Investigation the effect of bentonite sulfur and nitrogen levels on root growth and physiological characteristics and yield of wheat (Triticum aestivum L.)

Consumption of appropriate amounts of nitrogen and sulfur together due to increased solubility of nutrients and nitrogen uptake increase wheat yield. Accordingly, a potted experiment was conducted using factorial method in a completely randomized design with four levels of urea fertilizer 0, 60, 120 and 180 kilogram per hectare of pure nitrogen with four levels of bentonite sulfur 0, 200, 400 and 600 kilogram per hectare on wheat of Sirvan cultivar and a field experiment with the same treatments in the form of a statistical design of randomized complete blocks using split plots with three replications in the research farm of Razi University of Agriculture and Natural Resources, Razi University of Kermanshah in 2016-2017 cropping year. In the pot experiment, the effects of interaction between nitrogen and sulfur as well as the effect of sulfur on the investigated traits in the roots were not significant. Conversely, the effect of nitrogen on most traits including total length, dry weight, density and root area was significant at 5 percent probability level. The highest values ​​of these traits in pots were 5554 centimeters, 6.24 gram, 0.44 centimeters per qubic centimeters of soil and 1676 square centimeters with 120 kilogram per hectare of nitrogen fertilizer, respectively. The results of field experiments did not show the effect of interaction between treatments on yield traits, yield components and pigments, but the simple effect of nitrogen and sulfur on most yield traits and yield components was significant. Nitrogen consumption increased biomass yield, grain yield, number of grains per square meter and number of spikes. With 60 kilogram per hectare nitrogen application compared to the control increased by 30.6, 31.9, 19.8 and 20.0 percent, respectively, but there was no significant difference between nitrogen levels of 60, 120 and 180 kilograms per hectare. With the consumption of 200 kilograms per hectare of sulfur, grain yield increased by 8.8 percent. In general, the results showed that the yield of wheat of Sirvan irrigated cultivar with 60 of kilograms per hectare nitrogen and 200 kilograms per hectare of sulfur had the highest agricultural and economic yields.