Demand of micronutrients for sweet pepper plants cultivated in a protected atmosphere

Abstract

Developed in a protected cultivation experiment evaluated the effects of nitrogen as urea and of potassium as potassium chloride on the concentration and micronutrient content for sweet pepper. Culture was constantly irrigated and developed in dark red latisol for 34 weeks. The production of fruits was continuous, with a total of 16 crops during the period. N increased the growth of the sweet pepper plants and decreased Fe, Mn, Cu and B levels in leaves and stems, besides decreasing Fe and Mn levels in the fruits, mainly up to dose 26.6g m^-2. Nevertheless, concentration of B and Cu in the fruits increased in a significant way at harvest time, after 11.5 weeks of planting. Increase of potassium doses resulted in a smaller growth of the sweet pepper plants and in higher levels of Fe and Mn in the stems and leaves, Cu in the stem and B in the fruits. After 34 weeks of growth, pepper leaves and stems concentrated more Fe, Mn and Cu, while B was more concentrated in the leaves and fruits. Highest level of B was present in the fruits, 101.7% and 64.6% respectively, at harvest time, after 11.5 and 31.5 weeks after the planting of sweet pepper. Mean concentrations of micronutrientes (mg kg^-1) in stem, leaf and fruits of sweet pepper were respectively: Fe=169.7; 243.9; 126.4; Cu = 4.0; 3.3; 2.2; Mn=186; 323; 44.2; B=0.12; 38.9; 32.3. Sweet pepper plants accumulated higher amounts of Fe and B and lower amounts of Mn and Cu. Fruits had the highest extracted proportion during 34 weeks. Contents of micronutrientes in the plant and the export by the sweet pepper fruits were (mg m^-2) B=225.3 (98%); Fe = 927.3 (92%); Cu=15.8 (91%); Mn=84.6 (78%);Cu=15.8 (91%);