Abstract:

The vertical distribution of biomass, which indicated the characteristics of quantity and structure in canopy, is an important index of diagnosis and management for crop growth. However, traditional measurements are time-consuming and labor intensive and can result in significant mechanical damage to plants, such as layer upon layer cut method. The image processing technologies, which may provide more efficient and no-destructive methods for measurement, have recently appeared in the agronomic literature. This paper focused on the determination of biomass vertical distribution in the canopy of winter wheat, based on digital image processing technology. The digital images (2 272 by 1 706 pixels) were taken with digital camera of winter wheat rows in the field plots of an experiment during the 2004 to 2005 growing season. Excess Green image segmentation method was used to separate wheat population and background. At the same time, relative biomass weight was measured using layer upon layer cut method, and the distance between neighbor layers was 20 cm. The image pixels of a single row and biomass could fit regression relationship (R2D1=0.9682) much better than those of multiple rows and biomass. The regression relationship between the image pixels and dry matter weight much better than those and fresh matter weight. The estimating functions were established between biomass and pixel number (PN) in each layer (Y = 6×10-5X + 24.72), and between effective biomass and green pixel number (LGPN) in each layer (Y = 7×10-5X + 25.09), and meanwhile the vertical distribution of effective biomass and dynamic of winter wheat canopy under different management conditions was analyzed qualitatively with LGPN. Finally, an index, namely, image pixel vertical distribution index (I), with which vertical distribution of canopy biomass of winter wheat could be analyzed quantitatively, was determined. The results show that the application of digital image processing has significant potential for determination of vertical distribution of biomass in the canopy of winter wheat, and is one of the quick, real time and almost no-destructive measurements.

Key words: Digital image, Canopy of winter wheat, Biomass, Vertical distribution