The Effect of Triple tensions Drought, Salinity and Nitrogen Deficiency on Water Absorption in Tomato Plants.

Optimal management of irrigation water and optimal use of food under salinity and drought is very important. The objective of this research was assessment root water uptake function of tomato under simultaneous water, salinity and   different levels of nitrogen stresses. The experiments were carried out on tomato plant in a factorial randomized complete block design with three replications. The treatments consist four levels of water irrigation (50, 75, 100 and 100 percent of water requirement), Six levels of salinity (1, 2, 4, 6, 8 and 10 dS/m) and three levels of nitrogen including zero, 50 and 100 percent of the fertilizer needs. Water, salinity and nitrogen stresses treatments were applied from the flowering plant. .The results showed under simultaneous salinity and nitrogen stresses, modified MB model and under simultaneous water and salinity stresses, MB-H, MB-F,MB-D and MB-VG models had better accuracy and MB-F Model in comparison with other models had the best fit against the measured data. In simultaneous water, salinity and nitrogen stresses multiplicative MB-MB-F model is the best fit than other suggested