No abstract

Propôs-se, neste trabalho, determinar o tamanho adequado de parcela para avaliação do rendimento de grãos do girassol, razão pela qual foi realizado, no período de maio a julho de 2011, um experimento no delineamento em blocos completos casualizados com 14 cultivares de girassol e 10 repetições. As parcelas foram constituídas de quatro fileiras com seis metros de comprimento espaçadas de 0,7 m e entre plantas de 0,3 m. A área útil da parcela, composta das duas fileiras centrais, foi dividida em 12 unidades básicas (UBs) cada uma de três plantas na fileira, medindo-se o rendimento de grãos do girassol por unidade básica. O rendimento de grãos das UBs adjacentes foi agrupado de modo a formar sete tipos de parcelas de cinco tamanhos diferentes pré-estabelecidos. O tamanho ótimo da parcela experimental foi estimado por meio do método da máxima curvatura modificado (3,74 m2) e do modelo linear segmentado com platô (2,48 m2) cujo tamanho de 3,74 m2 de área útil foi considerado adequado para avaliação do rendimento de grãos do girassol e menor que o tamanho geralmente usado nas pesquisas com o girassol.

Removal of the first female inflorescence in corn induces the plant to produce new inflorescences, which allows the first ear to be harvested as baby corn and the second to be harvested as green or mature ear (dry corn). The objective of this study was to compare the following production systems fertilized with nitrogen levels (0, 80, and 160 kg ha -1 ), applied to corn hybrid AG 1051: baby corn harvesting (BC); green ear harvesting (GC); mature ear harvesting (DC); and harvesting of the first female inflorescence as baby corn + harvesting the other ears as green corn (BC + GC) or as dry corn (BC + DC). A randomized complete block design with split-plots (nitrogen in plots) and nine replicates was used. The BC system provided higher baby corn yields than the BC + GC or the BC + DC systems. For all traits employed to evaluate green corn yield, the GC system provided higher yields than the BC + GC system. The BC + DC system provided lower grain yield than the DC system. The application of nitrogen provided increases in all traits evaluated, except for number of kernels ear -1 and 100-kernel weight. The revenue (total and additional total) and additional profit values, in descending order, were obtained with the BC, BC + GC, BC + DC, GC, and DC systems, for all nitrogen levels. The values for those measurements increased as nitrogen dose increased. At the dose of 80 kg N ha -1 , the highest profitability index (percentage of additional revenue that is converted into additional profit) was obtained from DC sales. However, with the application of the highest nitrogen rate, the highest profitability was obtained from BC sales.

RESUMO -Planting trees is an important way to promote the recovery of degraded areas in the Caatinga region. Experiments (E1, E2, and E3) were conducted in a randomized blocks design, with three, three, and five replicates, respectively. The objectives were to evaluate biomass of the shoots of: a) gliricidia (G) and sabiá (S), as a response to planting density; b) G, S, and neem (N) in competition; c) G, and S in agroforestry. E1 was conducted in split-plots, and planting densities (400, 600, 800, 1000, and 1200 plants ha -1 ) as subplots. E2 consisted of a factorial comprising the following plots: GGG, NGN, SGS, NNN, GNG, SNS, SSS, GSG, NSN (each letter represents a row of plants). E3 was conducted with G and S in agroforestry experiment. The trees were harvested after 54, 42, and 27 months old, in E1, E2 and E3, respectively. In E1, G presented higher green biomass of the stems and leaf at smaller densities than S, but lower green biomass of branches at most densities. The species did not differ for mean stem dry biomass and leaf dry biomass, but G showed higher branch dry biomass at most densities. Higher planting densities increased green and dry biomass of stems, branches, and leaves in S, but decreased those characteristics in G, with the exception of leaf dry mass, which was not influenced by density. In E2, the behavior of each species was identical in plots containing the same or different species. Griricidia showed the highest green biomass of stems and branches, and the highest values for geren biomass of the leaf were observed for gliricidia and neem. The highest stem, branch, and leaf dry biomass values were obtained for G, S, and N, respectively. In E3, G was superior for stem and leaf green biomass, and for stem and branch dry biomass. There were no differences between species for the other biomass values. Palavras-chave: Azadirachta indica; Gliricidia sepium; Mimosa caesalpiniifolia. BIOMASSAS DE ESPÉCIES ARBÓREAS EM RESPOSTA A DENSIDADES DE PLANTIO E À COMPETIÇÃO INTERESPECÍFICA ABSTRACT -Existe interesse na recuperação de áreas degradadas da Caatinga com o plantio de árvores. Experimentos (E1, E2 e E3) foram realizados, em blocos ao acaso com três, três e cinco repetições, respectivamente, para avaliar as biomassas da parte aérea: a) da gliricidia (G) e sabiá (S), em resposta à densidade de plantio; b) da G, S e nim (N) em competição; e c) da G e S em experimento agroflorestal. E1 foi realizado com

The four to five-fold price of onion hybrid seeds accounts for the wide use of open pollinated onion populations in Northeastern Brazil. Here we report the identification of maintainer and male-sterile onion lines within the 'Alfa São Francisco' yellow onion population, after three years of work, associating random field pairing of male-fertile plants with selected male-sterile plants and a PCR-based marker cytoplasm monitoring system. Male-sterile plants produced flowers with light green anthers which were easily detected in the field. A 2.0% frequency of male-sterile plants was estimated in the 'Alfa São Francisco' sampled population. Male-sterile plants produced the 5'cob-marker 180-bp and the orfA501-marker 473-bp fragments, suggesting the T-cytoplasm type, while the maintainer line produced only the 5'cobmarker 180-bp. Pairing 'A' line with a red onion resulted in 100% F1 red bulbs produced from harvested seed in the 'A line', confirming that a stable CMS system was identified within the Brazilian tropical 'Alfa São Francisco' population. Hybrids produced with another 'Baia periforme' onion population (Line 'C') and the 'A' identified lines' have resulted in a 38% bulb yield increase compared with the best parent, 'Alfa São Francisco'. The identified 'A' and 'B' lines, associated with other developed S1 and S2 populations ('C' lines) will be used to produced commercial hybrids well adapted to Brazilian low latitudes and with affordable prices for growers.