Late-season nitrogen applications improve grain yield and fertilizer-use efficiency of dry direct-seeded rice in the tropics

• Published in: Field crops research Vol. 233; pp. 114 - 120
• Main Authors: Liu, Hongyan, Won, Phyo L.P., Banayo, Niño P.M., Nie, Lixiao, Peng, Shaobing, Kato, Yoichiro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2019
• Subjects: Dry-seeded rice; Grain yield; Leaf senescence; N management; Tropical rice; IRRI; LAI; Dry-seeded rice; Grain yield; N management; Leaf senescence; NAR; CGR; Tropical rice
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/j.fcr.2019.01.010

•We evaluated late-season N application (LSNA) in tropical dry direct-seeded rice.•N recovery increased with an increasing proportion of N input at later stages.•LSNA increased the percentage of filled grains and harvest index.•LSNA increased yield by 6% in the dry season and 7% in the wet season. Efficient nitrogen (N) management plays an important role in rice cultivation. Previous studies in the tropics mainly focused on split-N applications before panicle initiation in transplanted rice. In this study, we examined the effects of top-dressing at panicle initiation and flowering of dry direct-seeded rice on yield and fertilizer-use efficiency in field experiments at the International Rice Research Institute, the Philippines, in the dry and wet seasons. Two high-yielding indica cultivars (Rc222 and Rc282) were drill-seeded under four split-N application regimes and a control with no supplemental N. The timing of the split-N applications significantly affected grain yield, even though the total N input was unchanged. The late-season N application at heading increased yield by 6% (0.49 t ha−1) in the dry season and 7% (0.49 t ha−1) in the wet season. The N recovery efficiency also increased with an increasing proportion of N applied at later growth stages. The yield advantage of the late-season N application over the early-season N application (seeding to panicle initiation) may be attributable to delayed senescence (maintenance of more and greener leaves toward maturity), higher canopy photoassimilation, greater grain-filling, and a higher harvest index. Our results underline the importance of late-season N application in dry direct-seeded rice under favorable lowland conditions in the tropics. The optimal split-N regimes during the vegetative stage may depend on the season or temperature regime, so this subject requires additional investigation.