1.中国农业大学, 现代精细农业系统集成研究教育部重点实验室，北京 100083 2.Department of Agricultural Engineering, Agricultural University of Athens, Athens, Greece
Nitrogen Content Testing and Diagnosing of Cucumber Leaves Based on Multispectral Imagines
YANG Wei1, Nick Sigrimis2, LI Min-zan1*
1.Key Laboratory of Modern Precision Agriculture System Integration Research，Ministry of Education, China Agricultural University, Beijing 100083, China 2.Department of Agricultural Engineering, Agricultural University of Athens, Athens, Greece
Abstract：Using CCD camera and special filters, the growth parameters of cucumber plants, the nitrogen content and the area of leaves, were investigated in an experimental greenhouse.In order to make nutrient stress to the plants, different nitrogen levels were prepared.The basic nitrogen content was 0.067 kg·L-1 and four different levels of nitrogen contents were made to be 2, 1, 0.5, and 0.2 N, respectively.The genetic and water-segment methods were used to separate IR and R2 images from the background.It was found that the result of water-segment is better.It has clearer boundary, less noise and closer result to the original image.After the reflectance information of cucumber leaves was obtained, the vegetation indexes, RVI, NDVI and GNDVI, were calculated and then the correlation coefficients between each vegetation index and nitrogen content or leave area were analyzed.The result shows that there is an obvious linear correlation between NDVI and nitrogen content of leaves or leave area and the R2 are 0.820 9 and 0.701 7, respectively.The high correlations were also observed between GNDVI and nitrogen content of leaves or leave area, and the R2 are 0.762 5 and 0.676 2, respectively.The reason is that the reflectance of IR is mainly affected by reflectivity and the canopy structure of cucumber leaves.As biomass and area of leaves increase with the nitrogen content, the reflectivity of leaves becomes stronger.And the gap among cells of high nitrogen content leaves is large.Cell wall has more water, which has a strong effect on the reflectivity of NIR.At visible wavelength, the reflectance of cucumber leaves decreases as nitrogen content increases since the chlorophyll content increases as nitrogen content increases.The trend of correlation between RVI and nitrogen content disagreed with that of the correlation between RVI and leave area.There is an obvious linear correlation between RVI and leave area, and the R2 is 0.857 7.However, the correlations between RVI and nitrogen content exhibit a nonlinear relationship, and R2 is only 0.598 8.It is because as cucumbers grow older, the reflectance of canopy increases at visible wavelength but decreases at near infrared wavelength.The experimental result proves that CCD camera and special filters can be used as a good method for diagnosing nitrogen content of cucumber plants.
杨 玮1，Nick Sigrimis2，李民赞1* . 基于多光谱图像分析的温室黄瓜叶片营养元素检测与诊断[J]. 光谱学与光谱分析, 2010, 30(01): 210-213.
YANG Wei1, Nick Sigrimis2, LI Min-zan1* . Nitrogen Content Testing and Diagnosing of Cucumber Leaves Based on Multispectral Imagines . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2010, 30(01): 210-213.
[1] Thomas J R, Gausman H W.Agronomy Journal, 1977, 69: 799. [2] Al-Abbas A H, Barr R, Hall J D, et al.Agronomy Journal, 1974, 66: 16. [3] Shibayama M, Akiyama T.Remote Sensing of Environment, 1999, 27: 119. [4] XUE Li-hong, LUO Wei-hong, CAO Wei-xing(薛利红, 罗卫红, 曹卫星).Journal of Remote Sensing(遥感学报), 2003, 7(1): 73. [5] FENG Wei, ZHU Yan, TIAN Yong-chao, et al(冯 伟, 朱 艳, 田永超, 等).Journal of Ecology(生态学报), 2008, 28(1): 23. [6] ZHU Yan, YAO Xia, TIAN Yong-chao(朱 艳, 姚 霞, 田永超).Journal of Plant Ecology(植物生态学报), 2006, 30(6): 983. [7] ZHOU Dong-qin, TIAN Yong-chao, YAO Xia, et al(周冬琴, 田永超, 姚 霞, 等).Chinese Journal of Applied Ecology(应用生态学报), 2008, 2(19): 337. [8] SHENG Zhang-quan, WANG Ke, WANG Ren-chao(沈掌泉, 王 珂, 王人潮).Remote Sensing Technology and Application(遥感技术与应用), 1997, 12(2): 17. [9] WANG Ke, SHEN Zhang-quan, WANG Ren-chao(王 珂, 沈掌泉, 王人潮).Remote Sensing for Land & Resourses(国土资源遥感), 1999, 1: 9. [10] ZHOU Qi-fa, WANG Ren-chao(周启发, 王人潮).Journal of Zhejiang Agricultural University(浙江农业大学学报), 1993, 19(增刊): 40. [11] WANG Ren-chao, CHEN Ming-zhen, JIANG Heng-xian(王人潮, 陈铭臻, 蒋亨显).Journal of Zhejiang Agricultural University(浙江农业大学学报), 1993, 19(增刊): 7. [12] LI Min-zan(李民赞).Spectral Analysis Technology and Application(光谱分析技术及其应用).Beijing： Science Press(北京： 科学出版社)，2006.183. [13] WU Bing-fang, ZHANG Feng, LIU Cheng-lin, et al(吴炳方, 张 峰, 刘成林, 等).Journal of Remote Sensing(遥感学报), 2004, 8(6): 498. [14] YANG Bang-jie, PEI Zhi-yuan, ZHOU Qing-bo, et al(杨邦杰, 裴志远, 周清波, 等).Transactions of the Chinese Society of Agricultural Engineering(农业工程学报), 2003, 18(3): 191. [15] Jones C L, Maness N O, Stone M L, et al.Transactions of the ASABE, 2007, 50(5): 1867. [16] Sui R, Wilkerson J B, Hart W E, et al.Applied Engineering in Agriculture, 2005, 21(2): 167. [17] Lü Chao-hui, CHEN Xiao-guang, WU Wen-fu, et al(吕朝辉, 陈晓光, 吴文福, 等).Natural Science Journal of Jilin University of Technology(吉林工业大学自然科学学报), 2001, 31(3): 90. [18] ZHANG Yu-jin(章毓晋).Photo Process and Analyze(图像处理与分析).Beijing: Tsinghua University Press(北京： 清华大学出版社), 1999.
