Flooding: Abiotic Constraint Limiting Vegetable Productivity

Abstract

Flooding is a major environmental stress that severely limits crop productivity and it has become a major problem worldwide. More than one third of the world’s irrigated area suffers due to flooding, frequently or otherwise. It may result due to heavy rainfall, faulty irrigation, unleveled land, poor drainage or heavy soil texture. Various morpho-physiological, biochemical and anatomical changes induced in root system during flooding, for example reduction in the shoot-root relative growth, Formation of thicker adventitious roots or air roots, arenchyma formation and cuboidal packing of cells enhances the longitudinal transport of gases, the major shift occurs in the carbohydrate metabolism of the plants, which move towards lactate and ethanolic fermentation to provide the required ATP. Oxygen diffusion is 10,000 times slower in waterlogged soil as compared to air. Continued flooded conditions lead to lack of oxygen in the soil, restricting respiration of the growing roots and other living organisms. Soil chemical properties also change when anaerobic conditions persist for several days. This is followed by loss of chlorophyll of the lower leaves, arrest of crop growth and proliferation of surface root growth with the retreat of water level. Plant transpiration is affected under anaerobic conditions and extended water logging results in root death due to inadequate oxygen supply.