Growth dynamics and yield of rice genotypes grown in transplanted and direct-seeded fields

Abstract

This study was conducted during the dry season 2005 at the experimental farm of the Philippine Rice Research Institute (PhilRice) in Maligaya, Science City of Muñoz, Nueva Ecija, Philippines to assess the growth dynamics of rice genotypes consisting of two hybrids (SL-8 and BIGANTE), two inbreds (PSBRc82 and IR72) and 1 new plant type (IR72967-12-2-3) when grown in transplanted and in direct seeded fields at recommended (50 kg ha^-1) and low seed density (25 kg ha^-1) and to identify morphological plant characteristics that contribute to higher grain yield. Direct-seeded rice had higher crop growth rates during vegetative stage than transplanted rice, exhibits leaf area development and greater dry matter accumulation. Transplanted seedlings exhibited transplanting shock which delayed crop establishment and reduced tillering and leaf areas. This led to higher yields of all genotypes under broadcast seeding. Of the two seeding densities, significantly higher yield was obtained in low seeding (SB25) than in broadcast seeding at 50 kg ha^-1and transplanting. At low seed density of 25 kg/ha, the hybrids had faster and better growth rate during the vegetative stage. Of the two hybrids, SL-8 had more erect leaves, higher canopy, longer stem length, and greater leaf area in direct seeded field at 25 kg/ha. At 84 days after sowing, SL-8 and BIGANTE have achieved optimum LAI 8.55 and 7.2, respectively. Although this was not significantly different with BIGANTE, SL-8 had the highest grain yield at 10.58 t/ha. The better performance of hybrids under direct seeding and at low seeding density suggests that these hybrids can be established in this method other than the usual transplanting in irrigated areas.