Frequency of irrigation and fertirrigation with nitrogen and phosphorus in the culture of watermelon

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoA melancieira (Citrullus lanatus (Thunb.) Matsum & Nakai), cucurbitÃcea cultivada em vÃrias partes do Brasil e do mundo, tem grande importÃncia socioeconÃmica para o Nordeste brasileiro. Nessa RegiÃo, o cultivo sob irrigaÃÃo vem crescendo e permitindo ao produtor ofertar frutos de melhor qualidade, no momento em que o preÃo à mais atrativo no mercado consumidor. Com o objetivo de avaliar a influÃncia de diferentes frequÃncias de irrigaÃÃo e fertirrigaÃÃo com nitrogÃnio e fÃsforo no desempenho produtivo da cultura da melancia, realizaram-se trÃs experimentos no sÃtio Paraguai, municÃpio de Cruz, CearÃ, no perÃodo de 12 de outubro a 20 de dezembro de 2010. O delineamento adotado foi o de blocos ao acaso com seis tratamentos e quatro repetiÃÃes. No experimento com irrigaÃÃo os tratamentos consistiram na aplicaÃÃo de diferentes frequÃncias de irrigaÃÃo, sendo: DM - diariamente (100% de manhÃ); DT - diariamente (100% de tarde); DMT - diariamente (50% de manhà e 50% de tarde); 2D - a cada dois dias; 3D - a cada trÃs dias e 4D - a cada quatro dias. Nos experimentos com diferentes frequÃncias de fertirrigaÃÃo nitrogenada e fosfatada, os tratamentos empregados foram: 2F - 2 fertirrigaÃÃes no ciclo; 4F - 4 fertirrigaÃÃes no ciclo; 8F - 8 fertirrigaÃÃes no ciclo; 16F - 16 fertirrigaÃÃes no ciclo; 32F - 32 fertirrigaÃÃes no ciclo e 64F - 64 fertirrigaÃÃes no ciclo. Avaliou-se a produtividade comercial (PC); massa (MF); diÃmetro polar (DP) e equatorial (DE); espessura da casca (EC) e teor de sÃlidos solÃveis (SS) dos frutos. Avaliou-se ainda a receita lÃquida para cada tratamento em todos os experimentos. Os tratamentos com frequÃncia de irrigaÃÃo influenciaram significativamente todas as variÃveis, sendo que a irrigaÃÃo diÃria (DMT - 50% de manhà e 50% de tarde) foi responsÃvel pela maior produtividade (69,79 t ha-1). Esse tratamento tambÃm foi responsÃvel pelo maior retorno econÃmico que foi de R$6.052,20. As diferentes frequÃncias de fertirrigaÃÃo com nitrogÃnio tambÃm influenciaram significativamente todas as variÃveis, com exceÃÃo da espessura da casca, a maior produtividade (80,69 t ha-1) foi obtida com o tratamento 64F - 64 fertirrigaÃÃes no ciclo, assim como a maior receita lÃquida (R$ 8,799,00). As distintas frequÃncias de fertirrigaÃÃo com fÃsforo influenciaram significativamente as variÃveis: produtividade comercial e espessura da casca, sendo que a maior produtividade (67,54 t ha-1) tambÃm foi obtida com o tratamento 64F - 64 fertirrigaÃÃes no ciclo. No entanto, a maior receita lÃquida (R 3.427,41) foi obtida para o tratamento 32F - 32 fertirrigaÃÃes no ciclo.The watermelon (Citrullus lanatus (Thunb.) Matsum & Nakai), cucurbit grown in various parts of the world, has great socioeconomic importance for the Brazilian Northeast. In this region, the irrigated watermelon cultivation has been increasing, allowing the producer to offer high quality fruits, right when prices are most attractive at the consumer market. Aiming to evaluate the influence of different frequencies of irrigation and (nitrogen and phosphorus) fertigation on watermelon crop growth performance, three experiments were performed on the Paraguai farm, at the Cruz municipality, state of CearÃ, in the period from October 12th, 2010 to December 20th, 2010. The statistical design was that of randomized blocks with six treatments and four replications. The treatments, in the irrigation experiment, consisted of applying different irrigation frequencies, being: DM (daily, 100% in the morning); DT (daily, 100% in the afternoon); DMT (daily, 50% in the morning and 50% in the afternoon); 2D ( irrigation once every two days); 3D (irrigation once every three days); 4D (irrigation once every four days). The treatments, in experiments with different frequencies of nitrogen and phosphorus fertigation, were: 2F (2 fertigations per cycle); 4F (4 fertigations per cycle); 8F (8 fertigations per cycle); 16F (16 fertigations per cycle); 32F (32 fertigations per cycle) and 64F (64 fertigations per cycle). We evaluated the commercial yield (PC), mass (MF), polar diameter (DP), equatorial diameter (DE), shell thickness (EC) and soluble solids (SS) of the fruit. We also evaluated the net revenue for each treatment in all experiments. The irrigation frequency treatments significantly influenced all variables, with the DMT irrigation (daily, 50% in the morning and 50% in the afternoon) accounting for the highest yield (69.79 t ha-1). This treatment also had the highest economic return, with R 6,052.20. The different nitrogen fertigation frequencies also significantly influenced all variables except the shell thickness, the highest yield (80.69 t ha-1) being obtained with 64F (64 fertigations per cycle), as well as the highest net revenue (R$8,799,00). The different phosphorus fertigation frequencies also significantly influenced the commercial yield and shell thickness variables, with the highest yield (67.54 t ha-1) being obtained with 64F (64 fertigations per cycle) treatment. However, the highest net revenue (R$ 3,427.41) was obtained for the 32F (32 fertigations per cycle) treatment

