The effect of combined use of nitrogen fertilizer with sugarcane residue compost and growth promoting bacteria on wheat cv. ‘Chmaran 2’ grain yield under terminal heat stress conditions in Ahwaz

In order to improve soil fertility, increase the capacity to hold water and nutrients in the soil, as well as improve the growth and yield of plants, the use of different organic fertilizers in the soil has great importance due to the problem of lack of organic matter in most soils of Iran. However, organic fertilizers alone are not able to meet the needs of plants and are not sufficiently available to farmers. On the other hand, the high consumption of chemical fertilizers causes environmental pollution and increases production costs. Therefore, in order to efficiently and effectively use organic and chemical fertilizers and achieve sustainable agriculture, combined use of organic and chemical fertilizers is recommended. Considering the effect of heat stress at the end of the season on the reduction of wheat production in Khuzestan, as well as the effect of reducing the use of chemical fertilizers and increasing the use of organic and biological fertilizers on the health of agricultural ecosystems, this experiment aims to investigate the effect of combined use of nitrogen chemical fertilizer with sugarcane residue compost and the application of growth promoting bacteria (PGPR) in late season heat conditions on the growth and yield of wheat were designed and implemented. This research was carried out in order to investigate the response of Chamran 2 wheat yield and yield components to combined use of nitrogen chemical fertilizer with sugarcane residue compost and growth promoting bacteria under the effect of late season heat stress. The experiment was carried out in the form of split-split plots in the form of a basic design of randomized complete blocks with three replications in the crop year of 2021-2022 in the research farm of Agricultural Sciences and Natural Resources University of Khuzestan. The experimental factors include three planting dates on December 1, December 20 and December 10 in the main plots; Six levels of combined use of nitrogen chemical fertilizer (urea) with organic fertilizer, sugarcane residue compost, including control (without chemical and organic fertilizer), 100% chemical fertilizer, 75% chemical fertilizer+ 25% organic fertilizer, 50% chemical fertilizer+ 50% organic fertilizer, 25% chemical fertilizer+ 75% organic fertilizer and 100% organic fertilizer in sub-plots and two levels of application and non-application of growth promoting bacteria (PGPR) in sub-plots. Each sub-plot was 3 meters long and 2 meters wide (with an area of 6 square meters) and included 10 crop lines at a distance of 20 cm from each other. The distance between the main and sub plots was half a meter and the distance between the blocks was considered to be two meters. After harvest maturity, the plants were harvested and the desired traits were measured. Analysis of variance showed that the effect of sowing date and the combined use of chemical fertilizer with organic fertilizer of sugarcane residue compost were significant on all measured traits. Also, the effect of plant growth promoting rhizobacteria was significant on all the measured traits except harvest index. Mean comparison showed that the highest grain yield (5663 kg/ha) was in the sowing date of 1 December and the use of 50% chemical fertilizer+ 50% organic fertilizer and the lowest grain yield (1155 kg/ha) was in the planting date of 10 December and no use of chemical and organic fertilizers. In general, the delay in planting and the occurrence of heat stress at the end of the season caused a decrease in grain yield, but in different planting dates, the combined use of 50% chemical fertilizer+ 50% organic fertilizer increased wheat grain yield.