Desempenho simbiótico e produtivo de cultivares de soja submetidas a co-inoculação com Azospirillum
Carregando...
Data
2019-02-28
Autores
Libório, Paloma Helena da Silva
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
A co-inoculação (Bradyrhizobium + Azospirillum brasilense), para a cultura da soja, apresenta-se como uma ferramenta para maximizar os benefícios obtidos com a fixação biológica de nitrogênio. A pesquisa desenvolve constantemente inoculantes, contendo estirpes elites de bactérias, no entanto, as características associadas aos parâmetros de fixação biológica de nitrogênio, não têm sido contempladas pelos programas de melhoramento genético de soja. Mediante o exposto, o presente estudo objetivou avaliar a capacidade simbiótica e desempenho produtivo de cultivares de soja submetidas a co-inoculação por meio de análises uni e multivariadas em dois anos agrícolas. As cultivares foram submetidas a co-inoculação no sulco de semeadura e controle (sem co-inoculação). O delineamento experimental utilizado foi em esquema de faixas com três repetições. No estádio reprodutivo R1, foram avaliados: índice de conteúdo de clorofila, altura da planta no florescimento e comprimento da raiz, massa seca da parte aérea e raiz, número de nódulos das raízes principal, secundárias e total, massa seca dos nódulos das raízes principal, secundárias e total e nitrogênio total na parte aérea. No estádio reprodutivo R8, foram avaliados: altura da planta na maturação, altura de inserção da primeira vagem, número de nós, número de ramos, número de vagens, número de grãos, massa de mil grãos, produtividade e teor de nitrogênio total nos grãos. Para as análises univariadas os dados foram submetidos a análise de variância e as médias comparadas pelo teste de Scott-Knott a 5%. Para as análises multivariadas, três abordagens exploratórias foram realizadas: componentes principais, análise de agrupamento e análise de fatores. No ano agrícola 2016/17, a co-inoculação proporcionou maior rendimento de grãos, o que correspondeu a um acréscimo de 20,78%. Pelas análises multivariadas as variáveis altura da planta no florescimento, massa seca da parte aérea, massa seca da raiz, massa seca de nódulos total, número de vagens e produtividade de grãos, foram as mais apropriadas para selecionar cultivares de soja com base em parâmetros de fixação biológica de nitrogênio e produtividade. A análise de componentes principais resultou em 3 componentes, os quais explicaram 73,51% da variância. A análise de agrupamento pelos métodos de Ward e k-médias permitiram a formação de quatro grupos. As cultivares BRS 7380 RR, DS 5916 IPRO, CZ 36B31 IPRO, BMX GARRA IPRO, BMX ÍCONE IPRO, TFC 6702 IPRO, CD 2720 IPRO, AS3680 IPRO, AS3730 IPRO, 5G 7315 IPRO e SYN 1560 IPRO apresentaram melhor relação simbiótica e produtiva. No ano agrícola 2017/18, a co-inoculação proporcionou novamente maior rendimento de grãos, o que correspondeu a um acréscimo de 16,87%. As cultivares ADV 4672 IPRO, GDM 16I024 IPRO, CZ36 B31 IPRO, NS6300 RR e 96Y90 RR foram as que apresentaram melhor relação simbiótica e desempenho produtivo. Pela análise de fatores, verificou-se que quatro processos conseguiram reter 60,20% da variância total e as variáveis que melhor caracterizaram a fixação biológica de nitrogênio e produtividade foram: massa seca de nódulos total, teor de nitrogênio na parte área e grãos, altura de inserção da primeira vagem e produtividade de grãos. Os resultados obtidos nos dois anos agrícolas enfatizam a existência de variabilidade genética a ser explorada pelos programas de melhoramento genético de soja, o que protagoniza o grande desafio para a melhoria da capacidade de fixação biológica de nitrogênio em soja.
