Life cycle assessment of ecological footprint of water in wheat production under effect of irrigation regimes with application nano-silicon and nano-potassium chelate in Boushehr region

According to the previous studies, the basic solutions for solving the problem of water use of silicon and potassium fertilizers, which can be very useful for increasing the tolerance of plants to biotic and abiotic stresses. It has been reported in many studies that the use of silicon and potassium, due to mechanical resistance, translates the vertical position into leaves and stems, which in turn increases the light penetration into plant's canopy that the plant can do more photosynthesis. Therefore, this research was conducted with the aim of evaluating the ecological footprint life cycle of wheat production under the effect of irrigation regimes with the use of nano-silicon and nano-potassium chelate. The experiment was conducted as split plots based on a randomized complete blocks design with three replications at a research farm located in Boushehr during 2016-17. Irrigation regimes in four levels were: 1) irrigation interval 2 days (without stress), 2) irrigation interval 4 days, 3) irrigation interval 6 days, and 4) irrigation interval 8 days as main plots and nano-particle in three levels including nano-silicon, nano-potassium chelate and control (non-consumption) were considered as a sub-plots. Nano-silicon spraying with a concentration of 20 ppm was carried out at middle of tillage, the end of tillering and heading stages. Foliar application of nano-potassium chelate was used in middle of tillering and heading stages. The results of this study revealed that the irrigation interval delayed from two days to eight days leading to significantly decrease of the grain potassium percentage and grain protein content. The highest grain yield (3572 kg.ha-1) was obtained for irrigation intervals of two and four days with nano-potassium chelate consumption, which was due to spike length, number of grain per plant and number of grain per spike. Grain yields with nano-silicon application for irrigation intervals of two to four days were also ranked next. Delayed irrigation reduced the amount of water consumed by 7.35% from two days to eight days. The highest water use efficiency (2.12 kg.m3) was obtained for irrigation intervals of two days. In all four irrigation regimes, the highest water productivity (WP) was obtained with the use of nano-silicon and nano-potassium chelate utilization, which nano-potassium chelate had a more positive effect on WP. Carbon dioxide emission increased by two-day irrigation intervals about 5.47 percent compared to the eight-day irrigation interval, but the land occupation increased about 7.2 percent. With increasing irrigation intervals from two days to eight days, the impact categories of ecosystem quality, resource depletion, agricultural water scarcity, water depletion index (WDI) and water scarcity index (WSI) were decreased about 8.21, 8, 10.89, 9.29 and 9.91 percent. Furthermore, with the consumption of nano-silicon and nano-potassium chelate, the resource depletion, agricultural water depletion, WDI and WSI were lower than control treatment. The WDI about 7.28% and 8.24%, and about 9.7% and 8.57% was decreased with consumption of nano-silicon and nano-potassium chelate compared to control treatment. According to the findings, the best irrigation regimes in terms of improving quantitative and qualitative yield, increasing the water use efficiency and water productivity, as well as reducing the ecological footprints of water was intervals irrigation with two to four days, which were at a statistical level. In all the four irrigation regimes, the quantitative and qualitative yield of wheat increased with the use of nano-potassium chelate and nano-silicon, but the plant's water requirement decreased. Therefore, the consumption of nano-potassium chelate and nano-silicon resulted in increased water productivity, quantitative and qualitative yield and tolerance of wheat plant to water stress.