Temporal change in canopy reflectance at visible wavelength as a biophysical indicator of jute (Corchorus capsularis L.) growth

Abstract

Changes in the reflectance and transmittance of jute canopy at different visible wavelengths of solar radiation are measured at different growth stages throughout the period of half crop cycle. The reflectance is found to gradually decrease and attain a steady value with canopy growth up to about one‐third of the crop cycle. As an independent study, vegetation growth parameters such as canopy height, leaf length, leaf area are simultaneously measured. It is concluded that although these parameters have individual properties, the whole canopy ultimately occupies a constant fraction of the air volume over the soil. As a combined effect of the above parameters, the transmittance through the leaf–air composite becomes saturated. A suitable mathematical explanation is given for the above. It is affirmed from these two independent sets of experiments that the vegetation growth is truly echoed in the temporal change in visible wavelength reflectance, the remotely sensible parameter. Thus the present work proposes a methodology for remotely observing the growth of vegetation and it is justified with jute, an important cash crop in eastern India.

Acknowledgment

The authors wish to acknowledge the financial assistance of the University Grants Commission, India and the kind cooperation and suggestions of Dr P. Palit (Central Research Institute of Jute and Allied Fibres, Barrackpore, W.B., India). The participation of Mr A. Maulik (formerly with the Department of Physics, Presidency College, Kolkata, India) is also acknowledged with thanks.