Plant Response and Water Use Under Single and Combined Abiotic Stresses: Salinity Drought N and B.

Arid regions face increasing salinization of water resources and depletion of fresh water. Salinity and drought are the major abiotic stresses impacting agricultural production in arid regions and they often occur together. Current guidelines recommend extra leaching when irrigating with saline waters and some studies recommendation that extra N alleviates some salinity stress. These factors serve to increase the risk of increasing drainage volumes and nutrient loading to receiving waters. Understanding the interaction of abiotic stress on crop production is thus essential for management and optimization of resources. We evaluate plant response and water use efficiency (WUE) to individual and interactive effects of salinity, drought, nitrogen and boron stress.

Almost all plant abiotic response studies and recommendations are from single stress experiments. Under field conditions there are often multiple stresses occurring simultaneously. The various models dominant stress response, adding the individual matric and osmotic potential, adding the response without interaction and multiplying individual response to represent multiple abiotic stress are evaluated, leading to the conclusion that the multiplicative model appears to best represent the limited data available. Further under saline conditions, less not more N satisfied the plant requirement. Most reports showing benefit of extra N consider only saline treatments with current nutrient practices and saline with added nutrients, thus minimal requirements under non-stress conditions are not determined. Evaluating WUE in terms of water consumed, drought stress and salinity reduced WUE rather than increasing it, thus under drought conditions greatest yields are achieved by providing adequate water to reduced acreage.