질소 추비 시 질소구배에 따른 밀의 생육과 초분광 반사율 변화

초록

This study was conducted to analyze changes in growth and physiological characteristics of winter wheat under different nitrogen top-dressing levels, and to identify vegetation indices from hyperspectral reflectances. The experiment was carried out over two growing seasons (2019 - 2021) at the Gyeongsang National University Experimental Farm. Based on the standard nitrogen application rate, 40% of the fertilizer was applied as a basal treatment, while topdressing was applied at seven levels (GN1 to GN7) ranging from 0% to 120%. Growth characteristics, including plant height, leaf area index (LAI), and photosynthetic traits, were investigated. Hyperspectral reflectance of emerging leaves was measured, and vegetation indices were calculated. As nitrogen topdressing rate increased, plant height, SPAD value, LAI, and photosynthetic rate also increased. Fv/Fm values were higher in GN4 to GN7 though relatively low in GN1. Hyperspectral reflectance showed differences in the visible light region depending on nitrogen treatment. NDVI and BI increased with higher nitrogen levels; NDVI showed a significant positive correlation with nitrogen during both the elongation and heading stages, while BI was significantly correlated during the heading stage. In contrast, SIPI decreased as nitrogen topdressing increased, showing a significant negative correlation at the heading stage. GI and RI also decreased with increasing nitrogen, but their sensitivity was lower compared to other vegetation indices. These results confirm that NDVI and BI effectively reflect the nitrogen status and growth characteristics of winter wheat, while SIPI effectively indicates leaf senescence and pigment composition changes caused by nitrogen supply. Therefore, these vegetation indices have strong potential as non-destructive tools for nitrogen management and growth diagnosis in wheat.

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