Paulo Igor Barbosa e Silva

Efeitos da aplicação de doses de nitrogênio e densidades de plantio sobre os rendimentos de espigas verdes e de grãos de milho

The effect of nitrogen levels applications (0; 40; 80 and 120 kg N ha-1) and planting densities (30; 50 and 70 thousand plants ha-1) was evaluated over plant and ear heights, green ear yield (grains with 70-80% of humidity), grain yield and components of grain production of Centralmex maize cultivar. The experiment was set in a factorial scheme in randomized complete blocks with five replications and carried out under dryland conditions in Mossoro, Rio Grande do Norte, Brazil. Green ears yield was evaluated by number and weight of marketable ears with husk, and number and weight of marketable ears without husk. All evaluated traits increased with increasing nitrogen levels and decreasing planting densities, except 100 grains weight which was not affected by nitrogen levels. An effect of planting densities x nitrogen levels interaction was observed over number and weight of unhusked ears, number and weight of husked ears, and number of mature ears.

Parcelamento da adubação nitrogenada e rendimento de espigas verdes de milho

Avaliaram-se os efeitos da epoca da aplicacao de nitrogenio (120 kg N ha-1, como sulfato de amonio) e do parcelamento dessa aplicacao sobre o rendimento de espigas verdes de milho, em dois anos, em Mossoro, sob irrigacao por aspersao. Avaliaram-se o numero e peso total de espigas verdes empalhadas e o numero e peso de espigas comercializaveis, empalhadas e despalhadas. Utilizou-se o delineamento de blocos ao acaso com quatro repeticoes. Os tratamentos aplicados foram: aplicacao de todo o nitrogenio por ocasiao do plantio (1-0-0) ou em cobertura aos 25 (0-1-0) ou aos 45 (0-0-1) dias apos o plantio e aplicacao do fertilizante de forma parcelada (0-1/3-2/3, 1/3-0-2/3, 1/3-2/3-0, 0-1/2-1/2, 1/2-0-1/2, 1/2-1/2-0, 0-2/3-1/3, 2/3-0-1/3, 2/3-1/3-0 e 1/3-1/3-1/3). Os efeitos dos tratamentos foram independentes dos efeitos de anos. Os tratamentos (0-0-1) e (0-1/3-2/3) foram os que, em geral, proporcionaram os maiores rendimentos, mas outros tratamentos propiciaram rendimentos comparaveis, estatisticamente. Os piores rendimentos foram obtidos com o tratamento 1-0-0.

Efeitos de épocas de aplicação de nitrogênio no rendimento de grãos do milho

Um estudo foi realizado em dois anos, com irrigacao por aspersao, para avaliar os efeitos da epoca de aplicacao de 120 kg/ha de N (sulfato de amonio) no rendimento de graos do milho. Utilizou-se o delineamento de blocos ao acaso, com cinco repeticoes e os seguintes tratamentos: aplicacao de todo o N por ocasiao do plantio (1-0-0), em cobertura, aos 25 (0-1-0) e aos 45 (0-0-1) dias apos o plantio, e aplicacao do N de forma parcelada (0-1/3-2/3, 1/3-0-2/3, 1/3-2/3-0, 0-1/2-1/2, 1/2-0-1/2, 1/2-1/2-0, 0-2/3-1/3, 2/3-0-1/3, 2/3-1/3-0 e 1/3-1/3-1/3). O efeito de tratamentos foi independente do efeito de anos. O maior rendimento de graos (4.960 kg/ha) foi obtido com o tratamento 0-1/3-2/3, mas todos os demais tratamentos propiciaram rendimentos comparaveis, exceto os tratamentos 1-0-0, 1/3-2/3-0 e 2/3-1/3-0, que apresentaram os menores rendimentos.

Green ear yield and grain yield of maize after harvest of the first ear as baby corn

Baby corn (BC) consists of the corn ear harvested two or three days after silk emergence. BC is a profitable crop, making possible a diversification of production, aggregation of value and increased income. Removing the first female inflorescence induces corn to produce others, making possible to produce several BC ears or, alternatively, BC (by harvesting the first ear) and green ears or grain. The objective of this work was to evaluate green ear yield and grain yield, after harvesting the first ear as BC. Corn cultivar AG 1051 was submitted to the following treatments, in a random block design with ten replicates (52 plants per plot): BC harvesting; green ear harvesting (grain moisture content between 60 and 70%); mature ear harvesting; BC harvesting and harvesting of other ears as green or mature ears. Marketable green ears yield or grain yield produced without removing the first inflorescence were superior to the green ears yield or grain yield produced after removal of the first inflorescence harvested as baby corn. Harvesting only the first ear as baby corn, and then harvesting green ears or the mature ears, provided lower baby corn yields than that obtained by harvesting all ears as baby corn. Economically, the best net revenues would be obtained by exploring the crop for the production of green ears, green ears + baby corn, baby corn, baby corn + grain, and grain, in this order.

