José Francismar de Medeiros

Acúmulo de matéria seca e absorção de nutrientes pelo meloeiro "pele-de-sapo"

The melon produced in the state of Rio Grande do Norte is cultivated under irrigation and fertigation. With the use of fertigation and knowledge of the nutrients uptake curves it is possible to divide the total dose of nutrients in several applications during the crop cycle. Thus, the objectives of this study were to obtain curves of dry matter accumulation and the uptake of nitrogen, phophorus, potassium, calcium and magnesium for the pele-de-sapo melon plants and to determine the total uptake of these nutrients at the end of the crop cycle. The experimental design was an entirely randomized blocks with three replications. Plants were sampled at 22, 33, 43, 54 and 69 days after the sowing and were determined the dry matter and plant contents of N, P, K, Ca and Mg. It was observed that: 1) more than 50% of the extracted nutrients were accumulated in the vegetative part of the plant; 2) potassium, calcium and nitrogen are the nutrients more demanded by the melon plant; 3) the period of larger demand of nutrients happened between 43 and 54 days after sowing; 4) leaves and fruits are the principal drains of nutrients in the whole cycle of the crop.

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 e qualidade do melão sob lâminas de irrigação e cobertura do solo com filmes de polietileno de diferentes cores

O experimento foi conduzido de abril a julho de 2002, na Fazenda Santa Julia Agro-Comercial Exportadora de Frutos Tropicais Ltda, Mossoro, para avaliar o efeito da cobertura do solo com filmes de polietileno de diferentes cores (amarelo, marrom, preto, prateado e solo descoberto) e lâminas de irrigacao (100, 86 e 71% da lâmina padrao) sobre o rendimento e qualidade do melao Gold Mine cultivado na epoca chuvosa. O delineamento experimental utilizado foi o de blocos completos casualizados em esquema fatorial 5x3, com quatro repeticoes. Foram avaliados o numero e produtividade de frutos comerciaveis, refugos e totais, massa media de frutos comercializaveis, classificacao dos frutos, firmeza da polpa, espessura da polpa e teor de solidos soluveis. Houve interacao significativa entre os tipos de coberturas de solo e lâminas de irrigacao para a massa media de frutos comercializaveis, com os filmes de polietileno registrando os maiores valores em relacao ao solo descoberto. Os maiores rendimentos de frutos comercializaveis e totais, percentagens de frutos tipo exportacao, teores de solidos soluveis e espessura de polpa foram obtidos nas coberturas com filmes de polietileno. As lâminas de irrigacao nao afetaram de modo significativo a producao e qualidade dos frutos.

Crescimento de bananeiras sob diferentes níveis de salinidade da água de irrigação

The effects of different salinity levels of irrigation water (S1 = 0.55 dS/m, S2 = 1.70 dS/m, S3 = 2.85 dS/m e S4 = 4.00 dS/m) on vegetative growth in bananas Pacovan (AAB) and Marmelo (ABB) were evaluated. The experiment was carried out on a sandy clay loam Chromic Argisol in a split-plot scheme arranged in a randomized block design with four replications. The whole plots were composed of a row with 10-plants, five plants of each cultivar (subplot), and the data were collected from the three central ones. The irrigations were applied either dayly or every each two-days period in order to maintain a lixiviation fraction of 0.15, using approximate water sheets to keep the soil at field capacity. The data obtained at 110, 160, 220, 300, and 360 days after planting indicated that the water salinity level increase caused plant height, number of leaves, and leaf area to decrease significantly up to 240 days of the growth period, with the values becoming equalled after the rainy period.

Qualidade do fruto verde de coqueiro em função da irrigação com água salina

The effects of 4 levels of water salinity (0.1, 5.0, 10.0 and 15.0 dS m-1) obtained by addition of NaCl were studied on quality of 3.5 years old dwarf green coconut (Cocos nucifera L.). The experiment was carried out in a completly randomized block design in an initially non-saline sandy soil, using a micro sprinkler irrigation system in the municipality of Parnamirim-RN, Brazil, during the period of January 2000 to March 2001. The quality of fruit was evaluated by means of fruit weight, volume of water, obrix, and ionic composition of coconut water. The salinity of irrigation water reduced the mean weight and volume of fruit water but increased the ionic concentration expressed as electrical conductivity (EC) of coconut water and sugar content (obrix). The chloride and potassium ions were found to be present in higher proportions. After 11 months of irrigation with saline waters, the EC of saturation extract of soil, up to 0.80 m depth, increased in accordance with the salinity of irrigation water reaching values higher than 4 dS m-1 in treatments with EC of 10 and 15 dS m-1.

