Agro-climatic indices of fodder maize, Zea mays L in relation to nutritional status

A field experiment was conducted during summer season of 2011 at the research farm of the Department of Agronomy, Punjab Agricultural University, Ludhiana to study the effect of farm yard manure (FYM) and nitrogen on the different agro-climatic indices of summer maize fodder. The experiment was laid out in split plot design with three levels of FYM in main plots and four levels of nitrogen in sub-plots. The different agro-climatic indices were GDD, photo-thermal units, helio-thermal units and phenol-thermal index were studied at 50 per cent tasseling, 50 per cent silking and harvest stage of maize fodder. Increasing level of either FYM or nitrogen lowered the GDD requirement over the lower level. Crop which received the highest quantity (25 tons) of FYM required the minimum number of PTU to attain 50 per cent flowering (15030), silking (17554) and harvest stage (19282). Crop which received the highest amount of either FYM or inorganic nitrogen required minimum number of helio-thermal units for attaining various phenophases. Pheno-thermal index gradually increased with the increase in fertility level either through or inorganic fertilizer for attaining silk and harvestable stage. Summer maize fodder with good nutritional status can utilize the thermal heat and radiation more efficiently.