Variability in biophysical parameters and pollen viability in response to stress in tomato genotypes

Tomato (Solanum lycopersicon L.), is one of the most popular vegetable crop widely grown which ranks next to potato. In tropical Asia, it is an important cash-earning crop for small farmers. It is a challenge to technology, processes and resources of horticultural production to produce vegetables several times more to meet the needs, but irrigation has become a constraint semi-arid regions. Therefore, an attempt was made to investigate variability of biophysical parameters and pollen viability in response to stress in tomato genotypes at KRC College of Horticulture, Arabhavi, Karnataka. Drought was imposed 15 days after transplanting to all the genotypes in both the IW/CPE ratio of 0.40 and 1.20 treatments. Irrigation was given when the pan evaporation reaches 41.66 mm (1.20 IW/CPE ratio) and 125 mm (0.40 IW/CPE ratio) and pollen were given heat stress at 25, 30 and 35°C. Significantly maximum pollen viability was found in 1.2 IW/CPE ratio when compared to 0.4 IW/CPE ratio. The genotypes, L-30, IIHR 2274 and L-40-3 were recorded significantly maximum pollen viability and it was least in L- 17 and L-28. Photosynthetic rate was found comparably higher in the genotypes L-30, IIHR 2274 and L-40-3 compared to genotypes L-17 and L-28. Due to higher photosynthetic rate and heat tolerance the genotypes L-30, IIHR 2274 and L-40-3 able to tolerate drought and produce more yield per plant compared to the genotype L-17 and L-28.