Produtividade do meloeiro em função de cutivares e épocas de semeadura

The region comprised by the municipalities of Mossoro-Acu is quite important with regard to yellow melon yield in the State of Rio Grande do Norte, where melon crops are grown from June to November. During this period, variations in climatic factors occur, suggesting the possibility of sowing season influences on the behavior of melon plants. The objective of this work was to evaluate the effects of sowing seasons (8/19, 9/9 and 9/29, 1999) and cultivars (Rochedo, FA 646, Gold Pride, Gold Mine, and Goldex) on melon plant productivity. A completely randomized blocks design with split-plots and three replicates was utilized. The seasons were considered as plots, and subplots consisted of cultivars. No effects of the interaction between sowing seasons × cultivars on the evaluated traits were observed. With regard to total number of fruits/ha (TNF), weight (kg/ha) total fruits, and number of marketable fruits, the best cultivars were, respectively, Rochedo and AF 646; Rochedo, AF 646 and Gold Pride; and, AF 646. The cultivars did not differ with regard to weight (kg/ha) of marketable fruits. The sowing season factor only influenced TNF. Seeding on 9/29 provided the best results.

Distribuição do teor de sólidos solúveis totais no melão

The total soluble solids content (TSSC) in different portions of the fruit of yellow melon (Cucumis melo L.) cultivars. Two experiments were carried out with cultivars (AF-646, Gold Mine, Gold Pride, Rochedo and Goldex), in two periods. In the first experiment, the TSSC was determined in the basal (near the peduncle), median and apical portions. In the second experiment, the TSSC was evaluated in the ventral (facing and touching soil), lateral, and dorsal portions. The experimental design was of randomized complete blocks in a splitplot scheme with three replications. The cultivars were assigned to plots and fruit fractions assigned to sub-plots. Three fruits of each plot were fractioned in the mentioned portions, peeled, and the pulp was homogenized in a blender, filtered in nylon and three readings in the digital refractometer were made. In the first experiment, there was only the effect of different portions. TSSC in basal portion (8.66oB) was lower than in the median (9.53oB) and in the apical (9.48oB) portion, which did not differ from each other. In the second experiment, there was the effect for cultivars (C) and portions (P), without interaction for C x P. The Goldex cultivar presented the highest TSSC (10.03oB) and the AF-646 the lowest (8.11oB). TSSC in ventral (8.94oB) and dorsal (9.07oB) portions did not differ from each other and was higher than in lateral fractions (8.69oB).

Tamanho ótimo da parcela para experimentação com girassol

The aim of this study was to determine a suitable plot size for field experiments with the sunflower. An experiment was carried out in a randomised complete block design with 14 sunflower cultivars and 10 replications. The plots consisted of four rows, six metres in length, spaced 0.7 m apart with 0.3 m between plants. The working area of the plot (7.56 m 2 ), consisting of the two central rows, was divided into 12 basic units, each consisting of three plants per row (0.63 m 2 ), from where the yield of the sunflower seeds was obtained. Suitable plot size was estimated using the intraclass correlation coefficient method. The detectable difference between treatments was also estimated (d). The optimum plot size for the evaluation of grain yield in the sunflower was 2.52 m 2 (working area), considering a boundary of one row on each side. Greater gains in experimental precision (16%) with increases in plot size, occurred up to eight basic units (5.04 m 2 ) using seven replications. Increasing the number of replications and the plot size was more efficient

Efeitos do substrato no enraizamento de estacas caulinares de Bougainvillea.

A Bougainvillea spectabilis Willd . e interessante, nas arborizacoes residencial e urbana, porque floresce durante todo o ano e apresenta variacao de cores de bracteas e tolerância a estresses hidricos. A percentagem de pegamento das estacas da buganvilia e, em geral, pequena e pode estar associada ao substrato usado. Oobjetivo do trabalho foi avaliar os efeitos do substrato sobre a percentagem de enraizamento de estacas de buganvilia. Dois experimentos foram realizados, num delineamento inteiramente casualizado, com dez repeticoes. No primeiro, os tratamentos foram: ‘areia vermelha’ (AV), ‘areia grossa’ (AG), AV + AG, AV + palha de carnaubeira Copernicia cerifera Mart.) curtida (PC), AG + PC e AV + AG + PC. A analise de uma amostra de AG indicou densidade aparente de 1,21 mg m-3, retencao de umidade de 8,00 (0,01 Mpa), 10,2 mm e 51,03 mm m-1 de agua disponivel e, em g kg-1: 904 de areia grossa, 85 de areia fina, 4 de silte e 7 de argila. Os valores respectivos para AV foram de 1,20 mg m-3, 10,96 (0,01 Mpa), 13,1 mm, 65,28 mm m-1 e 405, 556, 5 e 34 nas fracoes granulometricas. Maiores percentagens de estacas enraizadas foram obtidas com o uso de AG (24%) ou AG + AV (28%). No segundo experimento, PC foi substituida por humus de minhoca (HM). Maior percentagem de estacas enraizadas foi obtida com AG + HM (73%).