PATH-COEFFICIENT ANALYSIS OF DIRECT-SEEDED RICE YIELD AND YIELD COMPONENTS AS AFFECTED BY SEEDING RATES

Understanding relationships among rice yield and yield components is critical to utilizing them effectively. Interrelationships among rice yield and yield components for direct seeded rice cultural systems using path-coefficient analysis that describes a cause-and-effect relationships have not been shown. To study these relationships as affected by seeding rates, our experiments were seeded at 50, 100, 150, 200 and 250 kg ha -1 in 1997-98 dry season and at 25, 50, 100, 150 and 200 kg ha -1 in 1998 wet season with two rice groups (very-early and early growth duration). As seeding rates increased, panicles per square meter (sqm) significantly increased, and filled grain per panicle significantly decreased, this indicated an indication of the compensatory nature between these two traits. Path-coefficient analysis revealed that filled grains per panicle had the positive direct effect on rice yield and compensated for decreasing panicle density. Grain weight was a varietal trait and was of secondary importance in determining rice yield. Unfilled grain percentage was affected by season. Considering good field management, the seeding rate of 100 kg ha –1 should be recommended and to achieve optimum rice yield and grain quality in direct-seeded cultural system, adequate panicles per sqm of uniform maturity must be obtained.