Effects of drought stress on germination and seedling growth of peanut ( Arachis hypogaea L.)

Abstract

Peanut is am essential legume and has many uses, such as producing oil, food, and fodder. However, with the negative effects of climate change, drought is one especially of the important issues that reduce the yield of peanut. Thus, in this study, the impact of drought stress on the peanut growth was investigated by using PEG-6000 to block pathways of water movement. The changes in morphological, physiological, and biochemical during the peanut growth under drought were analyzed. In the drought condition (-2 bar), the germination time of seed increased but the percentage of germination seeds decreased by approximately 50% compared to control. Besides, the shoot height, the number of leaves, the total leaf area, root length, and fresh weight were lower than that of control. Drought stress made the formation quickly of secondary xylem and phloem. Also, the process of lignification in the phloem parenchyma cell increased. These cell walls were much thicker than those in the control root. In the drought stress, the physiological and biochemical analysis showed that the content of chlorophyll a, leaf relative water content, and starch content reduced significantly in comparison to control. Similarly, the photosynthetic intensity, the activity of cytokinin, and gibberellin decreased. The reverse pattern can be seen in the content of carotenoid, epicuticular wax, proline, and total soluble sugar, respiratory intensity, the activity of catalase, auxin, and ABA activity.