Response of wheat to mineral nitrogen fertilizer and biofertilizer (Azotobacter sp. and Azospirillum sp.) inoculation under different levels of weed interference

Abstract

It is important to develop integrated fertilization strategies for crop production that enhance the competitive ability of the crop, minimize weed competition, and reduce the risk of nonpoint source pollution from nitrogen. In order to study the effects of mineral nitrogen fertilization and biofertilizer inoculation on grain yield, yield components and protein content of wheat (Triticum aestivum L.) under different levels of weed interference, a field experiment in Factorial scheme based on Randomized Complete Block design was conducted in three replications. Experimental factors were: (i) Four levels of chemical nitrogen fertilizer (0, 100, 150 and 200 kg N ha–1), (ii) Two levels of biofertilizer (with and without inoculation) containing Azotobacter sp. and Azospirillum sp. and (iii) Two levels of weed interference (weedy check and weed free). Wheat yield, yield components and protein content of grains had a strong association with the N fertilization, biofertilizer inoculation and weed interference. Higher rates of N fertilization and biofertilizer (Azotobacter  sp. and Azospirillum  sp.) inoculation increased plant height, spike number per unit of area, grains number per spike, 1 000-grains weight, grain yield, biological yield and grain protein content while weeds interference decreased significantly all these traits except plant height. Application of 150 kg N ha–1 was statistically in par with 200 kg N ha–1 in the most of the studied traits. Moreover, our results showed that manual hoeing prevents weeds from being a limiting factor for crop productivity in wheat. It seems that moderate N rate (about 150 kg N ha–1) can be beneficial to improve growth, development and total yield of inoculated wheat. Thus it is suggested to use a combination of organic and inorganic fertilizers to achieve the highest yield without negative effect on grain quality that will lead to environmental conservation.