Abstract

Wheat (Triticum aestivum L.) is a winter season crop and India holds second rank in production globally. Several reports have supported the facts that heat and cold stress adversely affect the germination, crop growth and development. Terminal heat stress is a major problem for wheat production which severely affects the grain yield. Two wheat genotype viz. WH 730 (heat tolerant) and Raj 4014 (heat intolerant) identified from previous field experiments were selected to study the effect of heat and cold treatment on the germination and growth at early stage. High temperature stress was imposed by exposing soaked seeds to 35 and 40°C temperature for 6 h. On the other hand for cold stress, seeds were exposed to 0°C for 2 h. Results indicate that heat treatment at 35°C had no significant effect on germination efficiency of the genotype WH 730, while same was reduced in the genotype Raj 4014 after 24 and 48 h of heat treatment. Germinated seedlings exposed to 35°C showed improved vigour over control seedlings of both genotypes. The genotype WH 730 which was heat tolerant at grain filling stage had longer shoot and root relative to Raj 4014 during growth at early stage (13 days after heat treatment). At 40°C, the germination was poor and both genotypes could not grow under hydroponic conditions. Furthermore, when both genotypes were checked for cold tolerance, null effect was observed on the germination (24 and 48 h post cold treatment) but the growth of the genotype WH 730 at early stage (13 days post cold treatment) was found to be vigorous as compared to Raj 4014 which was drastically reduced by cold treatment and could not hold longer under hydroponic condition. The study showed that the genotype WH 730 which was tolerant to terminal heat stress has also shown tolerance during germination and growth at early stage under both heat and cold stress.

Key words: Heat treatment, cold treatment, hexaploid wheat, hydroponics, tolerance.