Gerbera: practice & theory

Dr. Yoseph Shoub

©copyright by the author

In our gerbera breeding farm in Israel we breed gerbera

varieties for countries with climate similar to yours.

We develop advanced growing techniques for soil and for hydroponics,

and we guide our growers via questions and answers.

This lecture is part of our efforts to support the growers.

www.gerberaisrael.com gerbera1@zahav.net.il

At several locations in different countries we hold varieties’ trials.

We do it with the cooperation of our producers “ Selecta”.

www.selectaworld.com

The morphology of the gerbera

The stem

Includes: 4 mature leaves

2 flowers

1 new productive bud

2 dormant buds

on each stem:

4 mature leaves (1 - 4)

2 flowers’ stems (each one is ~ 700 mm. Long)

1 new productive bud

2 dormant buds

2 flowers’ stemsproductive bud

each stem is ~ 5 mm. long

(4 Internodes of ~ 1.25 mm.)

scheme of A gerbera branch

built of 4 stems

1’

2’

3’

4’

old mature leaves (1’ - 4’)

scars of 2 picked flowers

*Seedling: a plant

originated from seed, used in the breeding process.

`Gerbera seedling *

4 mature leaves

3 juvenile leaves

short stem of ~3mm

Gerbera plantlets ready for planting. At this stage, all the leaves are juvenile leaves.

The leaves

Mature leaves at different ages

‘Reading’ the plant phenotype* helps to reach the right professional decisions.

* The plant phenotype is the unique form of a variety.

Active leaf

Normal aged leaf, already contributed its content.

Changes in the minerals content, cut the leaf activity.

active leaf

early changes in the minerals content

Same leaves, bottom side

Something is wrong !

What do we tend to assume ?

Gerbera seedling 6 weeks after replanting. A branch with 2 flowers

and a new young stem.

Regarding flowering The gerbera is: ‘Self inductive plant’.

Flowering is not affected by the length of the day, nor by the temperature.

A new young stem

A seedling 10 weeks after replanting, already has more than 2 stems.

Mature gerbera plantsWhat about leaves thinning

and optimal leaves number?

The crown

3 exposed growing centers

view from above

A live tissue of compressed stems

Scars of: detached flowers stems

As a perennial wild plant, more growing centers are developed and turn into

semi-independent plants.

detached leaf

The crown

Adventitious root

Secondary roots

view from aside

In the photo - Adventitious roots of Polygonum sp. which have been formed while the green stem was covered by a wet soil.

Adventitious roots are formed from the stem, and not from another root.

The roots system of the gerbera, is consisted of two roots’ types:

A. Adventitious roots The main roots, formed only on young stems, close to the soil surface.

B. Secondary roots The white rootlets, formed only on the adventitious roots.

Adventitious roots

The roots Soil surface*

* The soil surface is a sensitive level, regarding temperatures, water holding, evaporation, drying up, EC, pH, etc.

The white rootlets supply Oxygenated water and

minerals solution via the root tips and the root hairs.

"Let us grow roots, the flowers are the by-products"

(This is the whole practical truth)

Young root system

Adventitious root

Secondary roots

In containers, the appearance of the outer white rootlets, reflects the situation of the roots inside.

Washed roots system of

a gerbera plant

grown in container.

.Use a shovel, for uprooting the roots.

Established roots system of an Israeli variety, in Ecuadorian soil.

‘Old’ crown

Contaminated scars of flowers’ stems

And water supply via ‘rusty’ tissues

Continuity of growth

in spite of the :

semi independent new branch

New roots are able to emerge from

a healthy gerbera young stem,

in spite of the older roots’ condition.

Variety - Province

Bree

ding

cod

e

The Flowers

Variety - Lorca

Flower bud as first seen at bottom of the leaves.

At this phasethe flower stem is not visible.

by botanical definition

The gerbera ‘flower’

is an inflorescence.

Stem elongation upwards starts at the base of the young stem .

The flower bud grows upwards.

Stem elongation

The elongation process of the stem is not symmetric .

One side grows and elongates faster than the

other side .

This growth pattern is directing the flower head

downwards .

++

+

As long as the flower head is located among and under the leaves, the stem continues to grow in non-symmetric pattern.

This kind of growth protects the flower head until it passes the leaves.

Than the growth turns, the stem and the flower head will continue to grow upwards.

