mites on all open leves; entire and intermediate

leaves appear silvery; moderate/severe damage

9 Many mites on all open and unopened leaves; all leaves

appear silvery; browning and cupping of leaves; plants

wilt; very severe damage

44

Whiteflies (Aleurodicus dispersus Russell)


0 No infestation by adults/no pupa present

1 Less than 20% infestation of leaves/ less than 5 pupae per

leaf

3 20 – 40% infestation of leaves/ 5-10 pupae per leaf



9 81 – 100% infestation of leaves/ more than 50 pupae per

leaf

Mealybugs (Phenococcus gossypii)


0 No nympal stage or adults present

1 Nymphs found on underside of lower basal leaves

3 Same as in 1; chlorotic spots begin to appear on these

leaves

5 Adults, nymphs and ovisac present; partial chlorosis of

basal leaves

7 Adults, nymphs and ovisac on leaves and petioles;

chlorosis of lower leaves and/or necrosis of their margins;

sooty molds on leaves and petioles

9 Death of growing points and new lateral buds attacked;

leaf necrosis; wilting of leaves and desiccation of petioles

45

NRCCTP Form No. 8

NATIONAL ROOTCROP COOPERATIVE TESTING PROGRAM

EVALUATION FOR RESISTANCE TO CASSAVA PESTS

Entry

Hornworm

Date of

Observation

Grasshopper

Date of

Observation

Aphids

Date of

Observation % Infes-

ation

Damage

Rating

Reaction % Infes-

ation

Damage

Rating

Reaction % Infes-

ation

Damage

Rating

Reaction

46

Potato

Aphids (Aphis gossypii Glover)

(Myzus persicae Sultzer)


0 No aphids

1 Few adults and nymphs on nether surface of leaves

3 Several colonies on nether surface of leaves

5 Many distinct colonies on nether surface of leaves

7 Many distinct colonies on nether surface of leaves and

petioles

9 Many distinct colonies on nether surface of all opened

leaves, unopened leaves and petioles

Thrips (Thrips palmi)

(Thrips tabaci)


0 No infestation by aults / no pupa on leaf

1 Less than 20% infestation of leaves / less than 5 pupae per

leaf

3 20 – 40% infestation of leaves / 5 – 10 pupae per leaf



9 81 – 100% infestation of leaves / more than 50 pupae per

leaf

47

PROCEDURE FOR RATING OF THE DIFFERENT ROOTCROP DISEASES

Cassava

Cassava Bacterial Blight (CBB) Xanthomonas manihotis

Scale Decription Reaction

1 No symptom Highly Resistant

(HR)

3 Angular spot 15%;

defoliation not more than 30%

Resistant

(R)

5 Angular spot and blighting;

more than 50% defoliation;

more than 30% with gum

exudation

on stem

Moderately Resistant

(MR)

7 Total defoliation; death of the

lower lignified portion of stem

Susceptible

(S)

9 Total death of plant Highly Susceptible

(HS)

*Frequency of rating – bimonthly

*Sample size – 10 plants/replication/entry

48

Leaf spot (Cercospora vicosae and Cercosporidium henningsii)


1 0-20% of leaves are affected (foliar lession)

defoliation

HR


defoliation

R


defoliation

MR


defoliation

S


defoliation

HS

*Frequency of Rating – Bimothly

*Sample Size – 10 plants/replication/entry

Sweetpotato Stem and Foliage Scab

Disease rating of sweetpotato scab coulb be done either in the field or in the

screenhouse. When done in the field, gather the estimated of infections from 10 randomly

selected plants per variety per replication. For screenhouse evaluations 2 – 5 plants per

variety may be used.

For disease evaluation in the field, use 2 rows with 12 plants per row per

replication. The best sample size is 10 plants per entry. When artificial infection is done,

the initial rating should be done 7 – 14 days after inoculation and the final rating at one

month before harvest. In case of natural infection, the initial rating should be done 28 –

30 days after planting and at 28 – 30 days before harvest for the final rating.

