Spectral monitoring of growth and development of cotton (Gossypium species)

摘要

Remote sensing technology is an important tool for monitoring crop growth and development. In order to study the spectral monitoring of growth and development of cotton, the field experiment was conducted on cotton crop during 1997-98 kharif seasonon a sandy loam soil at the Punjab Agricultural University, Ludhiana. Spectral reflectance and agronomic measurements were recorded for cotton species (American and desi cotton) sown on two dates (May 1 and May 29) under five nitrogen levels (0, 40, 80,120 and 160 kg/ha). The results showed that red and IR reflectance percentages were minimum and maximum, respectively at 110 DAS. These reflectances were lower and higher, respectively under desi cotton than American cotton throughout crop growth periods.May 1 sown crop showed higher red reflectance and lower IR reflectance percentages than May 29 sown crop. Comparatively higher red reflectance and IR reflectance were observed for the nitrogen deficient (control) as compared to fertilized crop. The plotting of spectral (RR and NDVI) and agronomic parameters v/s time during crop life cycle revealed that LAI and above ground dry matter accumulation can be estimated with spectral parameters. Both the cotton species can be distinguished spectrally from grand growth period on wards under normal and late sown conditions. But, within same cotton species, the crop under normal and late sowing can be remotely identified separately before and after the grand growth period of the crop. These parameters are usefulfor distinguishing nitrogen stressed and fertilized cotton crop. So, spectral parameters (RR and NDVI) can be used to monitor growth and development of both cotton species.