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以直立和平展2种株型的冬小麦品种为材料,研究了它们的光谱响应以及田间植被覆盖度的差异,探讨了利用冠层光谱反射率、光谱特征参量NDVI及植被覆盖度识别小麦株型的方法。结果表明,(1)小麦不同株型品种在近红外波段(700~1 300 nm)光谱反射率有明显差异,生育前期平展型品种高于直立型品种,并以拔节期的差异为最显著,随着生育进程差异逐渐变小。拔节期是进行株型识别的最佳时期,并且此期冠层的敏感波段680 nm和760~900 nm的反射率在2种株型品种之间差异明显。(2)小麦冠层叶面积指数(LAI)与归一化差异植被指数NDVI(680,890)呈正相关,并且不同生育阶段其相关程度有差异,这是利用NDVI和植被覆盖度(COV)识别不同株型的基础。(3)相同COV条件下,直立型品种的NDVI高于平展型品种的NDVI,并且随着COV的增加,差异逐渐变小,二者的变化关系体现了直立型品种株型紧凑和平展型品种株型披散的特点,利用NDVI和COV的关系可以对株型进行识别,以小麦拔节期为最佳识别阶段,此期2种株型品种的NDVI具有显著差异(P<0.05)。
The vertical and horizontal varieties of winter wheat were used as materials to study their spectral responses and differences in field coverage. The authors discussed the possibility of identifying plant type using canopy spectral reflectance, spectral characteristic parameters (NDVI) and vegetation coverage method. The results showed that: (1) The spectral reflectance of different plant types in wheat in the near infrared band (700 ~ 1 300 nm) were significantly different. The flat varieties at the early growth stage were higher than the erect varieties and the difference was the most significant at the jointing stage. As the difference in fertility progressively diminishes. The jointing stage is the best period for plant type identification, and the reflectance at 680 nm and 760-900 nm in the sensitive band of the canopy differs significantly between the two plant types. (2) The canopy leaf area index (LAI) of wheat was positively correlated with NDVI (680,890), and its correlation degree differed at different stages of growth. This was done by using NDVI and COV to identify different strains Type of foundation. (3) Under the same COV conditions, the NDVI of upright varieties was higher than that of flat varieties, and the difference became smaller with the increase of COV. The relationship between the two was the compact and flat varieties The relationship between NDVI and COV could be used to identify the plant type, and the wheat stage was the best identification stage. The NDVI of the two plant type cultivars in this period was significantly different (P <0.05).