Estudos sobre a nutrição mineral do sorgo granífero: V. efeitos das deficiências de micronutrientes (nota)

Grain sorghum var. TEY-101 was grown in nutrient solution in the presence and in the absence of micronutrients. Symptoms of deficieny of all micronutrients were obtained. Growth, as measured by dry matter production was affected by the treatments in the folowing decreasing, order: minus Fe, minus Zn, minus Mn, minus B, minus Mo and minus Cu. An additional treatment in which excess Mn was used revealed a relative tolerance of the variety to high levels of this element. The results of chemical analyses of the leaves suggest that the following contents (in ppm) of micronutrients are associated with the respective deficiencies: B - 20 to 40, Cu - 8 to 10, Fe - 198, Mn - 32 to 35, Mo - 0.5, Zn - 46 to 52; in the case of Fe the Fe/Mn relationship seems to give a better indication of the nutritional status than the content of the element per se, being igual to 1.7 in the healthy plants, and 0.6 in the iron deficient ones.O sorgo granífero, var. TEY 101, foi cultivado em solução nutritiva na presença e ausência de micronutrientes. Foram obtidos sintomas de carência e foi feita a determinação dos teores desses elementos nas folhas