Phosphorus deficit response between shoots and roots of rice (Oryza sativa L.) at stages before anthesis

Phosphates, carbohydrates, and antioxidants are explored less in the shoots and roots of rice plants under phosphorus (P)-deficit. P-fractionation is poorly understood in plants. Present study analyzed phosphates, carbohydrates, and antioxidants in the shoots and roots of rice cultivars, CSR10 (low-P tolerant) and Pusa44 (low-P susceptible) under P-deprivation (P₀) compared to P-application (30 kg ha⁻¹) (P₃₀) at 20 and 40 days after transplantation (DAT). Results found that total-P decreased at 20 DAT and increased at 40DAT in the shoots and roots of Pusa44; however, in CSR10, total-P increased in the roots at 20 and 40 DAT and in the shoots at 20 DAT however decreased in the shoots at 40DAT under P₀. At 40DAT, P was invested largely in lipid fraction while investments in inorganic and metabolic fractions were reduced in the shoots of Pusa44, and contrary to it, P reduced largely in lipid fraction while increased in inorganic and metabolic fractions in the shoots of CSR10 under P₀. Nucleic acid-P, RNA, and protein were most deficient in the roots of Pusa44 at 20 DAT under P_0. Sucrose, starch, and invertases increased in roots compared to shoots with high effect in CSR10 under P₀. Acid phosphatases and ribonucleases were more adequate in the roots of CSR10 than that of Pusa44 under P₀. Antioxidants were largely deficient in the roots of Pusa44 while increased in the roots of CSR10 under P₀. Results indicated that investment in metabolic-P and inorganic-P through reducing lipid-P and total-P in the shoots may be beneficial for low-P tolerance. Acid phosphatases, ribonucleases, and antioxidant activities of roots may be important for low-P tolerance.