49

Sweetpotato Scab

Screenhouse Experiment


1 No symptom on leaf and stem HR

3 Occasional lesions on their the stem

or leaf, 10 lesions per 30 cm vine

R

5 Scattered lesions on stem and leaves;

10 – 20 lesions per 30 cm of vine

MR

7 More than 20 lesions per 30 cm of vine;

slight leaf deformation

S

9 Numerous lesions on both leaf and stem

with severe leaf deformation

HS

50

Sweetpotato Scab

Field Experiment


1 No symptoms HR

3 Occasional lesions on leaf ans stem but

no leaf deformation

R

5 Slight deformation of leaves and petioles MR

7 Moderate leaf deformation accompanied by

cupping

S

9 Severe leaf deformation and cupping HS

Sample size = 10 plants/replication/entry (2 rows with 12 plants/row)

Frequency of Rating

Induced Infection: 7 – 14 days after inoculation (initial rating)

1 month before harvest (final rating)

Natural Infection: 1 month after planting (initial planting)

1 month before harvest (final rating)

51

Leaf Spots, Rust and Blight Diseases

Crops: Yam and Gabi

Scale Percent of Leaf Area Affected Reaction

1 Less than 1% HR

3 1 – 5% R

5 6 – 25% MR

7 26 – 50% S

9 Greater than 50% HS

*Sample size: 10 plants/replication/entry

*Frequency of Rating – 1 month after planting

1 month before planting

52

Potato

Bacterial Wilt (Psendomonas solanacearum)

Scale Description Reaction

1 One leaflet (or leaf) wilting HR

3 25% of plant wilting R

5 50% of plant wilting MR

7 Whole plant wilting S

9 All plant dead HS

Leaf blight (Phytophthora infestans)

Scale Percent of Leaf Area Affected Reaction

1 Lesions none or very few HR

3 2% but not more than 25%

infection

R

5 25% but not more than 50% of the

foliage destroyed

MR

7 50% but not more than 75% of the

foliage destroyed

S

9 75-100% or foliage completely

destroyed

HS

53

STANDARD METHOD OF PREPARING ROOTCROPS

SAMPLE FOR DRY MATTER AND STARCH DETERMINATION

The method of sample preparation which enormously affects the final result in an

analytical procedure but its importance is often overlooked. Plant materials should be

sampled immediately to avoid breakdown of the chemical constituents and to minimize

the effects of temperature, light and air. Sampling should be carried out very carefully

because analysis is useless if the results ontained do not adequately represent the

composition of the whole material from which the sample was drawn.

Sample preparation includes sampling, cleaning to avoid contamination, size

reduction, stabilization and storage. The greatest error usually arises during sampling and

errors associated with sample analysis itself.

Size reduction is done by chopping and/or blending. Obviously, this process

should be carefully carried out so as to avoid the introduction of foreign materials into the

sample. Once broken down, the materials should be ove-dried to maintain the chemical

composition and to arrest biochemical reactions.

A. Sample Preparation for Chemical Analysis

Procedure:

1. Take three to five samples of small, medium and large tubers/roots/corms.

2. Wash to remove soil and adhering debris

3. Peel and remove any disease-infected part

4. Use whole tuber/root as sample if it is small. If the root/tuber is larger (for

sweetpotato, yam and taro), take two quarters then bulk them together. For

cassava roots, take three slices of about 50-100 g each (one from each end and

one slice from the middle) then bulk them together.

5. Cut the samples into 1 cm cubes and chop them using a blender.

54

6. Take a representative sample after mixing well the material. Dry samples in a

convection oven at 40-50ºC until constant weights are obtained or in a forced-

draft oven at 45ºC for 36 to 48 hours.

7. Grind dried samples finely using a Wiley mill and store in air-tight bottles.

This sample will be used in the analysis of starch, protein and other

constituents.

B. Sample Preparation for Moisture Analysis

Procedure:

1. Follow steps 1 – 5 of sample preparation for chemical analysis

2. Weigh about 15 – 20 g of the well mixed, freshly sliced sample and place in

aluminum foil boxes. Prepare two samples.