+++

The flower head just passed the edges of the leaves.

Flower head among the leaves.

Maturation of the ‘Flower-stem’

Or when not to harvest gerberas *

Maturation (lignifications) of the gerbera ‘flower stem’, starts at the stem’s base, and continues upwards, following the stem elongation.

At the same time, downward lignifications at the stem’s tip, continues only a few centimeters and than stops .

As long as the elongation process continues, the elongation sites remains flexible.*

* Do not harvest gerbera flowers during this flexible stage !

stem base

Stem tip

In our breeding program, we pay attention to such stem qualities as - length, strength, early lignifications and longevity.

At early stages, the petals develop in non symmetric pattern, and this is normal.

Cross section of gerbera inflorescence, ready for harvest !

At least 2 full circles of ripen male flowers are seen!

Female flowers, male flowersfemale flower, male flower, bractreceptacle

stem tip

petal

Single type flowers

Ligulate female flower

Tubular flowers

Male femaleMale females

Double type flowers

All are ligulate flowers

male females

Single type flower,

‘Female stage’.

Not ready for harvest,

the stamen are not yet visible.

Stigma

Pistil and

Same flower

two days later:

Ready for harvest,

‘Male stage.’

Stamen and pollen

2 circles of male flowers are open .

Post harvest treatment - essential and simple: saturation with post harvest solution.

Our varieties grown in soil - Ecuador

Leading lines for harvest: • Harvest during the cool hours of the morning.• Pick only mature lignified stems. • Pick only when two circles of male flowers show their stamens. • Cut the stem base and immerse immediately in post harvest solution. • Transfer the flowers’ containers to cool packing area as soon as possible.

Packing

30 mature gerbera flowers packed for shipment

Open tray, designed in Israel, for 30 gerbera flowers.

Note - the side holes are touching the walls.

Top Bottom

Tray ready for packing, 2 trays packed in one container. 60 flowers per container.

Top

30 packed flowers

The other side of the same tray

Essential preparations before packing ‘Bunching’

Bunches of one tray, are laid beneath the second tray.

The tray’s top is tied to the container head

The container is ready to be covered

Stems packed in the container, and laid horizontally during the

storage and the shipment, will react, after the arrival, with active

Curved growth.

active curved growth

Storing and shipping the packed gerbera containers, in upside-down

position, helps to avoid the phenomena.

Important Note -

5 Major questions about fertigation of intensive crops:

• When to irrigate• How much to irrigate• When to fertilize• How much to fertilize• Which fertilizers to use

‘Fertigation’ = Irrigation with fertilizers

A few words about the importance of water and Oxygen

Oxygen plays an important role in the life of plants as for all living things.

The fact is that plants are able to use the vital Oxygen only when

it is dissolved in water, and water, for the plants, is the only Oxygen supplier.

By irrigating, we are supplying Oxygen, water, and minerals, all needed for optimal growth and production.

Note the descending order of importance – Oxygen, water, all the other minerals.

With higher oxygen rate in the soil solution

the plants are able to absorb fertilizers without difficulty,

even if the concentrations of the minerals are low.

About 11 to 8 ppm O2 is almost the higher possibility rate for O2 to dissolve in water (at sea level), for temperatures of 12 – 27C (the optimal range for gerbera Growth).

Stagnant water (reservoir water), contain less oxygen than fresh water.

Water of high temperatures (35 - 40C), contain less Oxygen than cool water.

O2 molecules dissolve into the water, through the surface of the water.

The greater the surface area of the irrigated water, the higher the amount

of O2 dissolve in it.

Water surface and Oxygen availability

Therefore drip irrigation systems increase the Oxygen rate in the soil solution, compare to other traditional irrigation systems.

For the same reason, Micro drip irrigation systems are excellent Oxygen suppliers.

With micro drip irrigation e.g. 200cc / hour (A), more O2 is dissolved into the solution.

With conventional dripping 2000cc / hour (B), less O2 is dissolved into the solution.

A B200cc / hour 2000cc / hour

The above data is a result of the physical fact - that the total number of drops, for the same water volume, is greater with micro dripping, than the total number of drops of conventional dripping.

Thus, the area surface of micro irrigation is bigger and so is the amount of O2 dissolved in it.

Drops.…

Micro flow

“In one drop of water, there is a degree of perfection, greater than in any machine designed by man”.

