LOWLAND RICE GENOTYPES EVALUATION FOR PHOSPHORUS USE EFFICIENCY IN TROPICAL LOWLAND

Abstract

Lowland rice is a staple food for more than 50% of the world's population and phosphorus (P) deficiency is one of the main constraints in rice production in tropical lowlands. A field experiment was conducted for two years consecutive with the objective to evaluate 12 lowland rice genotypes for P use efficiency. The P rates used were 0, 22, 44, 66, and 88 kg P ha⁻¹ (0, 50, 100, 150 and 200 kg P₂O₅ ha⁻¹) applied to an Inceptisol. The genotypes used were BRS Jaçanã, CNAi 8860, BRS Fronteira, CNAi 8879, CNAi 8880, CNAi 8886, CNAi 8885, CNAi 8569, BRSGO Guará, BRS Alvorada, BRS Jaburu and BRS Biguá. There were significant and quadratic responses of genotypes to phosphorus fertilization. Adequate P rates for maximum grain yield varied from genotype to genotype. However, across 12 genotypes, maximum grain yield was obtained with the application of 54 kg P ha⁻¹. Genotype BRS Jaçanã was most efficient and genotype CNAi 8569 was most inefficient in P use efficiency. Shoot dry weight and panicle number was also increased significantly and quadratically with increasing P rates in the range of 0 to 88 kg P ha⁻¹. These two plant parameters were positively associated with grain yield. Agronomic efficiency (kg grain produced per kg P applied) was significantly decreased with increasing P rates in the range of 22 to 88 kg P ha⁻¹.

Keywords:

• agronomic efficiency
• grain yield
• Inceptisol
• yield components