Panicle characteristics, yield and their correlation in system of rice (Oryza sativa) intensification and conventional transplanting under variable irrigation, spacing and varieties

Abstract

System of rice (Oryza sativa L.) intensification (SRI) is a recent breakthrough in rice production technology. Tiller-production with healthy panicles, the key determinant of high yields under SRI, is variety and agronomic management dependant. This experiment was laid-out in a factorial RBD during rainy seasons of 2008 and 2009 in the tarai belt of northern India using fourteen treatments comprising of three irrigation schedules viz., irrigation at 1, 3 and 5 days after disappearance of ponded water (DADPW), two spacing intervals (20 cm × 20 cm, 25 cm × 25 cm) and two varieties ('Pant Dhan 4', 'Arize 6444') under SRI, and two controls consisting of conventional culti-vation (CT) of two varieties. In 2008, irrigation effects were non-significant, while in 2009, irrigation at 1 and 3 DADPW caused 19.3-38.5% and 9.3-22%, respectively, higher number of filled spikelets/panicle, and recorded higher panicle weight and lower sterility percentage than 5 DADPW. Overall advantage in grain yield due to irriga-tions at 1 and 3 DADPW was 8.6 and 5.8%, respectively over 5 DADPW (5.82 t/ha). Wider spacing resulted in heavier panicles and higher grain yield than narrow spacing. Between two varieties, 'Arize 6444' produced higher number of filled spikelets in all type of tillers. SRI improved the panicle characteristics and increased grain yield by 16.9% over CT (5.22 t/ha). Number and weight of filled-spikelets/panicle of primary and secondary tillers were cor-related with grain yield. Under SRI, varieties which produce large number of primary and secondary tillers with heavier panicles and a few or no tertiary tillers should be planted as panicle weights of tertiary tillers did not show significant correlation with grain yield. Further, SRI-rice should be planted at 25 cm × 25 cm spacing and irriga-tions should not be delayed beyond 3 DADPW.