Effects of Prior Heat Stress on the Growth and Phytochemical Contents Accumulation of Amaranthus hybridus (Linn.)

Abstract

The present study aimed at investigating the impact of abrupt heat stress on growth and phytochemical contents accumulation in Amaranthus hybridus. The treatments were as follows: control without heat treatment, seedlings subjected to heat at 45 oC for two hours and seedlings subjected to heat at 45 oC for four hours. After the stipulated time for each category, plants were removed from the Gallenkamp oven and were transplanted into other sets of thirty six pots (of 21 cm deep and 24 cm in diameter), as well as the control. The seedlings were kept in a screen house to minimise extraneous factors such as pests and rodents. They were watered daily with 200 mL of tap water in the morning and 200 mL of tap water in the evening until they were fully established. The phytochemical contents were determined at vegetative, flowering and fruiting stage using ethanolic extracts from the dried leaves of plant samples. From the results obtained, it was observed that leaf, shoot and root fresh and dry weights of the stressed plants were lower than the control plants. Exposure of the plants at different durations of heat treatment enhanced and inhibits the quantities of phytochemicals at different growth stages. From the present study it can be concluded that heat stress, on the basis of global warming in the future, will likely have overall negative effects on the growth of Amaranthus hybridus that will become more severe as the time of exposure increases and and might cause variation in the level of phytochemical constituents of Amaranthus hybridus at different growth stages.