Abstract: The possibility of using digital photography analysis technology to monitor the N status of fertilized alfalfa at budding stage was investigated with adding different exogenous nitrogen using a pot experiment. Results showed that the greenness intensity (GI) from alfalfa canopy image had significant inverse linear correlations with the conventional N diagnosis parameters of SPAD readings, above-ground biomass and N uptake. However the blueness intensity (BI) had no significant correlation with alfalfa N indices. The highest correlation coefficient (r) was -0.817 between SPAD and GI. Therefore, the method of visible digital image color analysis could be used for the fertilized alfalfa N diagnosis at budding stage in this experimental condition.

Key words: Digital photography, Alfalfa, Nitrogen status

摘要： 利用图像处理技术分析不同外源氮素添加下紫花苜蓿(Medicago sativa L.)现蕾期的冠层图像,并测定不同外源氮素添加试验下其叶片SPAD值、地上植株生物量和植株全氮量,初步研究了可见光遥感技术对苜蓿冠层氮营养诊断的可行性,对表征苜蓿氮营养状况的可见光光谱诊断指标进行了统计分析。结果表明:绿光值、红光值都与苜蓿叶片SPAD值、地上生物量和植株全氮量存在显著或极显著的线性负相关关系;而与蓝光值没有达到显著相关。其中,绿光值与苜蓿叶片的SPAD值极显著相关且相关系数最高(r=-0.817,P<0.01)。结果比较分析认为,数字图像的绿光值(GI)能够对现蕾期紫花苜蓿进行较好的营养诊断,因此利用可见光光谱形成的数字图像指导大田生产紫花苜蓿对其现蕾期氮营养诊断成为可能。

关键词: 数字图像技术, 紫花苜蓿, 氮营养诊断