Genetic divergence among maize hybrids by morphological descriptors

Two experiments with 25 maize commercial hybrids were carried out in a direct sowing system in Southern Brazil in the harvests of 2009/2010 and 2010/2011. Quantitative descriptors were used with the objective of determining the genetic divergence and the relative contributions of traits among hybrids for extraction of inbred lines. This study was carried out in Oxisol soil using a randomized block design with four replicates. Data were subjected to combined analysis of variance, and based on the multivariate analyses, Tocher and average linkage (UPGMA) cluster analyses, based on generalized distance of Mahalanobis, to quantify divergence in addition to Singh criterion to validate trait with the most contribution. The multivariate methods were consistent with each other, and the weight of 100 grains was the trait that contributed most to the divergence and had similar behavior in grain yield between hybrids in both years. Furthermore, this descriptor representing significant genetic variability for crossings and lines extraction to hybridization between BM 3061, ATL 200 and P 30B39 Y

Parâmetros genéticos entre caracteres quantitativos no girassol como critério de seleção para produtividade de aquênios

Two experiments were conducted in southern Brazil in no-tillage system, in order to estimate genetic parameters and the direct and indirect effects of components for achene yield as a selection criterion in sunflower. We analyzed eight sunflower hybrids at two locations, in a randomized complete block design with four replicates, determined through quantitative descriptors: insertion height of the head, and head stem diameter, weight of 1000 achenes, number of achenes per head, mass by achene head and yield achene. Estimates of genetic parameters were based on combined analysis, decomposing interactions in genetic and environmental components. Considering the coefficient of genetic variation, indirect effects of components and heritability, there are higher possibilities for responses to selection in sunflower achenes by descriptors mass and mass of achenes per head, with its indirect association interrelated pathways for the increase in the achenes of yield.Foram conduzidos dois experimentos no sul do Brasil em sistema de semeadura direta, com objetivo de estimar os parâmetros genéticos e os efeitos diretos e indiretos dos componentes para o rendimento de aquênios como critério de seleção no girassol. Foram avaliados oito híbridos de girassol em duas localidades, sob delineamento de blocos casualisados com quatro repetições, determinados por meio dos descritores quantitativos: altura de inserção do capítulo, diâmetro do caule e capítulo, massa de 1000 aquênios, número de aquênios por capítulo, massa de aquênios por capítulo e produtividade de aquênios. As estimativas dos parâmetros genéticos foram baseadas em análise conjunta, decompondo as interações em componentes genéticos e ambientais. Considerando o coeficiente de variação genético, efeitos indiretos dos componentes e herdabilidade, há maiores possibilidades de respostas à seleção no girassol pelos descritores massa de aquênios e massa de aquênios por capítulo, sendo suas vias de associação indireta interrelacionadas para o incremento no rendimento de aquênios

SUCESSÃO DE PLANTAS DE COBERTURA SOBRE OS COMPONENTES DE RENDIMENTO NO FEIJOEIRO

Objetivou-se com este trabalho avaliar as influências de diferentes plantas de cobertura  sobre as características agronômicas do feijão. O experimento foi conduzido em Latossolo Vermelho Aluminoférrico, utilizando delineamento de blocos casualisados, com quatro repetições, sendo os dados submetidos ao teste Tukey e comparados por meio de contrastes ortogonais. Os tratamentos consistiram das plantas de cobertura, procedendo seu cultivo em sistema solteiro, bem como alguns consórcios, através das espécies: Linhaça (Linum usitatissimum); Azevém (Lollium multiflorum); Aveia Preta e Branca (Avena stringosa e A. sativa); Ervilhaca (Vicia Sativa); Nabo Forrageiro (Raphanus sativus) e Triticale (Triticum secale). Os atributos agronômicos do feijão avaliados foram: massa de 1000 grãos e por legume, comprimento e número de legumes por planta e parcela, população de plantas e rendimento final. Verificou-se influência direta e distinta sobre os componentes de rendimento do feijão, tendo o número de legumes a maior relação com a produtividade do feijão. Dentre as plantas antecessoras utilizadas, a Ervilhaca e Nabo Forrageiro proporcionaram maior incremento produtivo, diferentemente do Azevém, assim como a Linhaça, que resultaram nos menores rendimentos do feijã