IRRIGATION FREQUENCY ON ECONOMIC PERFORMANCE AND PRODUCTIVITY OF TOMATO IN THE COAST OF CEARÁ, BRAZIL

The objective of this work was to technically and economically evaluate the productivity of tomato grown under different irrigation frequencies in the coast of Ceará, Brazil. The experiment was conducted in the experimental area of the Federal University of Ceará, Fortaleza, State of Ceará, Brazil, from August to December of 2011 and 2012. A randomized block experimental design was used in the two crop cycles, with six irrigation frequencies, consisted of 2 (F2), 3 (F3), 4 (F4), 5 (F5), 6 (F6) and 7 (F7) days of interval between irrigations, and four replications. The treatments were evaluated at twenty days after transplanting (DAT), when the plants were fully acclimated to the field. The harvesting began at seventy DAT and ended at ninety DAT. The variables analyzed were fruit length, diameter and weight, number of fruits per plant and fruit yield. The economic performance of the crop was also evaluated. Tomato producers of the coastal region of the State of Ceará, who aim to increase economic return, i.e., net income, must adopt a two- day irrigation frequency (F2)

Growth, gas exchange and yield of peanut in frequency of irrigation

This study was conducted to evaluate the effect of different irrigation frequencies on growth, gas exchange and yield of the peanut (Arachis ypogea L). The experiment was conducted in the field using the experimental design of randomized blocks with five treatments, five replications with four plants per plot. The treatments were composed: F2 = (irrigation every 2 days), F4 = (irrigation every 4 days), F6 = (irrigation every 6 days), F8 = (irrigation every 2 days) and F10 = (irrigation every 10 days). At 60 days after sowing (DAS), the gas exchange variables (photosynthesis, stomatal conductance and transpiration) and growth variables (plant height, leaf number, stem diameter and shoot dry matter) were evaluated. The highest irrigation frequency tested (every two days) promoted the best results for plant growth (leaf number, plant height, shoot dry matter) e for leaf gas exchange. The highest yield of field grown peanuts at the conditions prevailing in Fortaleza, Ceará, is associated with the adoption of an irrigation frequency interval of two days