A physiological and genetic study of outdoor tomatoes, lycopersicon esculentum mill.

The tomato, Lycopersicon esculentum Mill, is of sub tropical origin and at temperatures below 15C growth and development is impaired. In this study this was evident from chlorosis, anthocyanin pigmentation and low growth rate observed in plants grown under controlled environment regimes and in field trials. Tomato cultivars are thus at present not well adapted for outdoor production in the U.K. This study was directed at investigating the response to temperature and inheritance of characters which are relevant to outdoor tomato production. Variation between cultivars in the response of vegetative characters to temperature was found to be low. Differences between cultivars in unit leaf rate and leaf area ratio were found but these were compensatory and relative growth rate was similar in the cultivars grown at low temperatures. A large response to temperature and genotype x environment interactions were found in the number of days to flowering; therefore this was examined in detail. The relationship between the number of days to flowering and vegetative development was found to be influenced by temperature, and differences in the pattern of distribution of 14C labelled assimilate between a late and an early flowering cultivar were present. The inheritance at the time of flowering, fruit set and yield were investigated in the F1 progeny of a diallel cross, which were grown in 2 environments. The level of dominance differed between the environments and the implications of this observation are discussed. The time of flowering was also examined in the F2 progeny from crosses between genotypes which exhibited extreme values for characters associated with earliness. Amongst these plants recombinants were identified which were early flowering.