Water Deficit and Excess and the Main Physiological Disorders in Agricultural Crops

The comprehension of the precise water consumption of agricultural crops is a valuable tool for establishing management programs and irrigation schedules. Appropriately, the purpose of this study was to promote a bibliographic review on the main reflexes of the inappropriate use of water and what this process can promote in the establishment and development of agricultural crops. Moreover, theoretical questions were raised regarding physiological responses triggered by soil water deficit and its effect on crop growth, critical periods for water deficit, physiological responses, and their effects on the growth of main agricultural crops. Information on the misuse of water resources and its effects have presented a series of manifestations to plants and, consequently, to agricultural production, such as a production depletion, reduction of carbon fixation, nutritional deficiency, reduction of plant height, reduction of thousand-grain weight, yellowing of leaves, reduction in germination percentage, among other factors. Correspondingly, water stress can cause a drastic reduction in leaf area, productivity decrease, stomatal closure, leaf senescence, reduced roots, reduced flowering, hampering crop emergence and stability, spikelet sterility, etc. Finally, studies aimed at the consequences of poor irrigation and/or inadequate precipitation values are of high importance, mainly due to the investigative improvement on the use of water in an effective and sustainable way.