Use of SPAD-502 in the evaluation of chlorophyll contents and nutritional status of herbaceous cotton to nitrogen, sulphur, iron and manganese

Abstract

The application of indirect meter of chlorophyll SPAD-502 has been studied for several cultures and with satisfactory results in evaluation of the nutritional state of nitrogen. This work aimed at evaluating the employment of SPAD-502 in the leaf content analysis of chlorophyll, N, S, Fe and Mn in herbaceous cotton under greenhouse conditions. Four experiments were installed to study doses of N (1.5, 7.5, 15 and 22.5 mM L^-1), S (0.2, 1, 2 and 3 mM L^-1), Fe (10, 50, 100 and 150 µmol L^-1) and Mn (10, 50, 100 and 150 µmol L^-1), equivalent in all cases to 0.1, 0.5, 1.0 and 1.5 times the normal concentration of the solution Hoagland & Arnon, respectively. The SPAD index had a better correlation with chlorophyll a than with clorophyll b. The SPAD indexes were positively correlated to N leaf content and negatively correlated to S. Leaf contents of Fe and Mn did not correlate to SPAD index.