Field evaluation of different levels of nitrogen and growth promoting bacteria on yield and yield components of cotton in delayed cultivation

Nitrogen (N) is the most important element limiting crop production in cotton cultivation. As N deficiency in plant decreases the seedcotton yield, excessive N availability negatively affects crop production, too. Therefore, N fertilizer management is very important in cotton cropping. Azotobacter and Azospirillum bacteria have been given much attention in agriculture due to non-symbiotic N fixation and improve plant growth and crop production. In order to the studying effect of N and Azotobacter and Azospirillum bacteria on yield and yield components of late-planted cotton cv. Golestan, a field experiment was conducted with four levels of N fertilizer (0, 30, 60 and 90 kg ha-1m from urea as the N source) and four treatments of cotton seed inoculation with the two PGPR bacteria (no inoculation, Azotobacter, Azospirillum and a equal combination of Azotobacter and Azospirillum bacteria). Basis on the results, the effect of N fertilizer was significant on yield and yield components of cotton, whereas the response of yield and yield components of cotton to seed inoculation was not significant. An insignificant interaction effect between the nitrogen and seed inoculation with bacteria was occurred on yield and yield components of cotton, too. According to the experiment's finding, in soil conditions like as present experiment, 75 kg N ha-1 is recommended for double-cropping cotton cv. Golestan, with expected seedcotton yield which is less than 2 tons per hectare.