3. Dry the samples at 100ºC until constant dry weights are obtained (usually for

5 –6 hours), or in a forced-draft oven for 36 to 48 hours.

4. Take samples from the oven then cool the dired samples in a dessicator

5. Take the weight of the dried samples

6. Calculate % moisture using the formula:

%moisture = (fresh wt. – dry wt) / fresh wt. x 100

55

RAPID EVALUATION OF CYANIDE CONTENT OF CASSAVA ROOTS

Procedure:

1. Cut 1 x 6 cm strips of Whatman no. 1 filter paper.

2. Prepare alkaline picrate stock solution by dissolving 25 g anhydrous sodium

carbonate and 5 g moist picric acid in a liter of distilled water. This is

essentially a saturated solution and may be stored for several months..

3. Dil filter paper strips into picrate stock solution and drain free from excess

liquid just before use.

4. Place 1 g sample of cassava root in a test tube.

5. Add 5 drops of toluene.

6. Immediately suspend the filter paper strip saturated with alkaline picrate

above the sample and hold it in place with a cork or rubber stopper.

7. leave at room temperature for 24 hours.

8. Rate using 1 – 5 or 1 – 9 scale based on intensity of red color. (higher

intensity of red = higher HCN content of root sample.

56

TECHNIQUES IN SENSORY EVALUATION

Importance

The acceptability of a food product is ultimately judged by the consumers based

on its sensory properties. Sensory evaluation therefore is an important part of crop

evaluation and product development. Care must be observed to minimize errors

especially since sensory responses are greatly affected by many factors such as type of

individual acting as sensory evaluation methods to make them aware/updated of the

importance, procedure and technique used and to increase the reliability of sensory

evaluation results.

Aims of Sensory Evaluation

1. To evaluate the sensory characteristics of the different NCT entries

2. To determine the acceptability/preference of the different NCT entries

DO’s and DON’T’s in Sensory Evaluation

DO’s

1. Allow the panelists to rest before the test.

2. Wash hands with soap before the test.

3. Concentrate while doing the test.

4. Rinse your mouth between samples.

5. Ask help from person in-charge of the sensory evaluations.

6. Place each panelist in separate compartment or booth.

7. Make the size and shape of the sample uniform.

8. Control the number of samples per panelist.

9. Each panelist should evaluate one set of samples per session.

10. Employ at least 24 people per session/replication in an individual booth.

57

DON’T’s

1. Do not allow pregnant or lactating women to join sensory evaluation.

2. Do not do the following 30 minutes to 1 hour before the test.

take snacks

drink anything with lingering after taste

use strong smelling cosmetics

eat sucking candies and chewing gums

eat highly spiced foods

3. Do not make unnecessary noise during the test.

4. Do not converse with your neighbors during the test.

5. Do not let the panelist see the other sets of samples.

6. Do not let a panelist who has not slept to participate in the sensory evaluation

Procedure

A. Prepare a Master Sheet

1. Write all the necessary information about the test on the master sheet such as

name of the product, testing date, replication number, type of test, judges

random code, assignment of sample and order of serving (Appendix Form

Nos. 1 and 2).

2. Assign the random code number of each sample for each judge or set. Use 3-

digit random numbers which can be taken from the Table of Random

Numbers (Appendix Table 1). Skip double numbers such as 122, 333, 499 or

those with number 13 like 213, 313 or 413.

3. Carefully examine the code number of each sample for each judge so that no

two samples of the same code numbers appear for each judge.

4. Determine random order of presentation of samples for each judge employing

the Table of Random Numbers-Permutations of Nine (Appendix Table 2).

Make sure that this differs from one judge to the other so than each sample

has equal chances of being eaten first, mid or last. Write the order of serving

of the samples on the upper right hand corner of the 3-digit random code

number of the samples.

58

B. Prepare Score Sheet

1. Prepare a score sheet for each judge (Appendix Form No. 3). Fill up the

necessary information such as judge number, date of testing and code number

for each judge.

