Maize is among the most important crops in the world. This plant species can be colonized by diazotrophic bacteria able to convert atmospheric N into ammonium under natural conditions. This study aimed to investigate the effect of inoculation of the diazotrophic bacterium Herbaspirillum seropedicae (ZAE94) and isolate new strains of plant growth-promoting bacteria in maize grown in Vitória da Conquista, Bahia, Brazil. The study was conducted in a greenhouse at the Experimental Area of the Universidade Estadual do Sudoeste da Bahia. Inoculation was performed with peat substrate, with and without inoculation containing strain ZAE94 of H. seropedicae and four rates of N, in the form of ammonium sulfate (0, 60, 100, and 140 kg ha -1 N). After 45 days, plant height, dry matter accumulation in shoots, percentage of N, and total N (NTotal) were evaluated. The bacteria were isolated from root and shoot fragments of the absolute control; the technique of the most probable number and identification of bacteria were used. The new isolates were physiologically characterized for production of indole acetic acid (IAA) and nitrogenase activity. We obtained 30 isolates from maize plants. Inoculation with strain ZAE94 promoted an increase of 14.3 % in shoot dry mass and of 44.3 % in NTotal when associated with the rate 60 kg ha -1 N. The strains N11 and N13 performed best with regard to IAA production and J06, J08, J10, and N15 stood out in acetylene reduction activity, demonstrating potential for inoculation of maize.
-The objective was to evaluate the growth of Arachis pintoi fertilized with nitrogen and water deficiency conditions. The study was developed in a 4 × 4 factorial arrangement with four nitrogen levels (0, 40, 80 and 120 kg N/ha) and four irrigation levels (25, 50, 75 and 100% of field capacity), in a completely randomized experimental design, with four replications. High doses of N benefited the production of root shoots while the root increased its production at a dose of 40 kg N/ha. The number of green and senescent leaves were influenced by N fertilization and the water regime, where higher doses of N provided greater total number of green leaves (364 leaves/pot) and the limitation of water resulted in a greater number of senescent leaves (78 leaves/pot). Observing the maximum point, the water regime of 90% of field capacity and 120 kg N/ha favored leaf appearance rate of 1.2 leaves/day and less phyllochron (4.6 days/leaf) at 85% of field capacity and 115 kg N/ha. The dose of 120 kg N/ha resulted in ultimate greater width (1.4 cm) and length (2.4 cm) of the leaf at 100% of field capacity. The final length of stolons showed quadratic effect for N, having greatest length (58.1 cm) at 75 kg N/ha and 100% of field capacity.
O objetivo deste trabalho foi selecionar em casa de vegetação bactérias que promovam o crescimento de plantas de eucalipto. O experimento foi realizado com o clone AEC 144 de Eucalyptus urophylla, no período de Junho a Agosto de 2016, com duração de 45 dias, tendo como tratamento 14 isolados bacterianos e 1 controle sem inoculação, com 4 repetições e perfazendo 60 parcelas, disposto em delineamento inteiramente casualizado. Foi avaliado a altura das plantas, diâmetro, índice de robustez das mudas e a contagem do número de folhas das plantas. Foi realizado o teste de Skot knott a 5% com as médias dos tratamentos. Os isolados bacterianos nativos de eucalipto UESBJNR32E, UESBJNR6E, UESBJNR5E, UESBJNR3E, UESBJMR6E, UESBJMR21E promovem o crescimento em plantas de eucalipto.
With the aim of isolating and inoculating diazotrophics bacteria, which is an efficient biological nitrogen fixation (BNF) in rice in Vitoria da Conquista-Ba, the present study was carried out in three steps. In the experiment of inoculation of diazotrophics bacteria, BRS Tropical and BRS MG Curinga, inoculation with the strain of bacterium ZAE 94, absence of inoculation and four doses of N (0, 20, 60 and 100 kg ha-1) were used. The control plants were used for the implementation of the isolation of bacteria efficient as the BNF. Final experiment was carried out with the three isolated strain, the ZAE 94, the absence of inoculation and the interaction with doses of N. Inoculation with strains of diazotrophic bacteria, guaranteed an increase in agronomic variables studied with positive effects on production and grain up to 208.5%.
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