利用遥感光谱无损、快速分析出氮肥的施用时期和施用模式,对于保护环境、产量及氮肥利用率的提高具有重要意义。利用FieldSpec 4Wide-Res Field Spectrum radiometer便携式地物光谱仪,测定了不同氮水平下小麦冠层和叶片两种模式光谱特...利用遥感光谱无损、快速分析出氮肥的施用时期和施用模式,对于保护环境、产量及氮肥利用率的提高具有重要意义。利用FieldSpec 4Wide-Res Field Spectrum radiometer便携式地物光谱仪,测定了不同氮水平下小麦冠层和叶片两种模式光谱特征及红边参数变化规律;提出一个新指数——归一化差异最大指数(normalized difference maximum index,NDMI),并分析其与叶面积指数(leaf area index,LAI)、SPAD(soil and plant analyzer development)值、MDA(malondialdehyde)含量、旗叶氮含量和产量的相关性。结果表明,小麦叶片原始光谱在开花后26d起800～1 330nm区间的光谱反射率以N3(1/3底施+1/3冬前追肥+1/3拔节期追肥)处理为最高,N1处理(1/2底施+1/2冬前追肥)次之。主要原因是由冬前和拔节期两个时期均施三分之一氮肥,增强了叶片光合能力。小麦冠层原始光谱,在400～700nm波段,N2(1/2底施+1/2拔节期追肥)处理最低;在760～1 368nm波段区间,由于群体结构不同,在开花期至灌浆中期N1处理的光谱反射率最高,N3处理次之;N3处理的冠层光谱反射率在开花后26和33d最高。建议用400～700和760～1 368nm波段的冠层原始光谱数据,分别来辨别小麦旗叶含氮量的高低及施肥模式。叶片模式下一阶微分光谱在500～750nm区间出现两个"峰",通过峰的位置偏移程度和偏移时期来估测施氮的模式。在670～740nm区间冠层一阶微分光谱值在开花期最高,开花后10d的一阶微分光谱值最低。在开花期至开花后10d N1处理的一阶微分光谱值高于N3处理;灌浆中期至开花后33dN3处理的一阶微分光谱值高于N1处理。可以通过一阶微分最大值来推测小麦所处的生育期和施肥的方式及施肥时期。在开花期至灌浆中期,冠层反射率一阶导数最大值(FD-Max)N1处理最高,N3处理次之;在开花后26～33d,N3处理的群体结构较其他处理密,导致其一阶导数最大值一直最高。四个处理叶�展开更多
The purpose of this study is to reveal the effects of historic climate change on rice yield over the middle and lower reaches of the Yangtze River, China, and to better adapt to climate change in the future. This stud...The purpose of this study is to reveal the effects of historic climate change on rice yield over the middle and lower reaches of the Yangtze River, China, and to better adapt to climate change in the future. This study presents the relation of temperature and precipitation and rice components from 1981 to 2003 at 48 early rice stations and 30 middle rice stations. It focuses on an analysis of three stages： flowering, pre-milk, and late milk. The results show that mean maximum temperature and mean daily precipitation at the stages of flowering and pre-milk are most related to early rice yield. Yield change of middle rice is mainly because of mean precipitation change at the flowering stage. Furthermore, percentage of undeveloped grain increases as mean maximum temperature rises at the flowering stage. Over-precipitation in the reproductive stage is a major reason for reduction in yield of early rice. Consecutive rainfall and continuous high temperature can have negative effects on middle rice yield. Global warming would affect middle rice more seriously than early rice.展开更多
文摘利用遥感光谱无损、快速分析出氮肥的施用时期和施用模式,对于保护环境、产量及氮肥利用率的提高具有重要意义。利用FieldSpec 4Wide-Res Field Spectrum radiometer便携式地物光谱仪,测定了不同氮水平下小麦冠层和叶片两种模式光谱特征及红边参数变化规律;提出一个新指数——归一化差异最大指数(normalized difference maximum index,NDMI),并分析其与叶面积指数(leaf area index,LAI)、SPAD(soil and plant analyzer development)值、MDA(malondialdehyde)含量、旗叶氮含量和产量的相关性。结果表明,小麦叶片原始光谱在开花后26d起800～1 330nm区间的光谱反射率以N3(1/3底施+1/3冬前追肥+1/3拔节期追肥)处理为最高,N1处理(1/2底施+1/2冬前追肥)次之。主要原因是由冬前和拔节期两个时期均施三分之一氮肥,增强了叶片光合能力。小麦冠层原始光谱,在400～700nm波段,N2(1/2底施+1/2拔节期追肥)处理最低;在760～1 368nm波段区间,由于群体结构不同,在开花期至灌浆中期N1处理的光谱反射率最高,N3处理次之;N3处理的冠层光谱反射率在开花后26和33d最高。建议用400～700和760～1 368nm波段的冠层原始光谱数据,分别来辨别小麦旗叶含氮量的高低及施肥模式。叶片模式下一阶微分光谱在500～750nm区间出现两个"峰",通过峰的位置偏移程度和偏移时期来估测施氮的模式。在670～740nm区间冠层一阶微分光谱值在开花期最高,开花后10d的一阶微分光谱值最低。在开花期至开花后10d N1处理的一阶微分光谱值高于N3处理;灌浆中期至开花后33dN3处理的一阶微分光谱值高于N1处理。可以通过一阶微分最大值来推测小麦所处的生育期和施肥的方式及施肥时期。在开花期至灌浆中期,冠层反射率一阶导数最大值(FD-Max)N1处理最高,N3处理次之;在开花后26～33d,N3处理的群体结构较其他处理密,导致其一阶导数最大值一直最高。四个处理叶�
文摘The purpose of this study is to reveal the effects of historic climate change on rice yield over the middle and lower reaches of the Yangtze River, China, and to better adapt to climate change in the future. This study presents the relation of temperature and precipitation and rice components from 1981 to 2003 at 48 early rice stations and 30 middle rice stations. It focuses on an analysis of three stages： flowering, pre-milk, and late milk. The results show that mean maximum temperature and mean daily precipitation at the stages of flowering and pre-milk are most related to early rice yield. Yield change of middle rice is mainly because of mean precipitation change at the flowering stage. Furthermore, percentage of undeveloped grain increases as mean maximum temperature rises at the flowering stage. Over-precipitation in the reproductive stage is a major reason for reduction in yield of early rice. Consecutive rainfall and continuous high temperature can have negative effects on middle rice yield. Global warming would affect middle rice more seriously than early rice.
