水稻冠层叶片SPAD数值变化特征及氮素营养诊断

建立水稻Oryza sativa氮营养诊断模型，实时反映水稻植株氮素营养状况，对水稻田间管理至关重要。于2015年在浙江省德清市开展田间试验，选择‘甬优538’‘Yongyou 538’和‘秀水134’‘Xiushui 134’作为代表品种，设置5个施氮水平0（N₀），70.0（N₁），140.0（N₂），210.0（N₃），280.0（N₄）kg·hm-2，通过研究不同施氮水平下2个水稻品种冠层叶片作物分析仪器开发值（SPAD）变化规律，探究5个不同施氮水平下植株氮质量分数的变化趋势，并利用归一化SPAD指数（I_NDSPAD14）估算植株氮质量分数。结果表明:顶4叶相较其他叶片更能指示水稻植株氮质量分数，归一化SPAD指数与N₀~N₄所有不同施氮量组别之间冠层叶片氮质量分数呈显著正相关（P < 0.05），‘甬优358’水稻品种决定系数为0.69~0.96，‘秀水134’品种决定系数为0.64~0.94。该指数可以对水稻冠层叶片氮质量分数快速估测。

Characteristics and diagnosis of nitrogen nutrition for rice canopy leaf SPAD value changes

Nitrogen(N) is important for rice growth. To establish a rice (Oryza sativa) nitrogen nutrition diagnostic model that could reflect the N status of a rice organism and that could be convenient for rice field management, a rice community test was conducted in Deqing City, Zhejiang Province in 2015. Oryza sativa 'Yongyou 538' and 'Xiushui 134' were taken as the representative cultivars. Five levels of N were established:0(N₀)(ck), 70.0(N₁), 140.0(N₂), 210.0(N₃), and 280.0(N₄) kg·hm-2. Measurement of rice SPAD (soil and plant analyzer development) values were made using a portable SPAD-502 meter and followed by a correlation analysis. Results showed that the fourth leaf from the top was a good indication of plant nutrition status. There was a significant positive correlation between the normalized SPAD index (I_NDSPAD14) and N content in canopy leaves with the N₀-N₄ treatments. The coefficients of determination for 'Yongyou 358' r2=0.69-0.96 and for 'Xiushui 134' r2=0.64-0.94. By analyzing the relationship between I_NDSPAD14 and plant N content, a diagnostic model of rice N concentration was established.