关键词: 水稻, 差值植被指数, 追肥调控, 产量, 氮肥利用率

Abstract:

【Objective】 The objective of the study is to estimate nitrogen (N) status of rice plant and recommend top-dressing N amount based on canopy reflectance spectra, so as to achieve higher yield, better grain quality and higher economic efficiency. 【Method】 The amounts of nitrogen fertilizer recommended for top-dressing of different treatments with varied basal N rates were calculated with the newly developed N top-dressing model based on plant N accumulation, which was estimated from differential vegetation index (DVI). Then the N top-dressing regulation effect was studied. 【Result】 The results showed that plants of different treatments with varied basal N rates had different N accumulations at the elongation stage. The treatments with high, medium and low basal N rates needed low, relative higher and high N fertilizer supplies, respectively. After N top-dressing, the differences of plant N concentration (PNC) and DVI between the regulation treatments and their CKs were induced gradually. And leaf photosynthetic rates (Pn) of the regulation treatments were significantly increased compared with their CKs. And higher economic benefits were also achieved in regulation treatments than its CKs. Compared with the normal high yield N treatment, the regulation treatments obtained higher Pn, dry matter accumulation, plant N accumulation, grain yield and nitrogen agronomic efficiency.【Conclusion】 Compared with the normal methods, the real-time top-dressing regulation technique based on reflectance spectra can quantify varied N top-dressing amounts induced by different plant and soil N status, so it is recommended for N top-dressing in rice.

Key words: rice, difference vegetation index, top-dressing regulation, yield, nitrogen use efficiency