Abstract
Nitrogen is an important element that affects the growth and yield of rice obviously. To explore the effects of nitrogen (N) on the growth of double-cropping rice, four consecutive trials were conducted in South China Agricultural University. Four N forms and five N application rates were set up. Rice N uptake, leaf anatomic structure, leaf fluorescence parameters and yield were studied. The results showed that rice leaf SPAD value and N content with urea treatment were the highest among 4 N forms at the heading and flowering stage. The order of rice yield and N use efficiency treated with different N forms were urea > ammonium sulfate > ammonium nitrate > sodium nitrate. The N application rate test showed that photochemical quantum efficiency and chemical quenching coefficient of rice leaves showed an inverted-V-type changing tendency with the highest value at 180 kg/hm2 N treatment. Treatment with less than 180 kg/hm2 N decreased the area and perimeter of small vascular bundles of the lateral leaves. Yield of early rice and later rice with 180 kg/hm2 urea treatment was 17.42 to 33.28% and 6.17 to 21.28% higher than those of other N levels, respectively. The above results suggested that 180 kg/hm2 of urea N are suitable and recommended for double-cropping rice planting in South China.
Highlights
Rice is the most important food crop in China, with a planting area of 31.857 million hectares
The results indicated that the Soil and plant analyzer development (SPAD) value of the top leaf of rice showed a gradual upward trend from the tillering stage to the jointing–booting stage, and a
The results indicated that the SPAD value of the top4 leaf of 12 of rice showed a gradual upward trend from the tillering stage to the jointing–booting stage, and a downward trend from the heading–flowering stage to the maturity stage
Summary
Rice is the most important food crop in China, with a planting area of 31.857 million hectares. Few studies have reported on N fertilizer incorporation technology for rice planting several times a year in South China. The selection of suitable N fertilizer forms and N application rate was an important measure to improve the photosynthetic capacity and increase rice yield [7]. ‘Zeng Cheng Si Miao’ (ZCSM) is one of the main cultivars of the rice-producing areas of South China and was listed as a national geographical indication protection product in 2004. ZCSM was used, as materials, the effects of different N forms and dosages on rice N uptake, photosynthetic characteristics and yield were investigated during the key growth period of double-cropping rice plants, so as to explore an optimal nitrogen application model suitable for the production of double-cropping rice planting in South China
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