Abstract:

【Objective】 The purpose of this study was to investigate the effects of wheat-residue application and nitrogen (N) management on grain yield and quality and nitrogen use efficiency in direct-seeding rice. 【Method】 A mid-season japonica rice cultivar of Yangjing 9538 was directly sown in the field. Three treatments of N-fertilizer application, farmers’ N-fertilizer practice (FFP), site-specific N management (SSNM) based on chlorophyll measurement (SPAD) readings, and no N application, and with or without wheat residue application were conducted. Grain yield and quality and N use efficiency were determined. 【Result】In comparison with the wheat-residue removal treatment, the wheat-residue application (the residue was incorporated into soil) treatment reduced panicles, but increased spikelets per panicle, filled-grain percentages and 1 000-grain weight, therefore increased grain yield. This treatment also improved rice appearance and cooking qualities, under either SSNM or FFP. In comparison with FFP, SSNM increased grain yield, reduced the grain protein content, and improved rice cooking quality. In comparison with the wheat-residue removal plus FFP treatments, the wheat-residue application plus SSNM treatments enhanced the maximum grain filling rate and mean grain filling rate and shortened the active grain filling period, leading to an increase in grain weight. Such treatments increased N harvest index, N recovery efficiency, N agronomic use efficiency, N physiological efficiency, and N partial factor productivity. 【Conclusion】 The results suggest that wheat-residue application combined with SSNM could not only increase grain yield and quality, but also improve N use efficiency in direct-seeding rice.

Key words: rice, direct-seeding, wheat residue incorporation, farmers’ fertilizer-N practice, site-specific nitrogen management, grain yield, quality, nitrogen fertilizer use efficiency