Nitrogen and dry matter accumulation in wheat plants inoculated with Azospirillum brasilense

Abstract

Aiming at assessing the effect of inoculation with two strains of Azospirillum brasilense, 245 and JA04, under the forms of powder and granulate inoculant on dry matter production, total N accumulation, and grain production of wheat plants of cultivar BR 23, a trial was carried out under field conditions. Inoculated treatments and inoculated treatments plus 15 kg N.ha^-1, absolute control, and 60 kg N.ha^-1 (15 kg N.ha^-1 at sowing and 45 kg N.ha^-1 at tillering) were distributed in blocks at random with four replications. Dry matter and total N accumulation, as well as grain production, were evaluated 20 days after anthesis and at maturity. Straw biomass variation between both evaluations was positive for all inoculated treatments, while such variation was negative in the non-inoculated treatments, indicating straw biomass accumulation instead of loss in the treatments with inoculation. Inoculation promoted a greater absorption of N at post-anthesis stage period, in which a higher availability of N did not contribute to an increase in grain production. Powder peat inoculant of strain JA04, plus 15 kg N.ha^-1 at sowing, replaced nitrogen fertilization of 45 kg N.ha^-1, applied as topdressing, without any negative effect on yield.