Germinação e crescimento inicial de híbridos de meloeiro em função da salinidade

Cultivation sites with intense evaporation rates, drainage deficit and inadequate use of fertilizers have increased the problems with salinity by impairing the good development of cultures. In melon plants, the high concentration of salts in both soil and water bring about morphological, structural and metabolic changes and inhibit their growth and development. Therefore, the aim of this work was to evaluate germination and initial growth stage of melon plants hybrids in different levels of salinity of irrigation water and submitted to a saline stress through imbibition. The treatments were organized in a completely randomized design in factorial scheme 2x3x5 (seeds treated with and without preimbibition in saline solution of NaCl (6 g/L), three hybrids of melon plant Hy Mark, Honey Dew Red Flesh and Daimiel, and five levels of electrical conductivity of irrigation water (0.45; 1.30; 2.15; 3.00 and 3.85 dS m-1), with three replicates. Evaluation of germination rate, emergency speed, foliar area, height and dry mass of the aerial part were made. The pre-germinant treatment of melon plant seeds with saline solution (6 g/L) provided larger dry mass of the aerial part of seedlings and a significant increase in the percentage of germination. On the other hand, the salinity of irrigation water reduced the foliar area, the dry mass of the aerial part and the height of the seedling. Compared to the other two cultivars, Daimiel proved to be the most tolerant to salinity due to higher estimates of the foliar area, dry mass of the aerial part and the height of the seedling.

Produtividade e qualidade de frutos de melão em resposta à cobertura do solo com plástico preto e ao preparo do solo

The effect of black polyethylene mulch and soil tillage intensity was determined on yield and quality of drip irrigated melon. The field trial was carried out in Mossoro, Brazil. The experimental design was randomized complete block in a factorial scheme with three replications. Two soil tillage methods were evaluated (strip tillage or tillage of the entire area) and tillage depth (20; 30; 40 and 50 cm), with split plots with or without mulch. Fruits were classified in export type, internal market type and rejected, to determine total yield and the yield of each type, number of fruits and fruit mean weight. Pulp firmness, total soluble solids, pulp thickness and fruit shape were determined. Results showed a decrease in pulp firmness with black plastic mulch. Strip tillage did not influence any studied characteristic. Yield of both export type and internal market melons was influenced by tillage depth. While deep tillage increased yield of export type melons, it reduced internal market yield.

Produtividade de frutos do meloeiro sob diferentes níveis de salinidade da água de irrigação, com e sem cobertura do solo

The number and the yield of fruits from two hybrid of muskmelon, submitted to different saline levels of irrigation water and soil covering was evaluated. A factorial outline was used 3 x 2 x 2 in a complete randomized blocks design with four replications. The factors were three levels of salinity of irrigation water, with electric conductivity of 1.2 dSm-1; 2.5 dSm-1 and 4.4 dSm-1 respectively, two hybrids, Gold Mine and Trusty, with and without soil covering using black-silvery double face polyethylene film. The hybrids reacted in different ways to the salinity of irrigation water. Reduction on the total number of fruits was observed only in the hybrid Trusty. The marketable yield of fruits was similar in both hybrids, being reduced with the increase of the electric conductivity. For the usage of soil covering the hybrids also reacted in a different way. The hybrid Trusty produced greater number of fruits and higher yield in treatments using soil covering.

Necessidade hídrica do meloeiro irrigado com água de diferentes salinidades e cultivado com ou sem cobertura do solo

The water requirement of the crops can be estimated from the reference evapotranspiration (ETo) and crop coefficients (kc). Aiming to estimate the water requirement of two cultivars of melon (Gold mine and Trusty) cultivated with and without soil covering with polyethylene film and irrigated by trickle irrigation with water of different salinities (1.2, 2.5 and 4.4 dS m-1), an experiment was installed in the municipal district of Mossoro, RN, in an Alfissol. To obtain the water requirement of the crop the water balance was accomplished in the plots, obtaining the crop coefficients. To obtain the variation in water storage in the soil profile and the subsurface flow three tensiometers were installed in each plot of two experimental blocks. The irrigation was estimated daily using ETo and kc recommended by FAO and was adjusted in agreement with the monitoring of the soil moisture. In water of higher salinity the evapotranspiration of the melon plant was reduced by 14%; the soil covering reduced it by 18%; and the cultivar Trusty evapotranspirated 11% less than the Gold mine. The water balance allow to estimate the crop coefficient of melon plants for different salinities, soil covering and cultivars.

Caracterização hidráulica do microaspersor Rondo, da Plastro

In order to assess the hydraulic characteristics of the microsprinkler Rondo 50 L h-1, with blue nozzle, manufactured by Plastro, tests were carried out in the Hydraulic Laboratory of the Escola Superior de Agricultura de Mossoro (ESAM). Estimates were made for discharge pressure head equation, manufacturerx92s coefficient of variation, profile of distribution, uniformity of water application and water application uniformity with overlap. The manufacturex92s coefficient of variation is classified as excellent and the characteristic equation is q = 3.4312 H0.516, characterizing a turbulent flow. The microsplinker has a throw radius of a 3.3 m. The best emitter spacing with overlap found was 1.2 x 1.2 m, although for spacing up to 3.6 x 3.6 m the application uniformity was above 80%.