CHANGES INDUCED IN MAIZE LEAF GROWTH AND DEVELOPMENT BY ORGANIC AMENDMENTS AND N FERTILIZERS IN A CALCAREOUS USTOCHREPT SOIL, NORTHWESTERN INDIA

Temporal changes in leaf appearance, leaf area, and leaf longevity were recorded for two years from cowpea green manured (CGM), farmyard manured (FYM), and non-manured (control) plots of maize grown with 0, 75, and 125 kg N ha-1 as urea. Dependence of crop yield on leaf growth was evaluated. Organic amendments and nitrogen hastened the leaf appearance and increased leaf area and leaf longevity. Time required for appearance of the twelfth leaf under CGM was 88% of the time required under unmanured control. Leaf area index under CGM was between 1.28 and 3.25 times that in unmanured plots. Longevity of the seventh leaf under CGM was 1.66 times that in unmanured plots. Improvement in leaf growth and development with FYM was less than with CGM. There was more improvement in leaf growth and development with CGM than with 125 kg N ha-1 fertilizer. Maize grain yield was highly significantly correlated with leaf area index (r = 0.89) and leaf area duration (r = 0.87).