Seed germination response of commonbean (Phaseolus vulgaris L.) genotypes to optimal and sub-optimal temperatures

Rajmash is a cool season legume crop grown during rabi season in northern India. This crop is highly sensitive to low temperature stress during seed germination and seedling establishment stage. Therefore, identification of cold tolerant genotypes is essential in rajmash breeding programme. In the present study, 37 rajmash genotypes were subjected to germination at optimal (20°C) and sub optimal (10 and 15°C) temperatures in an incubator to understand the level of variation in germination and related at low temperature. At 20°C, the 37 genotypes recorded an average value of 98.47% with a minimum value of 91.35 %; while, at 15oC an average value of 96.02% and a minimum value of 86.10% and 10°C recorded an average value of 77.13% and a minimum value of 0%. This indicated that the genotypes could tolerate cold was recorded stress upto 15°C to a considerable level while, germination was hampered greatly at 10°C. Genotypes, EC150250, EC14920 and EC14351 showed the least reduction in germination and related parameters at sub optimal temperatures, hence these were identified to be cold tolerant at seed germination stage, which however, need to be validated under field condition.