6.5Heat StressAs every plant has an

6.5Heat StressAs every plant has an optimum temperature for growth and development,temperatures out of the optimal range (higher or lower) could potentially beharmful for plants. The most evident consequence of global climate changes is theincrease of temperature in several agro-climate zones. High temperature cangenerate heat stress to plants. This phenomenon negatively affects agriculturalproductivity. It has been proved that exposure to high temperatures reduces cropyield owing to a shorten life cycle and accelerated senescence [129].Plants have the ability to respond to heat stress by inducing several and diversemechanisms. The most common adaptive response to heat is the production ofprimary and secondary metabolites as well as heat shock proteins. The role of NOin heat-stressed plants is to react with proteins, activating different signaltransduction pathways, mainly by inducing the production of antioxidant enzymes. Furthermore, some studies note the enhanced ability of NO in other biologicalprocedures, including photosynthesis, and the induction of other heat stress factors[46,130].