The development of cultivars with an improved nitrogen use efficiency (NUE) together with the application of plant growth-promoting bacteria is considered one of the main strategies for reduction of fertilizers use. In this sense, this study: i) evaluated the effect of Azospirillum brasilense on the initial development of maize genotypes; ii) investigated the influence of A . brasilense inoculation on NUE under nitrogen deficit; and iii) sought for more NUE genotypes with higher responsiveness to A . brasilense inoculation. Twenty-seven maize genotypes were evaluated in three independent experiments. The first evaluated the initial development of maize genotypes with and without A . brasilense (strain Ab-V5) inoculation of seeds on germination paper in a growth chamber. The second and third experiments were carried out in a greenhouse using Leonard pots and pots with substrate, respectively, and the genotypes were evaluated at high nitrogen, low nitrogen and low nitrogen plus A . brasilense Ab-V5 inoculation. The inoculation of seeds with A . brasilense Ab-V5 intensified plant growth, improved biochemical traits and raised NUE under nitrogen deficit. The inoculation of seeds with A . brasilense can be considered an economically viable and environmentally sustainable strategy for maize cultivation.

ResumoA obtenção de cultivares de soja mais produtivas esta cada vez mais difícil, devido aos altos níveis de produtividade já alcançados para esta leguminosa. O trabalho teve como objetivo avaliar os componentes da produção de cultivares de soja de crescimento determinado e indeterminado, visando a seleção indireta para maior produtividade de grãos. Três cultivares de soja com tipo de crescimento determinado e quatro com tipo indeterminado foram avaliadas, no ano agrícola de 2009/2010. O delineamento experimental empregado foi blocos casualizados, com quatro repetições e sete tratamentos (cultivares). As características analisadas foram: altura da planta; número de nós por planta; número de vagens e grãos por planta; produtividade de grãos por planta; componentes da produtividade de grãos nos quatro últimos nós; massa de mil grãos; massa seca da planta; índice de colheita; número de ramos e vagens nos ramos. Empregou-se análise de variância em blocos ao acaso com informação dentro de parcela. As diferenças entre médias foram comparadas pelo teste de Tukey a 5% de probabilidade. As variâncias e covariâncias fenotípicas obtidas pela ANAVA geraram a matriz de correlações fenotípicas entre caracteres. Em seguida foi realizou-se a análise de trilha. Cultivares com tipo de crescimento determinado e indeterminado não diferem quanto aos componentes de produção, diferem apenas para altura na maturidade. Porém, os critérios usados para seleção não devem ser os mesmos entre os dois tipos de cultivares. O número de vagens totais e o número de vagens nos ramos para cultivares com crescimento determinado e o índice de colheita para os indeterminados mostraram maior importância para seleção indireta de cultivares mais produtivos. Independente do tipo de crescimento, o número de grãos por planta está diretamente relacionado com a máxima produtividade em soja. Palvras-chave: Glycine max, análise de trilha, genética, melhoramento AbstractThe obtain more productive soybean cultivars is increasingly difficult, due to high levels of productivity has already achieved for this legume. The work had as objective to evaluate the components of the production of soybean cultivars of determinate and indeterminate growth, aiming the indirect selection for major productivity of grains. Three cultivars of soybean with type determinate of growth and four with type indeterminate were evaluated, in the agricultural year 2009/2010. The experimental design was randomized blocks with four replications and seven treatments (cultivars). The characteristics analyzed were: plant height, number of nodes per plant, number of pods and grains per plant, grain yield

Water deficit is the major abiotic factor that limits crop productivity. Climate changes are likely to exacerbate drought stresses in the future. In the present work, we investigated the feasibility of using the Normalized Difference Vegetation Index (NDVI) combined with the canopy temperature and other physiological characteristics, such as chlorophyll content and gas exchange, to monitor soybean (Glycine max L. Merrill) plants differing in their drought response under glasshouse conditions. Additionally, the drought responses of the cultivars Embrapa 48 and BR 16 were assessed under conditions of natural drought, water deficit simulated by sheltering the plants from rain at the vegetative and reproductive periods and irrigation at field conditions. Remote sensing techniques could be used to initially assess the drought responses of soybean plants under controlled conditions. Additionally, we observed the relationship between the NDVI and several physiological characteristics, such as chlorophyll content, photosynthesis, stomatal conductance and transpiration. Therefore, the combination between remote sensing techniques and the assessment of physiological traits of plant materials at the same developmental stage and leaf areas is useful to accurately monitor cultivars presenting different drought responses.

In the final steps of a breeding program, it is necessary to evaluate several traits, which makes it difficult to select the superior genotypes. This study aimed to compare nonlinear indexes in the selection of superior soybean inbred lines obtained by recurrent selection. The experiment was carried out in Londrina, Paraná State, Brazil. During the 2010/11 and 2011/12 seasons, 67 soybean inbred lines and two commercial controls (BMX Potência RR and NK 7059 RR) were evaluated. The experimental design was a randomized complete block with three replicates. The evaluated traits were: days to maturity, agronomic value, lodging, first pod insertion height, and grain yield. A combined analysis of variance for seasons was performed and the sum of ranks index, ideotype distance index, and cultivars selection index were applied. All traits were significant for the genotypic source of variation and showed complex genotype × environment interactions. The selection indexes were consistent with each other. The ideotype and cultivar selection index showed higher concordance on indication of 15 superior inbred lines with a coefficient of coincidence of 80%. The inbred lines SR-03, SR-12, SR-22, SR-41, SR-49, SR-55, SR-61, and SR-62 were indicated for all indexes and are therefore considered superior to other inbred lines.

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