HYBRID SEED PRODUCTION IN TOMATO

CLIMATE Grows best in the warm and dry season Day temperature 21-25°C Night temperature of 15-20°C Temperature ˃ 30°C and ˂ 10°C is not favorable Relative humidity 60-70℅

Planting and Spacing Seed of male parent should be sown 2-3 weeks earlier to ensure adequate supply of pollen Planting ratio 5:1 Spacing – Female line = 80 x 60 cm – Male line = 60 x 40 cm

ISOLATION Isolation of male and female parental lines is not necessary Seed production field of two hybrids should be isolated by 25 m

Hybridization technique Emasculation – Days before pollination

Male sterility First time used by Prof. C.M Rick 1945 Types – Sporogenous male-sterile mutants – Functional male-sterile mutants – Photoperiod sensitive male-sterile mutant – Temperature dependent male-sterile mutant

Sporogenous male-sterile mutants Not determined – Point of arrest in pollen development has not yet been determined Premeiotic – Pollen mother cell collapse or abort prior to meiotic phase Meiotic – Abnormalities in tapetal cell

Continued….. Tetrad – Meiosis completed before pollen abortion. Tapetal cell fail to expand to normal volume producing small locules at anthesis. Microspore – Pollen abortion after microspore formation – Microspores do not enlarge

Functional male-sterile mutants Cleistogamous mutant – Petals fails to open Dialytic mutant – Growth of epidermal hairs on the anther surface is prevented. Exserted stigma mutant – Due to excessive length of style.

Continued…… Positional sterile mutants – Overlapping or curling of petals – Holds the anthers in close contact with pistil Positional sterile-2 mutants – Characterized by the presence of fertile pollen and indehiscent anthers

Photoperiod sensitive male-sterile mutant 100% male sterility in long days (LD 12 h day length) Male fertility in short days (SD 8h)

Temperature dependent male-sterile mutant Better fruit and seed set at 12°C than 24°C.

Pollination 8:00 to 11:00 am 2 to 3 days after emasculation

Fruit production No. of fruits to be kept depend on fruit size of female parent – 30 fruits for large fruited (80 g) – 40 fruits for medium fruited (70-80 g) – 50 or more fruits for small fruited (60 g or below)

Harvesting Ripened about DAP Harvested at red ripe stage

Hybrid seed yield One kg fruit yields 2.5 to 4 g hybrid seed Determinate growth kg seeds/ha Indeterminate kg/ha