Articles
BREEDING TOMATO TOLERANT TO HIGH TEMPERATURE STRESS
Article number
830_33
Pages
241 – 248
Language
English
Abstract
Three consecutive field evaluations to screen 38 tomato genotypes for tolerance to high temperature stress under spring-summer season (February to May) in 27.3 to 42.3°C range of day temperature and 13.8 to 22.9°C night temperature, the average day/night temperature being 34.5/19.2°C revealed abnormal hastening in flowering (34%), marked reduction in number of trusses/plant (35%), number of flowers/truss (25%), fruit set/truss (53%) and fruits/plant (71%) compared to that recorded in autumn-winter season under optimal temperature condition.
Of the 16 genotypes that set fruits in high temperature stress three lines viz., CLN 2413R, CLN 2116B and COML CR-7 emerged as heat tolerant genotypes considering pollen viability, pollen germinability, fruit set, fruit yield/plant.
These three lines, along with two highly heat susceptible variety Patharkuchi and Ratan were crossed in all possible combination excluding reciprocals.
The data were subjected to Haymans model of diallel analysis. Both additive and dominance genetic variance were important for fruit yield/plant and other important characters like days to flower, flower/truss, fruit set/truss, pollen viability, pollen germination, fruits/plant, fruit weight; however, dominance component was higher in magnitude for other characters.
Over-dominance was revealed for most of the characters and partial dominance for days to flower, trusses/plant and pollen viability which amply suggested the importance of non-additive genetic system for the expression of the characters influencing heat tolerance.
One or two dominant gene groups controlled the inheritance of the characters under study.
Single plant selection will not be effective because narrow sense heritability estimates for most of the characters were low.
Considering the results of the present investigation it can be concluded that selection for high temperature fruit set should be based primarily on replicated family testing in F3 and later generations.
Of the 16 genotypes that set fruits in high temperature stress three lines viz., CLN 2413R, CLN 2116B and COML CR-7 emerged as heat tolerant genotypes considering pollen viability, pollen germinability, fruit set, fruit yield/plant.
These three lines, along with two highly heat susceptible variety Patharkuchi and Ratan were crossed in all possible combination excluding reciprocals.
The data were subjected to Haymans model of diallel analysis. Both additive and dominance genetic variance were important for fruit yield/plant and other important characters like days to flower, flower/truss, fruit set/truss, pollen viability, pollen germination, fruits/plant, fruit weight; however, dominance component was higher in magnitude for other characters.
Over-dominance was revealed for most of the characters and partial dominance for days to flower, trusses/plant and pollen viability which amply suggested the importance of non-additive genetic system for the expression of the characters influencing heat tolerance.
One or two dominant gene groups controlled the inheritance of the characters under study.
Single plant selection will not be effective because narrow sense heritability estimates for most of the characters were low.
Considering the results of the present investigation it can be concluded that selection for high temperature fruit set should be based primarily on replicated family testing in F3 and later generations.
Publication
Authors
P. Hazra, S.H. Ansary, A.K. Dutta, E. Balacheva, B. Atanassova
Keywords
heat tolerance, reproductive characters, gene action, tomato
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