Symbiotic Efficiency of Rhizobia Strains With Cowpea in Southern Maranhão

Abstract

-The objective of this study was to evaluate the symbiotic efficiency of three novel nitrogenfixing bacterial strains with cowpea cv. BRS Guariba as forage. Two experiments were carried out in the field in Balsas and São Raimundo das Mangabeiras, MA, in a randomized block design with seven treatments and four replications: three novel strains efficient in symbiotic nitrogen fixation with cowpea (UFLA 3-153, UFLA 3-154 and UFLA 3-164), two strains already approved as inoculants by MAPA (UFLA 3-84/SEMIA 6461 and INPA 3-11B/SEMIA 6462), and two controls without inoculation, with and without mineral N. Symbiotic efficiency of strains was determined by the number of nodules, nodules dry matter, shoot dry matter, relative efficiency, crude protein content and shoot N content. Strains UFLA 3-154 and UFLA 3-164 were the most efficient in Balsas, whereas UFLA 3-153 and UFLA 3-164 were the most efficient in São Raimundo das Mangabeiras. Strains UFLA 3-153, UFLA 3-154 and UFLA 3-164 were more efficient in symbiotic nitrogen fixation with cowpea than the strains already approved as inoculants UFLA 3-84 and INPA 3-11B in the climatic and edaphic conditions of southern Maranhão. UFLA 3-164 is the most efficient strain in this region.Keywords: Vigna unguiculata. Biological nitrogen fixation. Diazotrofic bacteria. Forage. EFICIÊNCIA SIMBIÓTICA DE ESTIRPES DE RIZÓBIO EM FEIJÃO-CAUPI NO SUL DO MARANHÃORESUMO -O objetivo deste trabalho foi avaliar a eficiência simbiótica de três novas estirpes de bactérias fixadoras de N2 em feijão-caupi cv. BRS Guariba como forrageira. Foram conduzidos dois experimentos em campo, em Balsas e São Raimundo das Mangabeiras, MA, em delineamento em blocos casualizados com sete tratamentos e quatro repetições, sendo: três novas estirpes eficientes em feijão-caupi (UFLA 3-153, UFLA 3-154 e UFLA 3-164), duas estirpes já aprovadas como inoculantes pelo MAPA (UFLA 3-84/SEMIA 6461 e INPA 3-11B/SEMIA 6462) e dois controles sem inoculação, com e sem N mineral. A eficiência simbiótica das estirpes foi determinada pelo número e massa seca de nódulos, produção de matéria seca da parte aérea, eficiência relativa, teor e acúmulo de proteína bruta e nitrogênio na parte aérea. As estirpes UFLA 03-154 e UFLA 3-164 destacaram-se na eficiência simbiótica de N 2 em Balsas e a UFLA 3-153 e UFLA 3-164 em São Raimundo das Mangabeiras. As estirpes UFLA 3-153, UFLA 3-154 e UFLA 3-164 são mais eficientes em fixar nitrogênio do que as estirpes aprovadas como inoculantes UFLA 3-84 e INPA 3-11B nas condições edafoclimáticas do sul do Maranhão. A UFLA 3-164 é a estirpe mais eficiente em fixar nitrogênio na região estudada.Palavras-chave: Vigna unguiculata. Fixação biológica de nitrogênio. Bactérias diazotróficas. Forragem.

Agronomic effectiveness of rhizobia strains on cowpea in two consecutive years

“…Gualter et al (2011) reported the efficiency of Rhizobia strains inoculated with cowpeas in the State of Maranhão, Brazil, and observed maximum yield (679 kg ha -1 ) for the treatments with effective strains such as INPA 03-11B. Farias et al (2016b) also evaluated the inoculation with rhizobia strains on cowpea in the state of Maranhão and Piaui and showed that UFLA 03-84 and INPA 03-11B strains had effectiveness of 61 and 69%, respectively, compared to the treatment with application of 80 kg ha -1 N. The strain UFLA 03-153 was superior to the strains (UFLA 03-84 and INPA 03-11B) and showed that in the Maranhão state the highest grain yield was obtained with the inoculated treatments. In the State of Piaui, inoculation with UFLA 03-84 and INPA 03-11B, was produced yield of 797 to 1,621 kg ha -1 in Dom Pedro: and 923 to 1,430 kg ha -1 in São Luís, respectively.…”

“…Recent studies show higher cowpea yield when inoculants or fertilizers are applied (Farias et al, 2016a, Farias et al, 2016b.…”

“…In recent years, the evaluation of effective rhizobia on various legumes have been increased and are conducted in the Brazilian Northeast with the promising results obtained for various legumes as described by Calheiros et al (2013Calheiros et al ( , 2015 for calopo; Lima et al (2012), for velvet beans, Torres Junior et al (2014) and Santos et al (2017) for peanuts, among others important species. However, few studies were carried out to evaluate the symbiotic effectiveness to increase cowpea yield by inoculation with specific strains of the Brazilian Northeast (Farias et al, 2016b).…”

Selection of elite Bradyrhizobium strains by biometric techniques for inoculation in cowpea

“…Specifically, for approval of atmospheric nitrogen (N 2 )-fixing bacteria for cowpea, Brazilian legislation considers strains (genotypes) of interest to be those whose viability and agronomic efficiency ensure yields higher than 500 kg ha −1 (República Federativa do Brasil, 2011). Although results confirm the benefits of native rhizobia communities in biological N fixation (BNF) for cowpea, the rhizobia community by itself established in the soil is not always sufficient to ensure a symbiosis that expressively contributes to increase the yield of this legume, and it is necessary to use inoculants containing strains that are more efficient in the BNF process (Costa, Nóbrega, Martins, Amaral, & Moreira, 2011Farias, Trochmann, Soares, & Moreira, 2016a, 2016bFerreira et al, 2019;Lacerda, Moreira, Andrade, & Soares, 2004;Martins et al, 2003;Moreira, 2006;Soares et al, 2006Soares et al, , 2014Zilli, Marson, Marson, Rumjanek, & Xavier, 2009).…”

“…Information regarding adaptability and phenotypic stability of these and of new strains to the most diverse environments should be considered essential due to the high heterogeneity of soils and climates in Brazil. This information would also optimize processes of approval of strains in the selection phase, such as UFLA 03-153 and UFLA 03-164, which have already shown promising results (Costa et al, 2011(Costa et al, , 2014Farias et al, 2016aFarias et al, , 2016bFerreira et al, 2013Ferreira et al, , 2019. Furthermore, it would stratify environments, characterizing them regarding the effects of each strain.…”