2. Copy the random code number assignment of the samples following sequence

of random order of presentation from the master sheet.

3. Accomplish all score sheets for each judge or set if the test calls for several.

C. Prepare Code Numbers and Containers

1. Mark the sample containers with the 3-digit random numbers copied from the

master sheet. Use a marking pen which does not impart odor to containers and

samples. The same ink color should be used in all samples for each judge and

among judges.

D. Prepare Samples

1. Cut samples into uniform sizes and shapes about 20 g each and place into

designated containers. If liquid, place aliquot samples about 15 – 20 ml into

the designated containers.

E. Set-up trays and serve

1. Arrange samples on the tray/plate according to random order of serving. Make

sure that this order tallies with the score and master sheets.

2. Place score sheet on each tray/plate.

3. Serve. Provide a glass of water for each tray/plate and advise the panelists to

thoroughly rinse their mouth with water before tasting the next sample.

F. Decode Score Sheets

With the master sheet as guide, convert back the code number into treatment or

sample number (Appendix Form No. 4).

G. Compute the date using ANOVA and DMRT.

59

IMPORTANCE OF UNIFORM FIELD PILOT TECHNIQUES

IN THE CONDUCT OF VARIETY TRIALS

In any crop variety trial, uniform methodology and strict adherence to the

principles of designing an experiment are necessary. Residual variation or experimental

error (as reflected by the coefficient of variation) must be minimized in each trial per

cropping season per location. The specific procedure for each crop is described in this

manual for easy implementation. This section aims to emphasize to project/study leaders

of the NRCCTP, (both old and new ones) the value of a carefully conducted research.

Experimental Error

In statistics, experimental error refers to the variation (differences) among

experimental units which have been treated alike. In field trials, experimental error

should only be attributed to soil heterogeneity. Common mistakes commited in the

conduct of an experiment may inflate experimental error, hence reduce the accuracy or

results. Thus, it is imperative to put extra care in conducting an experiment. The

principles of experimental design i.e., randomization, replication and local control

(“Blocking”) must be applied to minimize experimental error.

Local Control

Soil heterogeneity is a common source of variability in field experiments.

Blocking is one way to minimize variability due to soil heterogeneity. Here, the

experimental area is divided into groups or blocks with relatively homogeneous

experimental units within them (e.g. more or less uniform soil fertility). Precision of the

experiment is enhanced since each treatment (variety) is compared with all other

treatments (varieties) in the same block. The differnce among blocks is segregated from

the random variation among plots in the experimental error.

Plots within each block are assumed to be uniformed in all soil factors. This

means that correlation of yields between plots of the same block is higher than that

between plots of different blocks.

60

It is better to choose an experimental area with known soil fertility. As much as

possible, the area must be uniform in slope. In the fertility status of the area is unknown,

heterogeneity is assumed and so the trial must be carefully laid out using some qualitative

indices of soil heterogeity such as slope of the area, growth of plants (weeds) or path of

water flow.

For a variety trial, the chosen area must not have been previously used for any

fertilizer trial using various fertilizer rates. Residuals of fertilizer treatments often

markedly affect yield of a variety. Ideally, a chosen area must have been used for an

experiment with uniform cultural management such as for seed production of a single

variety.

Labelling and tagging of plots can also reduce risk of unintentional mistakes

during data gathering. Correct tags and labels using durable material are necessary.

Careless labeling may lead to wrong identification and can distort the results. Some

researchers have the erroneous notion that results can be adjusted through statistical

methods. Statistics is just a tool to detect and separate differences among treatments. Any

mistake committed in the conduct of an experiment can never be corrected by any

statisrtical technique. A mistake may result in reduced precision and inaccurate results

often lead to wrong conclusions.

Randomization

The manner of randomization depends on the chosen experimental design. All

variety trials for rootcrops must use the randomized complete block design (RCBD).

