Hybrid Pigeonpea (ICPH 2740) Nodular Activity and Biological Nitrogen Fixation as Influenced by Agronomic Practices

Background: To explore the impact of agronomic practices on nodulation, nitrogenase activity and biological nitrogen fixation in hybrid pigeonpea, a field investigation was under taken at BW5 block ICRISAT development center (IDC), International Crops Research Institute for Semi-Arid Tropics (ICRISAT), Patancheru, Hyderabad, during kharif, 2021 and 2022. Methods: The seedlings were raised in portrays in advance to onset of monsoon during last week of May (28th May in 2021 kharif and 30th May in 2022 kharif) in both the years by filling portrays with cocopeat and vermicompost in 1:1 ratio. Transplanting of 24 days and 25 days old seedlings were done on 20th June in 2021 kharif and 23th June in 2022 kharif, respectively, on the same day of dibbling in the main field at 100 cm × 100 cm ,120 cm × 120 cm square geometry and 150 cm × 60 cm. Nutrient management treatments were imposed one week after sowing. Result: Among the planting methods higher nodule number and nitrogenase activity with transplanting compared to dibbling. 120 cm × 120 cm found higher nodule number plant-1 and nitrogenase activity but biological nitrogen fixation was higher with 100 cm × 100 cm ha-1 basis. With respect on nutrient management practices, control performed well in terms of higher nitrogenase activity and biological nitrogen fixation and on par with integrated approach of 100% soil test based NPK + vermicompost + PSB + seed treatment with Rhizobium. So, with transplanting method of establishment, 100 ´ 100 cm square plant geometry and 100% soil test based NPK + vermicompost + PSB + seed treatment with Rhizobium was recommended agronomic practices for hybrid pigeonpea.