T. BALA SRIKANTH*, D. SAIDA NAIK, S. NARENDER REDDY AND B. BALAJI NAIK

Department of Crop Physiology, College of Agriculture, PJTSAU, Rajendranagar, Hyderabad-500 030.

ABSTRACT

The present research was carried out with the objective of studying the effect of irrigation regimes, nitrogen rates and their functional relationship on morpho-physiological, biochemical parameters and yield attributes in maize at Agricultural Research Institute, PJTSAU, Rajendranagar, Hyderabad. The maize seed variety of Cargill-900 is taken for investigation with main treatment as irrigation regimes at 60% DASM (I₁) (Depletion of available soil moisture), 40% DASM (I₂) and 20% DASM (I₃) and sub treatments as nitrogen rates at 90 kg N ha-1 (N₁), 180 kg N ha-1 (N₂) and 240 kg N ha-1 (N₃). The data was recorded on Physiological parameters like canopy temperature (T_leaf-T_air) (oc) and SPAD chlorophyll meter readings. Among the irrigation regimes highest chlorophyll meter readings and lowest canopy temperature (T_leaf-T_air) was recorded at 20% DASM (I₃) and the decreasing trend of chlorophyll meter readings and increasing trend of canopy temperature (T_leaf-T_air) was recorded with increasing the Depletion of available soil moisture (i.e. from 20% DASM (I₃) to 40% DASM (I₂) and finally to 60% DASM (I₁),which has recorded lowest chlorophyll meter readings and highest canopy temperature (T_leaf-T_air)). Among the nitrogen rates highest chlorophyll meter readings and lowest canopy temperature (T_leaf-T_air) was recorded at 240 kg N ha-1 (N₃) and the decreasing trend of chlorophyll meter readings and increasing trend of canopy temperature (T_leaf-T_air)was recorded with decreasing the nitrogen rates (i.e. from 240 kg N ha-1 (N₃) to 180 kg N ha-1 (N₂) and finally to 90 kg N ha-1 (N₁),which has recorded lowest chlorophyll meter readings and highest canopy temperature (T_leaf-T_air)). Among the interaction of irrigation regimes and nitrogen rates the treatment combination of 20% DASM in conjunction with 240 kg N ha-1 (I₃N₃) recorded significantly highest chlorophyll meter readings and lowest canopy temperature (T_leaf-T_air) compared to all other treatment combinations but remained on par with treatment combination of 20% DASM in conjunction with 180 kg N ha-1 (I₃N₂) of canopy temperature, treatment combination of 40% DASM in conjunction with 240 kg N ha-1 (I₂N₃) of chlorophyll meter readings and the lowest chlorophyll meter readings and highest canopy temperature (T_leaf-T_air) was recorded at treatment combination of 60% DASM in conjunction with 240 kg N ha-1 (I₁N₃). Data pertaining to before and after irrigation was found that the chlorophyll meter readings decreased after irrigation when compared to before irrigation. At 60% DASM (I₁) irrigation regime the chlorophyll meter readings decreased comparatively more than 40% DASM (I₂) and the negligible amount of decrease in chlorophyll meter readings is found in 20% DASM (I₃) after irrigation..

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