Albert Einstein

Water movement in the soil is affected, in addition to other factors, by the

rate of the water flow.

Micro irrigation is changing the gravity movement character to a diffusion

movement.

Water movement in the soil

Slow water movement 200cc / hour

Fast water movement 2000cc / hour Salts accumulation‘Piston’ movement

Micro drip irrigation

Creates diffused water movement, and helps to avoid salinity in the roots zone.

Conventional drip irrigation

Creates gravity water movement and enable salinity conditions to develop .

)gravity()diffusion(

Fertigation

timing and quantities

When to irrigate plants and how much, depends on the following factors:

A. The amount of water used by the plants from the previous irrigation, plus the amount of water evaporated from the soil surface .

B. The saturation point of the soil or the media, and the drainage quantities from the roots zone.

[A & B are easily measured and controlled by sensitive electronic tensiometers]

C. The minerals content of the water in use (EC).

D. The accumulated salts in the soil solution and in the drainage (EC).

]C & D can be measured and controlled automatically by sensitive electrodes.[

E. The sensitivities of the plant variety, regarding salinity, pH, aeration, etc.

An example for summer time:

If the daily transpiration rate of a mature gerbera plant (including the evaporation)

is ~ 500cc therefore the effective amount of irrigated water on such days, should

be ~ 625cc per plant.

Calculation:

The transpired 500cc + 125cc needed for leaching the excessive salts = 625cc.

This irrigation quantity, can create 20% drainage.

The daily irrigation quantity

)The data below are solely for the purpose of the discussion.(

How frequently to irrigate

How frequently to irrigate depends on the soil or the media character, on the water quality, on the plant activity, and on the irrigation system in use.

In sandy soils, for example, it is advised to divide the daily amount of water,for 2 or more irrigations, and in clay soils to irrigate once a day or less.

If the EC of the original water is above 0.8mmhos/cm, it is advised, as for the risk of salinity, not to let the soil surface to dry.

As for the timing of the first daily irrigation, it is advised to follow the transpiration rates, which normally increases about 1 - 2 hours after sun rise.

‘Auto Agronom’

With the newly accurate irrigation control system – the ‘AutoAgronom’, the daily amount of water is divided automatically to many small pulses. These irrigation pulses are controlled via very sensitive tensiometer, affected by the water consumption of the plants.

The purpose of these small irrigation pulses is to keep the water tension

in the soil close to the saturation point of the soil, and by that to keep the

continuity of optimal growing conditions around the clock.

Auto Agronom by Rotem Dan (88) Ltd, Israel rotem_d@zahav.net.il htpp//rotemdan.com

. The Auto Agronom system:

• Controls the amount of water in the soil / media, close to the saturation point.

• Measures and controls the the Nitrates, the EC, and the pH, in the irrigation water and in the roots’ zone solution.

• Enables diffused water-movement in the soil, instead of gravity water-movement. • Is able to create optimal growing conditions for the white rootlets, by increasing the Oxygen rate, at a reduced soil volume (from the soil surface to

a depth of 10 - 20cm). This soil volume is optimal for managing high plant activities, and at the same time, saves fertilizers and water, and avoids salinity.

The ‘Auto Agronom’ technique fits many kinds of soils and crops.

Therefore, it is already in use in soil farms (indoors and outdoors) and in hydroponics farms of:

Roses, Gypsophila, Carnations, Gerberas, Tomatoes, Pepper, Citrus, Avocado and some other flower crops.

It is already installed in countries like: Ecuador, Colombia, Mexico, Australia, Tunisia, and of course in Israel.

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Mili

Bars

0.0

20.0

40.0

60.0

80.0

100.0

120.0

Tem

p.+H

umid

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Tens.1 %Humidity Temp Oxy

‘Auto Agronom’ graphs :

Daily irrigation pulses, Humidity, Temperatures and Oxygen.

Gerbera Breeding ltd. Ganey Am, Israel (14/ 09 / 2005).

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Mili

Bar

s+ec

+ph

565758596061626364656667

NO

3 P

PM

EC pH EC Line NO3 Linear (NO3)

‘Auto Agronom’ graphs: Daily data of: EC.(irrigated water and soil solution), pH, and NO3.

Gerbera Breeding ltd. Ganey Am, Israel (29/ 07 / 2006).

