Thermal Requirement, Heat and Radiation Use Efficiency of Kharif Soybean in Middle Gujarat Region as Influenced by Cultivars and Plant Geometry

The present study proposes to measure the thermal requirements, heat and radiation use efficiency of kharif soybean cultivars (NRC 37, GS 1 and GS 2) in the central region of Gujarat. The findings of study conclude that among all the different geometry 30 x 10 cm produced highest seed (4403 kg/ha) and total biomass yield (5818 kg/ha) over the other two spacing because higher heat use efficiency (heat use efficiency (HUE) for Growing degree day (GDD)- 0.69 kg/ha/°C Day; HUE for Heliothermal units (HTU) - 0.14 kg/ha/°C Day hour; HUE for Photothermal units (PTU) - 0.05 kg/ha/°C Day hour). The cultivar NRC 37 (4415 kg/ha) produced highest seed yield followed by GS 1 (3799 kg/ha) and GS 2 (3670 kg/ha). Heat unit requirement of cultivar NRC 37 (GDD - 1952°C Day; HTU – 9894°C Day hour; PTU-25974°C day hour) was more as compared to GS 2 (GDD - 1951°C day; HTU – 9893°C day hour; PTU-25973°C day hour) and GS 1 (GDD - 1931°C day; HTU – 9809°C day hour; PTU-25681°C day hour), respectively. The radiation use efficiency (RUE) for seed yield and biomass are more in 45 x 5 cm geometry.