ASSESSMENT OF TOLERANCE TO SALT STRESS IN KENYAN TOMATO GERMPLASM

Tomato is an important vegetable crop in Kenya and the development of salt tolerant cultivars would enhance its productivity in the vast mar ginal areas of the country. This study was aimed at determining the ma gnitude of genotypic variability for salt tolerance in the Kenyan toma to germplasm. Pot experiments with 22 landraces and 9 market cultivars were laid out as a two and four replicate split-plot design in glassh ouse in Experiments 1 and 2, respectively. Salt treatments in Experime nt 1 were 0 and 5 g NaCl kg(-1) resulting into 0.5 and 9.1 dS m(-1) of the soil saturation extracts, respectively. In Experiment 2 the treat ments were 0, 4, and 8 g NaCl kg(-1) soil corresponding to 0.5, 7.4, a nd 14.2 dS m(-1), respectively. Data were recorded on agronomic and bi ochemical parameters. The germplasm showed large variation for salt to lerance. Fruit and seed production at soil salinity of 14.2 dS m(-1) d emonstrated that these tomatoes are fairly tolerant of NaCl. Osmotic a djustment was achieved by higher fruit electrical conductivity, brix a nd total titratable acidity. Low and high contents of K+, Ca2+ and Mg2 + within tomato tissues and soil, respectively, under salt treatment, confirmed competition and antagonism involving Na+ and these cations. Low Na+ and Cl- contents in the fruit at 7.4 dS m(-1) revealed their e xclusion and ensured production of physiologically normal seeds and nu tritionally healthy fruits. Two landraces 'Chwerotonglo' and 'Nyanyand ogo' were identified as salt tolerant. Comparatively, the market culti vars showed superior fruit yields despite their susceptibility to sali nity. Accordingly, tolerance of landraces in combination with superior yields of the market cultivars is suitable for tomato improvement for salt tolerance.