Thus, randomization of treatment (varieties) must be within each block. Randomization

should be independent for each block, i.e. random assignment of varieties in one block

must differ from those in the other blocks.

Randomization requires that each treatment assignment does not depend on the

characteristic of the materials. Every entry must have the same probability (chance) to be

assigned to any plot in a block. This ensures the independence of experimental error.

Experimental error only measures the random extraneous source of variation that cannot

be controlled by a given experimental design.

61

Replication

It has been agreed that all rootcrop variety trial must have four replicates

(repetition) of each basic experiment unit. Four replications became the choice to give

sufficient confidence level in detecting significant differences and to make allowance for

missing plots. Although increasing the number of replicates may reduce experimental

error, the management of a uniform trial may be constrained by the size. This may also

increase human error in planting, harvesting and data gathering.

Each replicate in an expriment laid out in RCBD is also the block. Blocks

preferably should be contiguously located for easy management. However, they may be

separated from each other (see Fig. 3) if the areas available can not accommodate the

whole experiment, i.e. they are small and not side by side.

Shape and Orientatrion of Blocks and Plots in a Block

There are procedures to determine the optimum plot size and shape for a variety

trial of a given crop. The procedures presently used for rootcrops trials are based on

experiments conducted at UPLB, PRCRTC and at CIAT in the case of cassava.

If the extent and direction of heterogeneity of the area to be used for a variety trial

is not known, orient or distribute plots such that a more or less square block (replication)

will result. This also means that each block have to be divided into sub-blocks. If the area

has fertility gradient and its direction is known, the blocks could be reactangular or not

sub-blocked. Blocking must be perpendicular to the direction of the heterogeneity

(gradient).

Establishment of Border Rows Around the Experimental Area

Border rows around the experimental plots are necessary not only to protect the

experiment from grazing animals but more importantly, to remove any advantage or

disadvantage of the variety planted at the edge or end of an area over those found at the

middle of the block.

62

Border Plants or Guard Rows in a Plot

To minimize the effect of interplot competition, guard or extra rows must be

provided in each plot of a variety trial. These are outer rows that will not be included

during harvesting. Such guard rows are not necessary in sweetpotato trials where

interplot competition is insignificant with the row spacing used.

Data Gathering

1. Follow the field layout in data gathering.

2. Keep a permanent record book and write the data on it. Record books in the field

must be firm and water resistant. Use pencil or indelible pen. If a mistake has been

committed cancel the mistake by a single stroke (\) and not erase it completely.

Sometimes, changes in data entries lead to unnecessary errors.

3. Measure characters and attributes necessary and relevant to the objectives based on

the defined variables set in this manual.

4. Gather covariates if necessary to ensure correct measurements. Analysis of

covariance can help to increase precision of data/results.

5. Make sure you know how to use the measurement gadgets. Ensure the precision of

your weighing scales and other measuring devices. A good knowledge of the material

used in important.

6. Always provide a copy of the field lay-out in your report, together with the data

required written on prescribed data sheets. Also, fill up the information required in

the NRCCTP Form No. 8 and send to PRCRTC, LSU, Baybay, Leyte 6521-A.

63

NRCCTP Form No. 8

National Seed Industry Council Evaluation

__________________________________________

(specify name of crop)

1. Name of Cooperator (s): _____________________________________________

2. Institute and Address: _______________________________________________

3. Location of the Trial:

Place ___________________________ Latitude ______________________

Evaluation ______________________ Longitude _____________________

4. Date of Planting: ___________________________________________________

5. Date of Harvesting: _________________________________________________

6. Soil Type (if possible): Kind of Soil ____________________________________

Result of Soil Analysis (if available) ____________________________________

7. Fertilizer Used N_______kg/ha: P________kg/ha: K_______kg/ha

8. Irrigation Method and Frequency: ______________________________________

9. Meteorological Data during the Cropping season (from planting to harvesting)

64

Appendix Form No. 1

MASTER SHEET*

Name of Product: _______________

Date: _________________________

Replication No.: ________________

Judge

No.

