Effect of Water Stress on Yield and Physiological Traits Among Selected African Tomato (Solanum Lycopersicum) Land Races

Abstract

Expansion of tomato farming in dryland regions of Kenya has the potential to improve livelihoods and food security of rural farmers. However, the crop is very sensitive to water deficit that has made its expansion in dryland regions of the country to nearly impossible. Crop landraces have been continuously used to develop varieties adapted to abiotic stresses such as drought. In Africa, tomato has a rich genetic resource base which is largely undocumented and whose knowledge can aid in the identification of genotypes with desirable traits for breeding. The objective of this study was to evaluate the variation in response to water stress on yield and physiological traits of twenty (20) African tomato accessions from the World Vegetable Centre and the National Genebank of Kenya. Planting was done in a greenhouse in a randomized complete block design with three replications and subjected to four soil moisture levels of 100% Pot capacity (PC), 80% PC 60% PC and 40% PC. The response to water stress was mainly dependent on the genotype and reduction in moisture significantly reduced the SPAD value, leaf relative water content, stomatal conductance, the number of fruits per plant and fruit weight per plant. However, canopy temperature increased with the decrease in moisture level. Variations among accessions for fruit weight per plant ranged from 521-2404.3 g (100% PC), 421.3-2020.7 g (80% PC), 359.3-1768.3 g (60% PC) and 127.3-1487.7 g (40% PC). This variability shows the potential among the African tomato accessions for breeding drought-tolerant tomato varieties.