This document provides information about lettuce, including: - Lettuce is an annual herbaceous plant that grows 6 to 12 inches tall and produces dry capsules with single seeds. It is commonly grown for its leaves but sometimes stem and seeds. - The main types of lettuce are green leaf, iceberg, butterhead, and romaine. They differ in leaf structure and head formation. - Lettuce belongs to the Asteraceae family and Lactuca genus. Four Lactuca species can be crossed, including L. sativa, L. serriola, L. saligna, and L. virosa. Crosses provide traits like disease resistance. - B

1. Lettuce
Submitted to: Dr. Ijaz Rasool Noorka
Submitted by: Rameesha Saleem

2. 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.

3. 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.

4. • 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.

5. 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.

6. Crosses between Lactuca sativa and Lactuca serriola can be made
easily. Lactuca serriola serves as a source of valuable traits for
Lettuce which include:
• Disease resistance
Anthracnose
aster yellows
downy mildew
Lettuce drop
• Insect resistance
Leafminer
root aphid
• Carotenoid content
• Flowering time

7. 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 resistance
corky root
lettuce dieback
lettuce infectious yellows virus
• Carotenoid content

8. 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 resistance
beet western yellows virus
broadbean wilt virus
big vein
• Insect resistance
green peach aphid
Leafminer
lettuce aphid

9. Breeding methods
Hybridization 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.

10. 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.

11. • 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

12. Production Statistics
Production in Pakistan in metric tonnes

14. 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.

15. Any
Questions