José Espínola Sobrinho

Estimativa da área foliar do meloeiro

The leaf area of the Gold Mine melon was estimated when submitted to irrigation water levels varying from 55% to 130% of the hydric necessity of the crop, utilizing low and high salinity water. One plant per plot was collected at 19; 26; 34; 40 and 50 days after sowing, obtaining data of length, width, total leaf area, number of leaves, and individual leaf areas up to 24 leaves per plant. The results indicated that a partial correlation between the total plant leaf area (AF) and the number of leaves (NF) exists, with r2 = 0.95**, and the regression equation AF = 108NF - 516, with r2 = 0.95. The comparison of the models showed that at least one relation between leaf width (L) and leaf area (AF) differentiated from the others, even though the relation that assumes the whole data set (AF=0,826L1,89; r2 = 0.97) has a high determination coefficient.

Rendimento de melão amarelo cultivado em diferentes tipos de cobertura do solo e métodos de plantio

Avaliou-se o rendimento de melao amarelo em diferentes tipos de cobertura do solo e metodos de plantio, em experimento na Fazenda Agua Branca (FRUNORTE), no municipio de Carnaubais-RN. O delineamento experimental foi o de blocos casualizados, em esquema de parcelas subdivididas, com quatro repeticoes. As parcelas foram constituidas pelas coberturas do solo [palha de carnauba, filme de polietileno preto, filme de polietileno dupla face (prateado e preto) e solo descoberto] e as subparcelas pelos metodos de plantio (semeadura direta e transplante direto com producao de mudas em tubetes de 125 mL, copos plasticos de 180 mL e bandejas de 72 celulas). As caracteristicas avaliadas foram peso medio de frutos comerciaveis, numero de frutos comerciaveis, produtividade de frutos comerciaveis e nao comerciaveis e classificacao dos frutos. As coberturas do solo e os metodos de plantio nao apresentaram efeito significativo para numero, peso medio e produtividade de frutos comerciaveis e nao comerciaveis. Em relacao ao mercado externo, as coberturas do solo proporcionaram maior concentracao de frutos tipos 5 e 6, enquanto que para o mercado interno, registrou-se maior percentagem de frutos dos tipos 5 a 8.

Sombreamento para produção de mudas de alface em alta temperatura e ampla luminosidade

The growing of lettuce plants in tropical regions has been painful under high temperatures and ample luminosity, substantially affecting the crop cycle and yield. The effect of shading on lettuce seedlings production was evaluated in relation to three types of shading-net in four heights from the bed, under high temperature conditions and ample luminosity. An experiment was conducted in Mossoro, Rio Grande do Norte State, Brazil, in a completely randomized design in split-plot scheme, with three replications. The factor assigned to the plots was constituted by shading-net colors (white, green and black) plus a control (without net) and the other assigned to the subplots was constituted by net heights in the bed (20; 30; 40 and 50 cm above soil surface). Evaluations of plant height and diameter, number of leaves per plant, shoot fresh mass and plant growth rate were made on lettuce seedlings. There was a significant interaction between types of nets and their distances on leaf number per plant, shoot fresh mass and growth rate of lettuce seedlings. Seedlings grown under green net were significantly taller than those under white net. On the other hand, seedlings grown under green net were significantly larger than those under white and black net. Tallest and largest seedlings were obtained from lettuce cultivated under open sky. Highest quantity of shoot fresh mass and plant growing rate were obtained under white net shading at about 30 cm above soil surface.

Evapotranspiração e produção do melão Gália irrigado com água de diferentes salinidades e adubação nitrogenada

ABSTRACT This study aimed to determine the evapotranspiration and the yield of melon Galia irrigated with water ofdifferent salinity levels and nitrogen. Therefore, an experiment was carried out in Mossoro, RN,northeastern Brazil, in a completely randomized block design, with split-plots (5 x 3) and four replications.The treatments were the salinity levels S 1 = 0,65; S 2 = 1,65; S 3 = 2,83; S 4 = 3,06 e S 5 = 4,73 dS m -1 (assigned to the plots) and nitrogen: N 1 = 42,5; N 2 = 85,0 e N 3 = 127,5 kg ha -1 (applied throughfertigation to the subplots). The evapotranspiration of the crop was measured with weighing lysimeters,which occupied an area of 3,2 m 2 , located in two replications of S 1 and S 5 . The crop evapotranspirationdecreased in the range of the salinity levels S 1 to S 5 and totalized 204,5 and 172,4 mm, respectively.There were losses on marketable and total productivity, respectively, 12, 19 and 15% and 10, 16 and13% for nitrogen levels N 1 , N 2 and N 3 , per unit increase in salinity of irrigation water (EC

Necessidade hídrica da cultura do girassol irrigado na chapada do Apodi

Sunflower (Helianthus annuus L.) crop has been cultivated during the last years by the producers in Rio Grande do Norte, after the increase in demand due to National Program for Production and Use of Biodiesel. Being a non traditional crop in the region, there are no studies about the water management, so this work aimed to determine the crop evapotranspiration (ETc) and the crop coefficients (Kc) for the different development stages of the sunflower, cultivar Catissol I, in the plateau of Apodi - RN. Daily measurements of ETc were performed using two similar weighing lysimeters, with useful area of 2.7 m2.The reference evapotranspiration (ETo) was estimated using the method of Penman-Monteith FAO.The crop cycle was of 90 days and the total ETc and ETo during this period were, respectively, 442.0 and 580.6 mm.The phenological stages were defined with the duration of 28, 15, 27 and 20 days for the initial phase (Phase I), vegetative development (Phase II), flowering (Phase III) and physiological maturation (Phase IV), respectively.The crop coefficients obtained for the different stages of development were 0.52, 0.74, 0.98 and 0.81 for the phases I, II, III and IV, respectively.