Propagation Methods and Mulching Modulate the Quantum Yield, Ionic Relations, and Production Components of Sour Passion Fruit under Salt Stress

In semiarid regions of Brazil, water and/or soil salinity is one of the limiting factors for sour passion fruit production. Low rainfall rates combined with edaphic conditions (high concentrations of soluble salts) intensify deleterious effects on plants. Thus, strategies that minimize the effects of salt stress, e.g., grafting with tolerant species and soil mulching, are extremely important to ensure the expansion of irrigated fruit farming in this region. From this perspective, this study aimed to evaluate the effect of grafting and mulching on the quantum yield, ionic relations, and fruit production of sour passion fruit irrigated with moderately saline water. The experiment was conducted under field conditions in split plots, in a 2 x (2 x 2) factorial arrangement to evaluate the combination of low and moderate salinity water (main plot) with the propagation method (seeds and grafting on P. cincinnata) and without and with plastic mulching (subplots), with four replications and three plants per plot. The ionic relations in passion fruit leaves were increased with the use of rootstocks and plastic mulching under irrigation with moderately saline water. The use of mulching increased the yield of photosystem II in sour passion fruit. The passion fruit plants propagated by seeds had 187.52% more fruits than those grafted onto P. cincinnata. The use of rootstocks with P. cincinnata in sour passion fruit restricted the uptake of Na and Cl but reduced fruit production.