Auto Agronom results in Coco peat media Gerbera breeding , Israel. April 2005

.

Autoagronom results in soil

Pepper - Israel January 2005

8 –

9cm

The source of the Oxygen used by the plants, is O2 molecules dissolved in the water.

Absorbing water by the roots means Oxygen supply.

And we already said it !

Feeding

A. Oxygen

Oxygen is involved almost in all the physiological processes in the plant. Therefore, it can be considered as the most important element for the plants.

A. for minerals + microelements B. for minerals + Calcium C. for acids

C AC

Experimental

AB

3 tanks system B. All the other minerals

Feeding formulas

A. An average common used Feeding formula for gerbera (750 – 1000 gr. Fertilizers / 1000 Liter).

B. Feeding formula in ‘Gerbera Breeding’ Israel (250 – 400 gr. Fertilizers / 1000 L = ~ 70% saving).

Net fertilizers Acidity Macro elements Micro elements E.C. pH N P K Ca Mg S Fe Mn Zn Cu Bo Mo

A. (common used formula)

0.8 - 1.3 5.5 - 6.5 (ppm)170 30 220 100 40 60 2.0 0.28 0.26 0.06 0.5 0.03

B. ( saving formula)

0.3 - 0.5 5.5 - 6.5 (ppm) 45 12 60 80 40 60 1.8 0.22 0.24 0.10 0.3 0.01

Frequently drip irrigations and suitable pH , help the roots’ system to absorb the minerals; Because of their availability and the presence of Oxygen.

Salinity conditions endanger plants life

‘SALINITY’ is a situation in the roots’ zone, when salts accumulate above the ‘Normal’.

The presence of the excess salts is causing physiological and physical damage to the roots and to the above soil organs.

Early detection of developing salinity conditions, and professional treatment, can avoid the economic damage.

Early detection of developing salinity conditions, is possible only by using accurate electronic devices e.g. tensiometers, electrodes and other accurate sensors.

Browning and roots burning

Difficulties in water uptake

Stages of

salinity damage

in gerbera

Flower stem becomes shorter

Weakening of apical dominance

Sensitivity to diseases increases

Minerals accumulate in the leaves and Normal growth stops

Flower diameter is reduced

Development of vegetative buds

Economic crisis !!!!

Intensive crops such as gerbera, react positively to rich feeding formulas .

However, at the same time and especially in hot countries ,

gerbera plants are very sensitive to accumulation of excessive salts in the

soil solution, and in the plants organs.

Being ‘Master’ in the art of growing intensive crops, is to find the right

optimal way of supplying oxygen, water and minerals, and avoiding

salinity risks, at the same time.

Washing the soil

Irrigating with an overdose quantity of water, at regular times,

is a common technique to avoid salinity damage.

However, it is not logical to ‘wash’ regularly, when irrigation is controlled

by sensors as: tensiometer, EC and pH meters.

.Intensive irrigated agriculture, and techniques such as washing the soil, mean simply - leakage of minerals that pollute our water.

Gravity water-movement below the drippers, creates in the soil-beds, the so called, wetted ‘Bulb shapes’ (Normally not seen by the growers). Continuous seasonal fertigation creates ‘Salinity fronts’ around the ‘bulbs’.

Diffusion of minerals brings salts to the soil surface on top of the salinity fronts, shown in the previous slide.

Salinity damageNormal

Salinity damage

0

50

100

150

200

250

300

CLCaKPN

%

Under salinity conditions, minerals accumulate in the leaves above the ‘normal’.

%

N P K

‘Normal’ Accumulated

‘Normal’ 1.5 0.22 3.3

Accum. 3.9 0.50 4.5

Gerbera Breeding, Israel

Leaves analysis

Salts accumulation in the leaves

Salinity + fluoride damage

Air Temperatures -

Temperatures between 8 to 38C are possible range for growth & blooming.

Day temperatures between 17 - 34C are sufficient for normal growth & blooming.

Day temperatures of 17 - 27C are optimal for high quality growth & blooming.

Night temperatures of 12 -17C are optimal for high quality stems & flowers.

Night temperatures of 20 - 22C and above, decrease flowers & stems qualities.

Night temperatures of 8 - 10C for long period delay growth and produce malformed flowers.Night temperatures of 0 - 4C for long period stop the growth and cause plant death.