Co-inoculation (Bradyrhizobium + Azospirillum brasilense), is presented as a tool to maximize the benefits obtained in the biological nitrogen fixation. Research is constantly developing inoculants containing elite strains of bacteria, however, the traits associated to the biological nitrogen fixation parameters have not been contemplated by the genetic improvement programs of soybean. The present study aimed to evaluate the symbiotic capacity and productive performance of soybean cultivars submitted to co-inoculation through of univariate and multivariate analyzes in two crop years. The cultivars were submitted to co-inoculation in the planting furrow and control (without co-inoculation). The experimental design used was a split-block with three replicates. In the reproductive stage R1, chlorophyll content index, plant height at flowering and root length, dry mass of shoot and root, number of main, secondary and total root nodules, dry mass of main root nodules, secondary and total, besides total nitrogen in the aerial part. At the R8 reproductive stage, plant height at maturity, height at first pod insertion, number of nodes, number of branches, number of pods, number of grains per plant, mass of one thousand grains, grain yield and total nitrogen in the grains. For the univariate analyzes the data were submitted to analysis of variance and the means compared with the Scott-Knott test (5%). In the multivariate analyzes, the three exploratory explorations were: the main components, the clustering analysis and the factor analysis. No agricultural year 2016/17, a combination that resulted in a higher yield of grains, which corresponded to an increase of 20.78%. From the multivariate analyzes, the variables: plant height at flowering, dry shoot mass, dry root mass, total nodule dry mass, number of pods and grain yield were the most appropriate to select soybean cultivars based on biological nitrogen fixation and productivity components. Principal component analysis resulted in 3 components, which accounted for 73.51% of the variance. The cluster analysis by the Ward and kmeans methods allowed for the formation of four groups. The cultivars BRS 7380 RR, DS 5916 IPRO, CZ 36B31 IPRO, BMX GARRA IPRO, BMX ÍCONE IPRO, TFC 6702 IPRO, CD 2720 IPRO, AS3680 IPRO, AS3730 IPRO, 5G 7315 IPRO e SYN 1560 IPRO, presented a better symbiotic relationship, showing synergism between cultivar and bacteria. In the agricultural year 2017/18, co-inoculation again provided higher yields of grains, which corresponded to an increase of 16.87%. The cultivars ADV 4672 IPRO, GDM 16I024 IPRO, CZ36 B31 IPRO, NS6300 RR e 96Y90 RR. presented a better symbiotic relationship and productive performance. By the analysis of factors, it was verified that four processes managed to retain 60.20% of the total variance and the variables that best characterized the biological fixation of nitrogen and productivity were: total nodule dry mass, area nitrogen content and grains, height of insertion of the first pod and yield of grains. The results obtained in the two crops years emphasize the existence of genetic variability to be explored by the genetic improvement programs of soybean, which is the main challenge for the improvement of the biological nitrogen fixation capacity in soybean.
Co-inoculation (Bradyrhizobium + Azospirillum brasilense), is presented as a tool to maximize the benefits obtained in the biological nitrogen fixation. Research is constantly developing inoculants containing elite strains of bacteria, however, the traits associated to the biological nitrogen fixation parameters have not been contemplated by the genetic improvement programs of soybean. The present study aimed to evaluate the symbiotic capacity and productive performance of soybean cultivars submitted to co-inoculation through of univariate and multivariate analyzes in two crop years. The cultivars were submitted to co-inoculation in the planting furrow and control (without co-inoculation). The experimental design used was a split-block with three replicates. In the reproductive stage R1, chlorophyll content index, plant height at flowering and root length, dry mass of shoot and root, number of main, secondary and total root nodules, dry mass of main root nodules, secondary and total, besides total nitrogen in the aerial part. At the R8 reproductive stage, plant height at maturity, height at first pod insertion, number of nodes, number of branches, number of pods, number of grains per plant, mass of one thousand grains, grain yield and total nitrogen in the grains. For the univariate analyzes the data were submitted to analysis of variance and the means compared with the Scott-Knott test (5%). In the multivariate analyzes, the three exploratory explorations were: the main components, the clustering analysis and the factor analysis. No agricultural year 2016/17, a combination that resulted in a higher yield of grains, which corresponded to an increase of 20.78%. From the multivariate analyzes, the variables: plant height at flowering, dry shoot mass, dry root mass, total nodule dry mass, number of pods and grain yield were the most appropriate to select soybean cultivars based on biological nitrogen fixation and productivity components. Principal component analysis resulted in 3 components, which accounted for 73.51% of the variance. The cluster analysis by the Ward and kmeans methods allowed for the formation of four groups. The cultivars BRS 7380 RR, DS 5916 IPRO, CZ 36B31 IPRO, BMX GARRA IPRO, BMX ÍCONE IPRO, TFC 6702 IPRO, CD 2720 IPRO, AS3680 IPRO, AS3730 IPRO, 5G 7315 IPRO e SYN 1560 IPRO, presented a better symbiotic relationship, showing synergism between cultivar and bacteria. In the agricultural year 2017/18, co-inoculation again provided higher yields of grains, which corresponded to an increase of 16.87%. The cultivars ADV 4672 IPRO, GDM 16I024 IPRO, CZ36 B31 IPRO, NS6300 RR e 96Y90 RR. presented a better symbiotic relationship and productive performance. By the analysis of factors, it was verified that four processes managed to retain 60.20% of the total variance and the variables that best characterized the biological fixation of nitrogen and productivity were: total nodule dry mass, area nitrogen content and grains, height of insertion of the first pod and yield of grains. The results obtained in the two crops years emphasize the existence of genetic variability to be explored by the genetic improvement programs of soybean, which is the main challenge for the improvement of the biological nitrogen fixation capacity in soybean.
Descrição
Palavras-chave
Bactérias diazotróficas, Fixação biológica de nitrogênio, Glycine max, Inoculação mista, Nodulação, Produtividade de grãos