Beneficial effect of secondary treated wastewater irrigation on nectarine tree physiology

Abstract

Irrigation with secondary treated wastewater (STW) as a support to traditional irrigation management is becoming a necessary alternative to addressing issues of water shortage and fertilizer saving. The application of STW on young potted plants of Prunus persica (L.); cv: Big Top, grafted on GF 677, was studied outdoors on two consecutive seasons, during which three different irrigation treatments were compared: 1) irrigation with STW; 2) irrigation with tap water with the addition of mineral fertilizer (TW + MF) and 3) irrigation with tap water (TW). To assess the effects of the different irrigation treatments, tree nutritional status, shoot growth, Stem Cross Sectional Area (SCSA), Trunk Cross Sectional Area (TCSA), leaf gas exchanges, plant water status, fruit growth, fruit yield and quality were monitored during both seasons. Tree nutritional status, vegetative growth, TCSA, cumulative plant photosynthesis, fruit growth and yield were positively influenced by STW irrigation, compared to TW. TW + MF trees showed the highest vegetative growth and vegetative/reproductive ratio. This induced a rise in their water use and a consequent decrease in stem water potential, indicating the onset of water stress conditions. Results indicated that there was no negative effect of STW application on any of the monitored parameters. STW partially improved the plant physiological, nutritional and productive performances due to its intrinsic fertilizing effect. These results encourage further studies on the possibilities to directly use STW as an alternative source for irrigating and fertigating fruit crops even in open field conditions.