Study On Nitrogen Nutrition In Maize Seedling Stage Based On Hyperspectral Imaging

Maize is a tr aditional gr ain crop in China, which has an important role in the compos ition of grain. Nitrogen, as one of the essential elements dur ing the growth and development of maize, is widely used in crop pr oduction. Ther efor e, in order to improve the rate of nitr ogen fertilizer applic ation, the increase of grain yield of maize has become one of the res earch topics of modern agr iculture. With the development of science and technology, the applic at ion of hyperspectral imaging technology in crop growth monitor ing and quality inspection of agr icultur al products has become mor e and more w idely. The r esearch object of this study was Heyu19 and Heyu 20, which was very common in Heilongjiang Province. And the research study the monitor ing on maize nitrogen by us ing hyperspectr al technology.The study completed the acquis ition and tr ansmiss ion of hyperspectr al images of the canopy by using the Hyp erspec soft wa re with A me ric an Head wa ll imag ing spect ro met er based on fie ld e xpe riment o f Ma ize und er d iffe rent n it rogen leve ls. The leaves wer e dete rmined the a mmon iu m nit rogen content by the Ge rman AA 3 ana ly ze r. In th e ma ize canopy image co llect ion, unde r d iffe rent lev e ls of n itrog en, the ma ize canopy spect ra l re flectan ce sho wed th e sa me regu la rity. Ther e were peaks at 560 nm and 700-750 nm. When the wavelength was larger than 780 nm, the ref lection plot for med a high r ef lectance cur ve. There was “two peaks” phenomenon for the r ed edge of canopy s pectra of corn. There was “r ed shift” phenomenon for the pos ition of red edge. According to the maize hyperspectral r ef lectance and the peak of red edge pos ition, it could be qualitatively distinguish for ser ious ly def ic ient nitr ogen and normal nitrogen and excess nitrogen. In th is e xpe riment, we chose the va riab le o f veg etat ion inde x to rep la ce the sensit ive b and, by gr ay- level segmentation method and spectral f eature analys is method. By us ing the method o f g ray leve l segmentat ion, 762 n m was se lected as the ch aracte ristic wave length; by us ing spect ra l featu re ana lys is method, the 720 n m was used as the ch aracte ristic wave length; by us ing the co rre lat ion mat rix ana lys is method, the forty-th ird b ands, fifty-seventh bands, 102 nd bands, 107 th b ands and 168 th bands we re used as the ch aracte rist ic bands. The cha ra cte ristic wav e length band was as a va riab le in the v egetat ion inde x. Nit rogen content o f ma ize leav es at N1 leve l was high er with ma ize canopy veget at ion inde x NDVI, RSI（715 n m, 700 n m）, DSI（700 n m, 566）,（n m）, NDSI（715 n m, 700 n m）. At N0, N3 n it rogen lev e ls, corn le af n it rogen content and co rn canopy spect ra l veget at ion ind e x NDVI, RSI（895 n m and 700 n m） and RSI（715 n m and 700 n m）, DSI（700 n m, 566 n m）, DSI（895 n m and 700 n m and 525 n m）, NDSI（715 NM and 700 n m） co rre lat ion was h igh e r. Then th e vegeta t ion inde x was used to p red ict the canopy content of Ma ize Seed ling stage, At N0, N1, N3 app lic at ion n it rogen leve l in ma ize canopy nit rogen content p red ict ion mode l werey = 0.529NDVI²- 0.150 NDVI + 2. 419 、y = 6.844 NDVI²-6.259 NDVI + 4. 167 、y = 2. 644 + 0.720 NDVI + 0. 725 NDSI_{715 nm, 700 nm}- 0.045DSI_{895 nm, 700 nm, 525 nm}, R² wer e 0.719, 0.803, 0.657, respectively. The established r egr ession model was ver if ied by F- test, and the F value were 0.170, 0.219 and 0.270 respectively, which is less than F0.05, and the models could be used.