Differential response of phosphorus utilization efficiency in rice by tracer technique using phosphorus-32 under phosphorus stress environment

In most soils, soil and fertilizer Phosphorus (P) are easily bound by either soil organic matter or chemicals and thus are unavailable to plants unless hydrolyzed to release inorganic phosphate. Therefore, the development of P-efficient rice varieties that can grow and yield better with low P supply is a key to improve crop production. P efficient plants play a major role in increasing crop yields due to shortage of inorganic P fertilizer resources, limited land and water resources and increasing environmental concerns. Based on the P uptake efficiency, four rice genotypes viz.,TNRH 180, CB08504, CB06732 and ADT 47 were selected from the field experiment and used in pot culture experiment with three levels of P using radio isotope technique to quantify the P acquisition efficiency (PAE) and P use efficiency (PUE) and also to determine the native P supplying power of the soils using 32P in low P soils. Growth and yield parameters, grain and straw yield and major nutrients uptake of rice genotypes were increased with enhanced level of phosphorus application. Among the four genotypes, TNRH 180 recorded the highest grain yield and uptake. Increasing the P application rate from 25 to 50 kg P2O5 ha-1 increased the %Pdff in grain and straw for all the genotypes. The mean per cent phosphorus utilization (PPU) ranged between 18.74 and 23.72. The PPU of the genotypes followed the order TNRH 180 (23.72 %) > CB08504 (23.36 %) > CB06732 (20.54%) > ADT 47 (18.74%). The PPU values were higher at lower level of P application (25 kg P2O5 ha-1) for the genotypes TNRH 180, CB08504 and CB06732. From this study showed that rice genotypes have the ability to utilize the both available and unavailable form of phosphorus by secreting some organic acids in the root portion to solubilize. Hence rice genotypes indicated above have the ability to increase phosphorus utilization efficiency