Eficiência De Rizóbios Sob Doses De Fósforo Na Cultura Do Feijão-Caupi

Abstract

O uso da adubação nitrogenada vem caindo em desuso em detrimento de vários fatores um deles é a Fixação Biológica de Nitrogênio (FBN). O feijão-caupi é uma cultura que responde bem à inoculação com estirpes de rizóbio previamente selecionadas. Objetivou-se com esse trabalho avaliar a biomassa de cultivares de feijão caupi em função das bactérias fixadora de nitrogênio submetidas ou não as doses de fósforo. Foram conduzidos dois ensaios em casa de vegetação, sendo um com a cultivar de feijão-caupi BRS Nova Era e outro com cv BRS Sempre Verde, com quatro estirpes de rizóbio associadas ou não a seis doses de fósforo. O experimento foi composto por cinco repetições, disposto em esquema fatorial 5 x 6, sendo o primeiro fator correspondente à 4 estirpes de rizóbio: INPA 03-11B; R 48; BR 3277; BR 3299 mais um sem bactéria, o segundo fator à seis doses de adubo fosfatado: 0; 30; 60; 90; 120 e 150 kg ha-1 de P2O5. As características avaliadas foram: altura de planta, diâmetro de colo, massa seca da parte aérea, massa seca das raízes, número de nódulos e massa seca dos nódulos. As estirpes submetidas às doses de fósforo ou não proporcionaram acréscimo na altura de planta, diâmetro de colo, massa seca da parte aérea, massa seca da raiz para as duas cultivares. As estirpes que proporcionaram os melhores efeitos para as características de biomassa de modo geral foram: a INPA 03-11B, bem como, a estirpe BR 3299 para ambos cultivares a bactéria INPA 03-11B foi a que condicionou maior biomassa de modo geral. As doses de fósforo que apresentaram a máxima eficiência agronômica para as duas cultivares quando associadas as estirpes avaliadas variaram de 50 a 80 kg ha-1 de P2O5 para a maioria das variáveis estudadas nesse trabalho.

Bradyrhizobium japonicum AND PHOSPHORUS FERTILIZATION ON Vigna Unguilata (L.) WALP

“…Leaf phosphorus content (0.37 dag kg −1 ) increased by 61% compared to the mean value of 0.23 dag kg −1 of the control without inoculation and 68% compared to the inoculated control (0.22 dag kg −1 ) (Figure 2A). Silva et al (2019) observed that a dose of 90 kg ha −1 of P2O5 presented the best differentiation regarding the effect of strains, while 0 kg ha −1 of P2O5 had the lowest means for most strains, demonstrating the synergistic effect of phosphorus fertilization on the strains to increase the shoot dry mass. The highest estimated mean was conditioned by the strain INPA 03-11B, with a value of 1.75 g at a dose of 107 kg ha −1 of P2O5.…”

“…Thus, phosphorus fertilization has been studied with great emphasis because this nutrient participates in various physiological processes in plants and helps in the nodulation, consequently optimizing the process of biological nitrogen fixation (BNF) (Silva et al, 2019). Araújo (2019) evaluated the effects of inoculation with Bradyrhizobium sp.…”

Second-crop cowpea under residual phosphorus doses in the Brazilian Amazon

“…The low 1,000-grain weight may have occurred due to the low availability of P, reducing the grains weight (Fancelli & Dourado Neto 2007). Due to the short cycle between planting and harvesting, as well as the low volume of soil explored by the bean roots, the low availability of nutrients in the soil is one of the main factors limiting the yield of this crop (Silva et al 2019a). There is also the fact that P is demanded throughout the vegetative cycle, until the bean maturation, what allows the adequate functioning of the carbohydrate translocation mechanism, so that there is no reduction in yield (Grant et al 2001).…”

“…In Paragominas and other cities in the southeastern region of the Pará state, where the soybean and corn crops are expanding, Oxisols with medium to very clayey textures are predominant (IBGE 2008), which, although suitable for farming, are acidic and have low natural fertility, in which phosphorus (P) is one of the most limiting elements (Rodrigues et al 2003). On the other hand, cowpea has shown frequent responses to P (Smyth & Cravo 1990a) and the low availability of this element in the soil negatively affects the plant growth and, consequently, yield (Smyth & Cravo 1990b, Silva et al 2019a.…”

Dosage and timing of nitrogen fertilizer application on snap beans

“…The absence of N in the control treatment may have stimulated the biological fixation of atmospheric N by diazotrophic microorganisms native to the soil used in the experiment (SILVA et al, 2019), while the excess (60 kg ha -1 ) of N provided in the treatment impaired the action of these microorganisms, resulting in the low performance of this dose as compared to the control.…”