The interactive effects of drought and heat stress on photosynthetic
efficiency and biochemical defence mechanisms of Amaranthus species
Drought and heat stress are major abiotic stress factors that limit
photosynthesis and other related metabolic processes that hamper plant
growth and productivity. Identifying plants that can tolerate abiotic
stress conditions is essential for sustainable agriculture.
Amaranthus plants can tolerate adverse weather conditions,
especially drought and heat, and their leaves and grain are highly
nutritious. Because of these traits, amaranth has been identified as a
possible crop to be grown in marginal crop production systems.
Therefore, this study investigated the photochemical and biochemical
responses of Amaranthus caudatus, A. hypochondriacus,
A. cruentus and A. spinosus to drought stress,heat shock
treatments and a combination of both. After six-leaf stage in a
greenhouse, plants were subjected to drought stress, heat shock
treatments and a combination of both. Chlorophyll a fluorescence
was used to evaluate the photochemical responses of photosystem II to
heat shock while subjected to drought stress. It was found that heat
shock and a combination of drought and heat schock damages photosystem
II, but the level of damage varies considerably between the species. We
concluded that A. cruentus and A. spinosus are more heat
and drought tolerant than A. caudatus and A.