T R E A T M E N T S Total

*Typical master sheet used for setting up a sensory test.

65

Appendix Form No. 2*

Name of Product: Boiled Sweetpotato

Date: June 14, 1994

Replication No.: 1

T R E A T M E N T S

JUDGE

NO. 1 2 3 4 5 6

1 5934 103

2 868

6 950

2 168

3 924

5

2 1562 716

5 405

3 751

6 803

1 574

4

3 7353 259

6 783

5 345

1 832

4 769

2

4 3704 837

3 202

2 742

1 640

5 056

6

5 2675 659

4 273

6 567

2 728

1 284

3

6 5804 763

6 975

1 195

5 245

2 472

3

7 6263 631

4 745

1 107

6 153

2 138

5

8 7314 510

2 304

5 026

3 602

6 395

1

9 6592 124

6 328

3 808

1 651

4 065

5

10 5681 615

4 498

2 758

5 749

6 728

3

T1 - VSP 6 T4 - VSP 4

T2 - VSP2 T5 - RED WONDER

T3 - VSP 5 T6 - VSP 3

* A properly accomplished Master Sheet

66

Appendix Form No. 3

Boiled Sweetpotato

Name of Product

Name _____________________________ Date ___________________

Judge No. 1

Direction: Please evaluate the samples presented to you for their sweetness, texture

and general acceptability. Kindly mark x the description that best

describes the samples and rate its acceptability using the scale below.

Please rinse your mouth with tap water before tasting easch sample. Thank

you.

SWEETNESS 103 950 168 593 896 868

5 – very sweet

4 – moderately sweet

3 – sweet

2 – slightly sweet

1 – not sweet

Acceptability Score

DRYNESS/MOISTNESS

7 – very dry

6 – moderately dry

5 – slightly dry

4 – neither dry nor moist

3 – slightly moist

2 – moderately moist

1 – very moist/watery

Acceptability Score

General Acceptability

Score

Acceptability/Gen. Acceptability Score

9 – like very much 4 – dislike slightly

8 – like very much 3 – dislike moderately

7 – like moderately 2 – dislike very much

6 – like slightly 1 – dislike very much

5 – neither like mor dislike

67

Appendix Form No. 4

Boiled Sweetpotato

Name of Product

Name _____________________________ Date ___________________

Judge No. 1

Direction: Please evaluate the samples presented to you for their sweetness, texture

and general acceptability. Kindly mark x the description that best

describes the samples and rate its acceptability using the scale below.

Please rinse your mouth with tap water before tasting easch sample. Thank

you.

