"A world population is 7.3 billion and by 2050 it is expected to reach 9.7 billion while as at the same time agricultural productivity is poorly exaggerated due to the mounting environmental constraints as a result of climate change. One of prevalent environmental stress encountered by plants during their important growth stages is the heat stress. Heat stress is defined as a period in which temperatures are hot enough for a sufficient period of time to cause irreversible damage to plant function or development. Exposure to heat stress for prolonged periods can even result in plant death. Plants can be damaged by either high day or high night temperatures and by either high air or soil temperatures. Predictions indicate that temperatures will intensify by another 2-6°C by the climax of this century and likelihood to induce heat stress more frequently and severely, begetting to serious reduction of crops yield. The genetic basis of heat adaptation is poorly understood. Conventional breeding methods have met with limited success in improving the heat stress tolerance of important crop plants through inter-specific or inter-generic hybridization. Therefore, it is imperative to accelerate the efforts for unravelling the biochemical, physiological and molecular mechanisms underlying heat stress tolerance in plants"-- Provided by publisher.