Traits Affecting Low Temperature Tolerance in Tomato and Its Application to Breeding Program

Abstract

It is essential to develop tomato (Solanum lycopersicum L.) cultivars with tolerance to low temperature (LT) for reducing production cost and increasing fruit quality in winter. This study was conducted to investigate the effects of LT on 40 tomato accessions for establishing selection criteria to select accessions with LT tolerance. Tomato plants were grown in two polyethylene film greenhouses with night temperature set-points of 10℃ and 15℃. LT significantly affected the photosynthetic parameters as well as both vegetative and reproductive growth in tomato. There was a significant difference in plant height between plants grown in 10℃ and 15℃. Leaf length and width were also significantly lower in 10℃. The stem diameter was generally lower in 10℃ but 12 accessions in 10℃ had thicker stem diameter than those in 15℃. The retarded growth was due to lower photosynthetic rate in 10℃ than 15℃. Significant delay in flowering was observed among tomato accessions in 10℃. For the number of flowers, 62.5% showed the increase but 37.5% did the decrease in 10℃ among 40 tomato accessions, showing genotype specific interaction with LT. Accessions with small fruits showed reduced fruit set in 10℃; however, it was not obvious among accessions with large fruits. Interestingly, 75% of accessions showed increased chlorophyll contents in 10℃ compared to 15℃. An accession ‘VI037163’ was selected for LT tolerance based on good performance in six out of seven traits considered such as plant height, leaf length, stem diameter, chlorophyll contents, days to flowering, the number of flowers and fruit set.