Effect of irrigation management with injection superabsorbent gel and organic matter on water use efficiency and quantitative and qualitative yield of orange (Thompson variety)

Optimal use of agricultural inputs, especially water, will result in sustainable agriculture and food security. Therefore, proper management of soil moisture and the use of new methods to maintain and increase soil moisture storage capacity are important. Thus, the aim of this research was investigation the effect of irrigation management with injection superabsorbent gel and organic matter on water use efficiency and quantitative and qualitative yield of orange. The experiment was carried out as split plot in randomized complete blocks design with three replications in Miyandoroud region, Mazandaran province in 2015 and 2016. Three irrigation management including 100, 75 and 50% of plant water requirement were chosen as main plots and two superabsorbent gel injection depth including 30 and 60 cm were chosen as sub plots and four organic matter level (superabsorbent gel, vermi-compost, combined of organic matter and superabsorbent gel and control treatment were chosen as sub sub plots. The results revealed that the most fruit weight and fruit volume were obtained for 100% of water requirement irrigation management with gel injection in 30 cm of soil depth. Moreover, the maximum fruit diameter, fruit volume and fruit weight was achieved for 100% of water requirement irrigation management with combined applied of organic matter and superabsorbent gel. According to findings of treatments interaction, there were observed the negative correlation between TSS percentage and fruit diameter, fruit volume and fruit weight. Based on triple interaction of treatments, with decrease of water usage based on water requirement the young branch length, leaf area, pH, growth density, WUE, tree yield and yield per hectare were statistically significantly decreased that the negative impact of that at gel injection in 60 cm of soil depth and control treatment was more than other treatments. The highest WUE (16.14 kg.m^-3) was obtained for 100% of water requirement irrigation management with gel injection in 30 cm of soil depth and combined applied of organic matter and superabsorbent gel. Moreover, the most tree yield was produced with 100% of water requirement irrigation management with gel injection in 30 cm of soil depth and consumption of superabsorbent gel, vermi-compost and combined applied of organic matter and superabsorbent gel. The maximum yield per hectare was achieved by 100% of water requirement irrigation management with gel injection in 30 cm of soil depth and consumption of vermi-compost and combined applied of organic matter and superabsorbent gel (44.03 and 46 ton per hectare, respectively). Therefore, combined applied of organic matter and superabsorbent gel can increase the moisture storage capacity by increasing the WUE and thus improving the quantitative and qualitative yield of orange.