Produção, trocas gasosas e estado nutricional da melancia, submetida a diferentes lâminas de irrigação e doses de boro.

Abstract

Boron, among micronutrients, is one that appears most often deficient in the soil, mainly due to the low availability of land and lack of knowledge of application and crop response to their application. As to the low availability in the soil, this condition is aggravated when the water shortage, since the mechanism involved in the contact with the root of boron is the mass flow that is directly proportional to the hydraulic conductivity. Regarding response to nutrient culture, it is believed that the optimal range between toxic and is very narrow. Therefore the objective of this study was to evaluate the effect of increasing doses of boron in watermelon crop irrigated with different irrigation in the municipality of Pentecost - CE. The statistical design was randomized block split plot with four replications. The plots were assessed four irrigation levels, 50%, 75%, 100% and 125% of potential evapotranspiration of the crop (ETpc) and subplots five levels, corresponding to 0.5, 1.5, 2.5, 3, 5, 4.5 kg ha-1 to B, taking with boric acid source. The boron contents in watermelon leaf tissue showed linear fit as a function of increasing doses and decreased linearly as a function of irrigation levels, ranging from 102.39 to 168.20 mg kg-1 and negatively correlated with productivity, indicating toxicity. Foliar N, P, K, Ca, Mg, Mn, Fe and Zn were not affected by irrigation and boron levels. Since sulfur and copper, influenced by irrigation and B levels, respectively. It was demonstrated effect of boron on the increased production of MSPA. The stomatal conductance, internal CO2 concentration and photosynthesis were not affected by factors, demonstrating that the blades did not impose on plants water scarcity, and that with the variables analyzed was impossible to pinpoint the influence of boron gas exchange. The crop transpiration was significantly affected by irrigation.