LettuceSubmitted to: Dr. Ijaz Rasool

NoorkaSubmitted by: Rameesha

Saleem

Introduction

• Lettuce is an annual plant. • Lettuce is herbaceous plant that

can reach 6 to 12 inches in height. • Fruit of lettuce is dry capsule

filled with one seed.• It is most often grown as a leaf

vegetable, but sometimes for its stem and seeds.

• plants grown for consumption are rarely allowed to grow to maturity.

Types of Lettuce

• Green leaf Loose leaf type lettuces do not form a

compact head, and are cultivated for the tender, delicate leaves which grow from a central stalk.

• Iceberg Iceberg lettuce grows in small, dense

heads. Commonly used in salads and sandwiches and are prized for their texture and crispness.

• Butterhead

Butterhead lettuces are known for their 'buttery' taste and velvety texture, and small loosely formed heads.

• Romaine

Romaine lettuces grow as a tall head with thick, ribbed leaves.

Genetic Resources

• Lettuce belongs to the family Asteraceae and genus lactuca.• Four species of the genus Lactuca can be crossed to each

other which include :Lactuca sativa L. Lactuca serriola L. Lactuca saligna L. Lactuca virosa L.

• They are all self-fertilized diploids.

• Having 2n = 2x = 18 chromosomes.

Crosses between Lactuca sativa and Lactuca serriola can be made easily. Lactuca serriola serves as a source of valuable traits forLettuce which include:• Disease resistance

Anthracnoseaster yellowsdowny mildewLettuce drop

• Insect resistanceLeafminerroot aphid

• Carotenoid content• Flowering time

L. saligna can be crossed with L. sativa with little difficulty, but the progenies of the crosses are often completely or partially sterile. It may serve as a source of traits which include:

• Disease resistancecorky rootlettuce diebacklettuce infectious yellows virus

• Carotenoid content

Lactuca virosa can be crossed with Lactuca sativa but the F1 hybrids are highly sterile. But can be made fertile by applying colchicine and hence making amphidiploids. The traits contributed include:

• Disease resistancebeet western yellows virusbroadbean wilt virusbig vein

• Insect resistancegreen peach aphidLeafminerlettuce aphid

Breeding methodsHybridization is a technique most often used in a crop breeding

program. Principal breeding strategies used to improve the crop include :

Pedigree method.Backcross.Mass selection.

However, Attempts to produce F1 hybrids commercially have not been successful because:

Lettuce pollen is heavy and sticky, and is not transferred by wind.

dearth of pollinating insects for lettuce plants.Hand pollination cannot produce large numbers of

seeds.

Production Technology

• Climate Lettuce is adapted to cool growing conditions with the

optimum temperatures for growth of 60 to 65F. At 70 to 80F, the plants flower and produce seed. Optimum germination is at 70 to 75F.

• Soils and Fertilizers The crop does best on fertile, high organic matter soils that

have good water-holding capacity. The pH should be 6.0 to 6.7.

• Spacing Row to row distance is 32 to 42 inches. Plant to plant distance is kept 12 inches.

• Planting the Crop Lettuce can be either transplanted or seeded. But in our climatic conditions transplants are more favorable. Plant the seed 1/4 to 3/8 inch deep at temperatures of 15 to 20C.

• Harvesting Lettuce will be ready for harvesting in 70 to 80 days after seeding or 60 to 70 days after transplanting

Production Statistics

Production in Pakistan in metric tonnes

Uses

• Leaves are found in salad mixtures and sandwiches. • In china and Egypt stem of lettuce is consumed.• A cigarette without nicotine is made from lettuce

leaves.• Edible oil is extracted from seeds of lettuce.• Lactucarium, the dried latex produced from a wild

lettuce relative, Lactuca virosa L. is used to make a sleep-inducing medicine.

Any Questions