Increasing the productivity and water use efficiency of apple trees as affected by drip irrigation and mulching in new reclaimed soils

Two field experiments to study the effect of three irrigation rates of 13.584, 10.188 and 6.792 m. /tree/year (I1, I2 and I3) and two mulching types viz, black polethylene and dry cut grass, (M1, M2, MO) comparing to bare soil respectively as well as their interactions on production, fruit quality, water consumptive use (WCU), crop coefficient (Kc) and water use efficiency (WUE) of anna apple trees bedded on Malus rootstock and grown in loamy sand soil. Reduced drip irrigation regime from 13.584 to 6.792 m. /tree/year significantly decreased fruit yield associated with decreasing fruit set and increasing preharvest fruit drop, and also decreasing average fruit weight length, diameter, total soluble solids (TSS%), water consumptive use and crop coefficient (Kc) values. The highest values always belonged to 11 and 12 rates in both seasons. While, the highest values of fruit firmness, water use efficiency (WUE) kg/m. were obtained with the deficit (13) and moderate (12) irrigation regimes without significant difference between them. Meanwhile, total acidity was not affected by the tested irrigation regimes. Soil mulching with dry cut grass or black P.E produced maximum yield with good physical and chemical properties, it also decreased monthly and seasonal water consumptive use and Kc values but, increased water use efficiency (WUE). The interaction (I x M) was usually significant which obtained the highest productivity, best quality, highest water use efficiency and less water consumptive use values were recorded with (I2 x black P.E) and (I2 x cut grass) combination treatments in the two seasons of study. Thus, this study recommends Anna apple growers to use moderate irrigation rate I2 (10.188 m. /tree/year) under dry cut grass mulching in (I2x cut grass) combination treatment which considered the best one for obtaining maximum yield with a good quality. This treatment also reduced water consumptive use and increased water use efficiency (WUE).