High temperature stress is one of the stresses, which adversely affects crop production. Being grown in narrow
temperature range, a slight increase in the temperature will drastically reduce the yield of rice. It is important to study
the impact of temperature stress, on seed yield attributing characters so as to develop mitigation strategies. Hence, the
present investigation was carried out by raising five rice varieties viz., MDU 5, ASD 16, CO 51, Anna (R) 4 and ADT 43
in field condition at Coimbatore under two temperature regimes-high (summer, 2016) and normal (rabi, 2016)
temperature in field condition, so as to explore its impact on crop phenology and seed yield. Except for plant height no
significant influence of high temperature on vegetative growth of the plants were observed. Increased plant height was
observed in case of high temperature conditions. Reduced leaf area and leaf chlorophyll index were also observed.
Exposure of plants to high temperature also resulted in early flowering in all the varieties under testing. Total number of
spike lets per panicle, number of filled seed per panicle and seed set were significantly lower in plants exposed to high
temperature which ultimately resulted in lower seed yield.
