Portable active remote sensing spectrometer-Greenseeker and chlorophyll meter (SPAD 502) were used to determine NDVI and SPAD meter readings of corn at different growth stages under different nitrogen levels. This paper studied the impact of nitrogen on the nutritional status of single plant and corn population, and simple, fast and non-destructive nutritional diagnosis methods of crop nitrogen status in the field. The research results showed that NDVI increased with N rate, reaching a plateau at N 300 kg/hm^2. The relationship between NDVI and nitrogen rate could be described with a linear plus plateau model. Corn NDVT changed with different growth stages: NDVI was at a low level at the seeding stage and increased to the highest level at the pre-tasselling stage, then declined gradually and stabilized after tassel stage. The changes of NDVI and SPAD values showed similar trend. SPAD readings and chlorophyll contents were positively correlated, and SPAD readings at pre-tasselling stage were positively correlated with grain yield. This paper proved that portable active remote sensing spectrometer-Greenseeker and chlorophyll meter (SPAD meter) could be integrated to diagnose corn nitrogen nutritional status.
主動遙感光譜儀Greenseeker與SPAD對玉米氮素營養診斷的研究
以手持式主動遙感光譜儀Greenseeker和葉綠素儀SPAD對玉米不同氮素水平下各個生育期的NDVI值及葉片SPAD值進行測試，研究不同氮素對玉米群體和個體營養狀況的變化以及田間條件下簡便、快速、非接觸性的作物氮素營養狀況診斷方法。結果表明，在一定的范圍內隨著氮肥用量的增加NDVI值也增加，氮肥施用量為N 300kg/hm^2時NDVI值達到最高，NDVI與氮肥施用量符合線性加平臺的關系；玉米不同生育期間NDVI值變化明顯，苗期NDVI值比較低，大喇叭口期NDVI值達到最高，以后逐漸下降并在抽雄期后趨于穩定。SPAD值與NDVI值的變化趨勢相一致，SPAD值與葉綠素含量成正相關關系，大喇叭口期完全展葉的SPAD與產量存在正相關關系。手持式主動遙感光譜儀Geenseeker和葉綠素儀SPAD結合能夠對玉米的氮素營養狀況作營養診斷。