• Water relations: Drought alters the water status by its influence on absorption, translocation and transpiration. The lag in absorption behind transpiration results in loss of turgor as a result of increase in the atmospheric dryness.
• Photosynthesis: Photosynthesis is reduced by moisture stress due to reduction in photosynthetic rate, chlorophyll content, leaf area and increase in assimilates saturation in leaves (due to lack of translocation).
• Respiration: Respiration increases with mild drought but more severe drought lowers water content and respiration.
• Anatomical changes: Decrease in size of the cells and intercellular spaces, thicker cell wall and greater development of mechanical tissue are the anatomical changes. Stomata per unit leaf tend to increase.
• Metabolic reaction: Almost, all metabolic reactions are affected by water deficits.
• Hormonal relationships altered: The activity of growth promoting hormones like cytokinin, gibberlic acid and indole acetic acid decreases and growth regulating hormone like abscisic acid, ethylene etc. increases.
• Nutrition: The fixation, uptake and assimilation of N is affected. Since dry matter production is considerably reduced, the uptake of NPK is reduced.
• Growth and Development: Drought results in decrease in growth of leaves, stems and fruits. Maturity is delayed if drought https://www.woolcool.com/valtrex-online/ occurs before flowering, while it advances if drought occurs after flowering.
• Reproduction and grain growth: Drought at flowering and grain development determines the number of fruits and individual grain weight, respectively. Panicle initiation in cereals is critical while drought at anthesis may lead to drying of pollen. Drought at grain development reduces yield while vegetative and grain-filling stages are less sensitive to moisture stress.
• Yield: The effect on yield depends on what proportion of the total dry matter is considered as useful material to be harvested. If it is aerial and underground parts, effect of drought is as sensitive as total growth. When the yield consists of seeds as in cereals, moisture stress at flowering is detrimental. When the yield is fibre or chemicals where economic product is a small fraction of total dry matter, moderate stress on growth does not have adverse effect on yields.
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