Soil Temperatures – Winter soil temperatures of 18 - 20C at soil level (0 -17Cm), are optimal for the development and the activities of the white rootlets.

Temperatures

Humidity

Relative - Humidity

The optimal relative humidity range for gerbera growth, is within 60% to 85%.

At this optimal range, the plants transpire, absorb water, minerals and CO2 without any difficulties.

As a result, greenhouse gerberas develop properly and produce a lot of quality flowers. On the other hand, Low relative humidity, can cause as much damage as salinity.

Without Humidity and temperature control

and temperatures up to 32C.

Flower of plant grown at :

Humidity up to 80%

Salinity and Low Humidity damage

Low relative humidity affects the growth of gerberas as negatively as salinity.

Under salinity conditions: Salts accumulate in the root zone.

causing damage to the root tips

and preventing further root growth .

Causing difficulty in water uptake.

Under Low Relative Humidity,

or Salinity conditions : Transpiration rates are higher than

what the roots are able to supply.

Healthy plants than regulate transpiration by closing the stomata

When stomata are closed, the following processes occur in the leaves:

Physiological Physical & chemical

CO2 absorption is prevented Humidity at leaves level decreased

Photosynthesis is eliminated Leaves temperature is raised

Less sugars, more salts Salts concentration is increased

physiological results

Limitation of energy sources lead to weak growth.

Accumulation of retarding compounds in the plant organs.

Agricultural results

No bud breaks, no growth of new branches, no roots, no flowers,

Poor production, poor quality, increasing sensitivity to diseases.

Air movement in the greenhouse throughout the high humidity night hours, is

aimed at avoiding Botrytis damage.

Higher relative humidity 85% to 95%, for 7 to 10 hours ,under low temperature conditions, are optimal for Botrytis development

Natural light is very important factor: It activates photosynthesis, increases water and minerals consumption, affects growth production and qualities, increases plants resistance to diseases, and more.

Light

April – May

Gerbera production as affected by Israeli light

Automatic shading

Shading – who needs it

Automatic folding

Our varieties are selected under these light conditions

Unnecessary permanent use of black ‘saran’

Israel 1963 - The first year of gerbera production. Can you count the mistakes?

Common practice mistake of beginners: Low flat soil beds resulted in other related growing problems.

Unnecessary plants Chlorosis

The chlorosis indicate probably, that the number of the white rootlets, of this variety, in this soil bed is limited. It does not indicate about deficiencies, as we tend to assume.

Is it possible to change it ?

Yes, it is!

High raised beds are precondition for gerberas in soil

30cm is the minimal bed height for optimal drainage and

aeration.

Increasing the soil surface of the beds, is important also

for seasonal heat accumulation in the soil.

Soil beds for one plants-line

dripping lineplants

Raised soil beds for two plants lines

45cm 11 40 13 13

Sizes :

Height - 45cm .

Width - 66cm. (upper level)

Pathways - 45cm .

Slopes - 11cm .

Plants line - 13cm. from bed shoulders .

Between plants lines - 40cm.

In the line - 20cm.

Dripping tubes, inside the bed close to the plants .

Preparations for the coming season: A. Cutting down the foliage

B. Loosening the soil beds

C. Subsoil ploughing

D. Raising soil beds for one plants line

E. Fumigation (Methyl Bromide). Disinfection (Edigan, Condor and others)

Nematodes are real problem for gerberas grown in soil. Especially if we plan to grow them more than one season.

4 liter plot, Gerbera breeding Ganey Am Israel

Growing in containers, so called, Hydroponics

New varieties trial

4 liter

17Cm

21 Cm

13.5Cm

Seedlings in 1.5 liter containers

Gerbera breeding Ganey Am Israel

5 liter plastic bags – Colombia

With our varieties

Our varieties grown in soil - India

Our varieties grown in hydroponics - Colombia

A. Potential Fungal Diseases Botrytis cinerea Phytophtora cryptogea Sclerotinia sclerotiorum Oidium (Mildew)

B. Mites Tetranychus urticae Polyphagotarsonemus latus

C. General Insects Aphids spp. Trialeurodes vaporariorum & Bemisia tabaci (White fly) Frankliniella occidentalis (Thrips) Liriomyza trifolii (Leaves miners) Spodoptera littoralis (Caterpillars)

D. Nematodes Meloidogyne spp.

List of main Pests & diseases

Sprayer

Blower type