Evaluation of rice genotypes for phosphorus use efficiency under soil mineral stress conditions

A field trial was conducted during wet seasons of 2004 and 2005, twenty-eight pre-release promising rice varieties and hybrids were evaluated for their grain yield, and response to graded levels of applied phosphorus in a low soil-P fertility status calcareous vertisol located at DRR farm, Rajendranagar, Hyderabad. Among rice cultures, four distinct patterns in grain yield response were observed with eight rice cultures at 0 P-level, six rice cultures at medium P- fertility level (20–30 kg P₂O₅ ha⁻¹) were exhibiting higher grain yield response; while five recorded higher grain yields and yield response only at higher P-levels of 50 – 60 kg P₂O₅ ha⁻¹ (65 – 93 kg grain kg⁻¹ P₂O₅) compared to others (16 – 66 kg grain kg⁻¹ P₂O₅). The other cultures IET 17190, Sumati and Rajavadlu did not show any grain yield response either at 0 – 10 or 50 – 60 kg P₂O₅ ha⁻¹; indicating the existence of genetic variability for P-use efficiency trait.