Sample Code

T2 T4 T3 T1 T6 T3

SWEETNESS 103 950 168 593 896 868

5 – very sweet

4 – moderately sweet x x

3 – sweet x

2 – slightly sweet x x

1 – not sweet x

Acceptability Score 8 7 8 7 6 7

DRYNESS/MOISTNESS

7 – very dry x

6 – moderately dry x x

5 – slightly dry x x

4 – neither dry nor moist x

3 – slightly moist

2 – moderately moist

1 – very moist/watery

Acceptability Score 6 8 8 7 7 7

General Acceptability

Score

7 8 8 7 6 7

Acceptability/Gen. Acceptability Score

9 – like very much 4 – dislike slightly

8 – like very much 3 – dislike moderately

7 – like moderately 2 – dislike very much

6 – like slightly 1 – dislike very much

5 – neither like mor dislike

68

Appendix Table 1. Table of random numbers

59391

99567

10363

86859

11258

58030

76364

97518

19558

24591

52098

77204

64432

51400

36863

82718

14615

25670

16706

55368

87024

27062

98342

99612

37121

82848

43918

61891

59798

94335

04190

01896

27101

32803

34936

95068

54463

16874

92494

15669

88628

47237

62677

63157

56689

35911

73800

57412

76593

35682

14530

31017

13215

91326

40844

33020

36239

31389

03505

35256

80428

71824

62233

72389

81872

39936

83671

80827

96363

35213

00116

15696

97720

11666

71628

74586

10703

15369

13841

73130

84989

65178

51259

71681

78783

23476

90637

69620

98000

75691

67104

63110

03388

35979

41632

39495

17622

13699

39719

09847

39100

53988

33423

81899

61547

40501

22518

75112

80327

45548

51089

55576

30485

02671

60251

99943

98215

62173

98191

42146

91834

83068

02132

84242

05597

41995

10798

14878

90813

48822

88931

86211

92879

49269

81366

73631

36584

22281

95451

34598

57430

73528

25991

78388

34534

82270

39559

65959

16638

12477

10421

34434

70769

09134

09965

00541

88596

64721

59980

96657

43648

54086

86413

63806

57994

75888

71693

33475

48472

59439

55049

43132

42740

39318

76330

83266

76970

37074

83712

20287

32883

80876

65198

06514

56862

43451

10237

44785

30101

69717

15579

39515

68624

78295

94420

38155

79152

98336

54656

64936

29793

74798

84481

85417

03866

40914

39357

98710

43189

27227

74216

64081

56171

26793

65988

61592

49863

75818

74951

72850

86538

08479

47750

95466

47737

27041

96001

67814

74307

54719

65172

18888

29575

13330

52056

85532

14810

10526

42664

01596

07571

70745

66192

85515

03845

27366

56760

72880

79999

28440

42271

10909

43338

38100

07819

43001

98147

93643

08062

21580

73399

34736

58904

58103

51459

21105

33863

59543

47961

47971

03280

95256

32943

83841

29882

73457

12731

11231

25878

13990

69

Appendix Table 2. Table of random numbers – permutations of nine

98119

42293

71926

17455

66834

29662

35341

84787

53578

47634

62781

19563

58857

25245

83196

75918

96479

31322

62128

39637

58873

11765

27285

93516

44949

76491

85352

74824

56945

41611

19452

25299

32777

93188

68563

87336

26316

93661

12194

57975

71782

64843

85428

38259

49537

69967

35153

24228

47815

88679

92581

71742

16396

53434

99242

26837

17798

52523

34114

73375

58486

81659

45961

24814

52498

71675

98581

37137

63226

86349

19752

45963

99952

87383

78536

33164

45775

16691

64849

22217

51428

56378

22131

73495

49769

97913

38586

61622

85847

14254

32381

69919

27778

86257

51435

93122

15644

48893

74566

21148

15466

77622

88255

93913

54874

62331

46597

39789

97297

36866

55159

72928

14312

29581

63645

48774

81433

72848

98794

51263

85426

18975

44112

39681

63557

17339

35951

62737

93289

57693

74862

19174

86518

48456

21345

41886

28622

53491

75743

87515

39259

66168

14937

92374

65455

97774

21397

49661

54246

33113

12838

88522

76989

39863

94.34

16212

77747

43585

82151

25974

68628

51436

86891

65615

98532

54358

19779

47924

31147

73483

22266

26531

71386

12463

44121

87859

59624

93998

38217

65776

12772

36396

83527

59213

64959

75834

41141

97468

28685

46622

32234

25553

14871

91485

57997

78366

63140

29719

22565

77979

66127

33813

98384

15656

84292

49438

51741

57564

61291

89656

48879

23448

36185

74722

15937

92313

62716

19143

47931

33229

75582

56864

28657

81498

84375

48346

19222

84577

37769

95118

21884

76693

52455

63931

22575

98313

46781

79698

67862

53946

84137

31229

15454

78356

54127

43718

38599

82865

61484

99632

17273

25941

85392

72575

51457

96724

48683

64968

27846

19211

33139

17996

9477

72341

46815

28624

51183

64569

35232

83758

58885

91117

72394

23931

46578

64763

85256

19449

37622

38247

93856

47919

75785

52168

19332

81571

26624

64593

84138

77347

62519

95794

11983

33622

49461

58256

26875

71165

82872

34731

15923

99488

27299

58617

66356

43444

44772

29147

82898

57113

61586

73355

95634

18461

36979

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