Effect of KNO<sub>3</sub> fertilization and rootstock on grapefruit response to reclaimed, salinized water

Abstract

During the last 50 years world irrigation has doubled while water withdrawal has tripled, leading to a global water crisis. As a result, growers around the world are forced to utilize effluent water for irrigation. In Israel the main source for such water is SHAFDAN, i.e., tertiary-treated waste water, which is characterized by high chloride content that might increase in the future. These days about 33% of Israeli citrus orchards are irrigated with this water, yet its potential effect on citrus orchards is not clear. Citrus is one of the major fruit crops of the world and is relatively salt-sensitive. Recently it was reported that continuous application of KNO3 might reduce chloride (Cl) uptake, and thus overcome the toxic effects of salinity. We examined the effect of KNO3 fertilization and rootstock on grapefruit's response to salinized SHAFDAN reclaimed water over four years. Trees were grafted on five different rootstocks and fertigated with two KNO3 regimes (118 vs. 148 mg 1-1 NO3), and exposed to...