Sucessão de plantas de cobertura sobre os componentes de rendimento no feijoeiro

The objective of this study was to evaluate the influences of different plants covering on the agronomic characteristics of beans. The experiment was conducted on Red Latossol alumino-ferric, using randomized block design with four repetitions, being the data submitted to the Tukey test and compared by orthogonal contrasts. Treatments consisted of covering plants, carrying its growth in single system, as well as some consortia, across species: Flaxseed (Linum usitatissimum); Ryegrass (Lollium multiflorum), Black and White Oats (Avena Stringosa and A. sativa), vetch (Vicia sativa), wild radish (Raphanus sativus) and Triticale (Triticum secale). The agronomic attributes evaluated of bean were: the 1000 seeds per pod, length and number of pods per plant and plot, plant population and yield. Direct and different influence was verified on the components yield of beans, vegetables and the number of the larger relationship with productivity beans. Among the plants used predecessor, the Vetch and Turnip provided larger productive increment, differently of Ryegrass, as well as flaxseed, which resulted in lower yields beans.Objetivou-se com este trabalho avaliar as influências de diferentes plantas de cobertura sobre as características agronômicas do feijão. O experimento foi conduzido em Latossolo Vermelho Aluminoférrico, utilizando delineamento de blocos casualisados, com quatro repetições, sendo os dados submetidos ao teste Tukey e comparados por meio de contrastes ortogonais. Os tratamentos consistiram das plantas de cobertura, procedendo seu cultivo em sistema solteiro, bem como alguns consórcios, através das espécies: Linhaça (Linum usitatissimum); Azevém (Lollium multiflorum); Aveia Preta e Branca (Avena stringosa e A. sativa); Ervilhaca (Vicia Sativa); Nabo Forrageiro (Raphanus sativus) e Triticale (Triticum secale). Os atributos agronômicos do feijão avaliados foram: massa de 1000 grãos e por legume, comprimento e número de legumes por planta e parcela, população de plantas e rendimento final. Verificou-se influência direta e distinta sobre os componentes de rendimento do feijão, tendo o número de legumes a maior relação com a produtividade do feijão. Dentre as plantas antecessoras utilizadas, a Ervilhaca e Nabo Forrageiro proporcionaram maior incremento produtivo, diferentemente do Azevém, assim como a Linhaça, que resultaram nos menores rendimentos do feijão

Dissimilaridade genética e análise de trilha de cultivares de soja avaliada por meio de descritores quantitativos

In addition to the evaluations among genotypes, the use of multivariate techniques enables to restrict errors, mainly concerning genetic diversity, and therefore to predict combinations with greater heterotic effect, and the greater possibility of recovery of superior genotypes. The objective of this study was to evaluate the genetic divergence between 18 soybean cultivars based on six morphological characteristics. Path analysis was performed to verify the contribution of direct and indirect characters on grain yield. The Mahalanobis distance has founded techniques of both Tocher Method and dendrogram by Single Linkage. Five different groups were formed: with nine genotypes considered similar among them; while the cultivars CEP 59, Netuno and Urano formed groups isolated by the two grouping methods. The path analysis showed that the indirect characters had little influence on grain yield, with significant direct relationship with mass of 100 grain, and cultivars Tertulha and CEP 53 standing out with grain yields above 3.7 t.ha-1

Cover crop rotations in no-till system: short-term CO2 emissions and soybean yield

In addition to improving sustainability in cropping systems, the use of a spring and winter crop rotation system may be a viable option for mitigating soil CO2 emissions (ECO2). This study aimed to determine short-term ECO2 as affected by crop rotations and soil management over one soybean cycle in two no-till experiments, and to assess the soybean yields with the lowest ECO2. Two experiments were carried out in fall-winter as follows: i) triticale and sunflower were grown in Typic Rhodudalf (TR), and ii) ruzigrass, grain sorghum, and ruzigrass + grain sorghum were grown in Rhodic Hapludox (RH). In the spring, pearl millet, sunn hemp, and forage sorghum were grown in both experiments. In addition, in TR a fallow treatment was also applied in the spring. Soybean was grown every year in the summer, and ECO2 were recorded during the growing period. The average ECO2 was 0.58 and 0.84 g m2 h–1 with accumulated ECO2 of 5,268 and 7,813 kg ha–1 C-CO2 in TR and RH, respectively. Sunn hemp, when compared to pearl millet, resulted in lower ECO2 by up to 12 % and an increase in soybean yield of 9% in TR. In RH, under the winter crop Ruzigrazz+Sorghum, ECO2 were lower by 17%, although with the same soybean yield. Soil moisture and N content of crop residues are the main drivers of ECO2 and soil clay content seems to play an important role in ECO2 that is worthy of further studies. In conclusion, sunn hemp in crop rotation may be utilized to mitigate ECO2 and improve soybean yield