Estudos sobre a nutrição mineral do feijão macassar (Viana sinensis (L.) ENDL.). III: efeitos das carências de micronutrientes no crescimento, produção e composição mineral das folhas

Portugués. Foram induzidas deficiências de micronutrientes em duas cultivares de Vigna sinensis, "Dorminhoco" e "Pitiúba" cultivadas em solução nutritiva. A determinação de matéria seca das diferentes partes permitiu verificar o efeito de falta de cada elemento no crescimento e na produção. As análises minerais das folhas deram dados que servem para a avaliação do estado nutricional.

Inglés. Vigna sinensis, varieties "Dorminhoco" and "Pitiúba" were grown in nutrient solution both in the presence and in the absence of micronutrients dry matter production was measured either at the end of life cycle or whenever symptoms of deficiency were sufficiently acute to warrant an early harvesting; leaves were then analysed for mineral composition. Dry matter production obeyed the following decreasing order: Complete > - Mn = - Mo = - Cu > - Zn > - B; pods were formed and filled in all treatments except the last two; yield, however, was much lower than in the full strength solution which gave an average equivalent to 1.5 ton per hectare of dry beans. Leaf analyses showed consistently that lack of a nutrient in the substrate leads to a decrease in its contents in the tissue. Other variations were induced in leaf composition by the different treatments being all of them in agreement with common cases of dilution and interionic effects on uptake and in translocation. The inverse relationship between Fe and Mn, however was not substantiated. Tentatively the following leaf levels (in ppm) could be considered as satisfactory: B = 203 ± 31; Cu = 6±0.79; Fe = 817 ± 103; Mn = 148 ± 21; Mo = 0.24 ± 0.05; Zn = 43 ±9; deficient levels could be considered: B = 44 ± 25;Cu=5±1.2; Fe = 337 ± 31; Mn = 24 ± 6; Mo = 0.20 ± 0.08; Zn = 24 ± 5.