Abstract: Solar radiation (300 - 1 010 nm),photo synthetically active radiation (PAR,380 - 720 nm),ultraviolet radiation (U,300 - 380 nm),infrared radiation (R/ FR,780 - 1 010 nm),transmission rate of solar direct radiation and diffused radiation of apple ( Malus domestica Borhk. cv. Fuji) were measured under the field with the center2open and small canopy trepanning system at Beijing from 2004 to 2007. The result showed that :when solar radiation passed through canopy,radiation spectrum changed greatly.At 530 - 560 nm and 738 - 746 nm,the radiation reduced significantly,and at 738 - 746 nm,the radiation reduced slowly. The ratio of transmission of center2open trepanning system was higher than that of small canopy trepanning system. The ratio of PAR,U and R/ FR radiation were different in different canopy. From surface to inner of the canopy,the ratio of PAR was decreased and the ratio of U and R/ FR radiation were increased. The intensity of PAR,U and R/ FR radiation decreased from surface to inner of the canopy. The intensity of solar radiation, PAR,U and R/ FR radiation were different in different canopy. Fitting equations showed that,when solar radiation and PAR passed through canopy,their radiant intensity decreased in the way of exponential function ;and when U and R/ FR passed through canopy,their radiant intensity decreased in the way of logarithmic function or polynomial function.

Key words: Canopy, Solar radiation, Light quality, Microlight environment

CLC Number: 

• S1.1