Yield, grain quality and soil microbial activity as influenced by phosphorus management in rice (Oryza sativa L.) under acidic Alfisols

Field experiment was carried out during 2018 and 2019 in a rice-green gram cropping system to study the effect of phosphorus (P) management in kharif rice under acidic Alfisols of Odisha, India. The experiment was conducted in split-plot design with three replications. Four main plots viz., P1-100% of soil test dose (STD) for P as basal to rice, P2- 100% of STD for P to both the crops, P3-50 % of STD for P to rice and 100% of STD for P to green gram, P4 -100% of STD for P to both the crops applied to green gram were allotted to the main plots and three rice varieties viz., V1-Mandakini, V2-Lalat and V3- Pratikhya were considered in the sub plots. Application of 100% STD for P to both the crops (P2) resulted in the highest grain and straw yield (3981 and 4715 kg ha-1, respectively). Rice variety Pratikshya maturing in 145 days produced the highest grain and straw yields of 3808 and 4399 kg ha-1, respectively. The grain quality parameters of rice like protein content (6.75 %), amylose content (20.36 %) and alkali value (4.60) were found highest in P2 which was significantly different from other P management practices. Rice variety Pratikshya produced a better quality grain like protein (6.63 %), amylose (20.28 %) and alkali value (4.56). Significantly highest total chlorophyll content (4.61 mg g-1 fresh leaves) was also observed with P2 among the P management practices and a value of 4.46 mg g-1 fresh leaves chlorophyll content was recorded in rice variety Pratikhya. Microbial biomass carbon increased up to 30 days after transplanting (DAT) and decreased thereafter up to 45 DAT irrespective of phosphorus doses and rice varieties. The soil dehydrogenase activity was increased due to application of different doses of phosphorus and rice variety irrespective of growth stages. P uptake by rice was estimated highest with P2 (100% of STD for P to both the crops) and cv. Pratikhya responded better among the varieties.