Considering increasing world population plants cultivation expanded in many poor areas. One of the most popular stress in soils is nutrient element depression. Moreover salinity and drought stress nowadays increased in the world. In order to improve plants tolerance to these conditions it necessary to realize plant mechanism under abiotic and biotic stresses. Plant tolerance to these stresses is dependent to their genetics, environmental situation and the combination of these two elements. This report gives an overview of the recent literature on the plants resistance limitation, physiological mechanism and symptoms of nutrient elements, salinity, drought and biotic stresses. The review will conclude by identifying several prospects for future researches aiming to improve the product resistance to the stress conditions. when compared to the younger leaves because of the high mobility of nitrogen through phloem. Nitrogen deficiency induces the chloroplast disintegration and loss of chlorophyll. Necrosis occurs at later stages and if nitrogen deficiency continues, it ultimately results in stunted growth and plant death.
15Plant responses under phosphorus deficiency: Phosphorus is the second important nutrient required by plants. It is an essential component of nucleic acids, phosphorylated sugars, lipids and proteins which control all life processes. Phosphorus forms high energy phosphate bonds with adenine, guanine and uridine which act as carriers of energy for many biological reactions. Plants with high growth rate require a large amount of available phosphorus which is often not found in many soils. Therefore, in an agriculture system, it is usually necessary to add P fertilizer to the soils.