ABSTRACT Phenotypic plasticity is the ability of plants to undergo changes in morphology and yield components to adapt themselves to distinct environmental conditions. The knowledge on the changes in yield components of branches and stems at varied plant spatial arrangements needs to be updated due to recent changes in soybean production system. Thus, this study aimed to evaluate the yield components of branches and stems, as well as to assess the share of these plant parts in the total grain yield of soybean cultivars with indeterminate growth type, under different spatial arrangements. The experiment was conducted during the growing seasons of 2013/2014 and 2014/2015, under a randomized complete-block design and in a4 × 3 × 2 factorial scheme with three replications. Treatments consisted of four row spacing patterns (narrow rows, twin rows, traditional row spacing, and crossed rows), three seeding rates (150, 300, and 450 thousand viable seeds∙ha–1), and two cultivars (BMX Potência RR and BRS 359 RR). Narrow rows reduce pods and grains production in branches in relation to the traditional row spacing. The number of grains per pod of stem and of branches is not altered by the changes in plant arrangement. The increase in seeding rate reduces the number of pods per plant of branches in greater magnitude than that of stems. The rise in seeding rate results in larger thousand-grain mass both of branches and of stems, but varies with the growing season.

Resumo: O objetivo deste trabalho foi avaliar como variáveis relacionadas a ramos e hastes contribuem para a produção de grãos em plantas individuais de soja (Glycine max), cultivada a diferentes densidades de plantio, em uma cultivar moderna com tipo de crescimento indeterminado. Um experimento de campo foi realizado nas safras 2013/2014 e 2014/2015, em delineamento de blocos ao acaso, com 12 repetições, tendo-se utilizado a cultivar NK7059 RR, a quatro densidades de plantio: 135, 235, 315 e 440 mil plantas por hectare. A produção de grãos por planta foi avaliada e representou a plasticidade fenotípica, enquanto o número de ramos por planta, a percentagem da produção de grãos oriunda dos ramos e os componentes de rendimento oriundos dos ramos e das hastes, separadamente, foram considerados como variáveis independentes. O número de vagens por planta nos ramos foi a variável mais determinante da plasticidade da soja. Além disso, o número de vagens por planta nas hastes, o número de ramos por planta e a percentagem da produção de grãos oriunda dos ramos também estiveram associados à plasticidade. De forma contrastante, o número de grãos por vagem e a massa de mil grãos nos ramos e nas hastes contribuíram pouco para a plasticidade da soja 'NK7059 RR'.

Abstract: The objective of this work was to evaluate how branch and stem variables contribute to grain yield in individual soybean (Glycine max) plants, cultivated at different planting densities, in a modern cultivar with indeterminate growth type. A field experiment was carried out during the 2013/2014 and 2014/2015 crop seasons, in a randomized complete block design with 12 replicates, using the cultivar NK7059 RR at four planting densities: 135, 235, 315, and 440 thousand plants per hectare. Grain yield per plant was evaluated and represented phenotypic plasticity, while the number of branches per plant, percentage of grain production in branches, and separate yield components from branches and stems were considered as the independent variables. The number of pods in branches per plant was found to be the most important variable for soybean plasticity. In addition, the number of pods per plant on stems, number of branches per plant, and the percentage of grain production in branches were also associated with plasticity. Contrastingly, the number of grains per pod and the mass of a thousand grains in the branches and stems contributed little to plasticity in 'NK7059 RR' soybean.

RESUMO A alface é cultivada em todas as regiões brasileiras, porém há restrições ao seu cultivo em virtude de sua sensibilidade às condições adversas de temperatura, umidade do ar e disponibilidade de água. Diante disto, objetivou-se, com este experimento, avaliar a produção de quatro cultivares de alface americana, sob dois sistemas de cultivo. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema de parcelas subdivididas. As parcelas foram constituídas por dois sistemas de cultivo (túnel baixo de polietileno e campo aberto), e, as subparcelas por quatro cultivares de alface americana (Angelina, Rubette, Grandes Lagos 659 e Tainá), com quatro repetições. As características avaliadas foram: altura de plantas, diâmetro total da planta, diâmetro transversal da cabeça, comprimento de caule, diâmetro de caule, massa de matéria fresca de caule, número de folhas comerciais e não comerciais, massa de matéria fresca comercial e não comercial. Foi realizada análise de variância e as médias foram comparadas pelo teste de Tukey. O túnel baixo favorece o crescimento e a produção de cultivares de alface americana, em relação ao campo aberto. O cultivar Rubette mostra crescimento e produção superiores aos demais cultivares avaliados, nos dois sistemas de cultivo.

ABSTRACT The lettuce is grown in all regions of Brazil, however, there are restrictions on its cultivation, due to its sensitivity to the adverse conditions of temperature, humidity and water availability. In this context, the aim of this study was to evaluate the production of four lettuce cultivars under two cropping systems. The experimental design was randomized blocks in a split-plot scheme. The plots consisted of two cropping systems (low polyethylene tunnel and open field), and the sub plots of four lettuce cultivars (Angelina, Rubette, Grandes Lagos 659 and Tainá) with four replications. The characteristics evaluated were: plant height, overall diameter of the plant, transverse head diameter, stem length, stem diameter, stem fresh weight, number of commercial and non-commercial leaves, commercial and non-commercial fresh weight. Analysis of variance was performed and means were compared by Tukey test. The low tunnel favors the growth and production of lettuce cultivars in relation to open field. Cultivar Rubette shows growth and production superior to the other cultivars in both cropping systems.

ABSTRACT There are few studies on the interaction between soybean plant density and nitrogen fertilization. This research aimed to assess the effect of mineral nitrogen associated to different plant densities on yield, yield components and oil and protein concentrations of soybean grains. Two experiments were conducted in the 2013/2014 and 2014/2015 growing seasons, with randomized complete block design, in a split plots scheme, with six replications. Four sowing densities (150, 300, 440 and 560 thousand viable seeds∙ha–1) were allocated in the plots, and two nitrogen levels (0 and 45 kg N∙ha–1, applied at V2, using ammonium sulfate) were allocated in the subplots. There was no interaction between soybean plant density and the application of mineral nitrogen on yield, yield components and oil and protein concentrations in soybean grains. Higher plant population reduced the number of pods per plant and the contribution of branch sinks to the grain yield, but the effects on yield differed among the growing seasons. The mineral nitrogen fertilization did not increase yield and protein and oil concentrations in the grains, thus it was unnecessary.