| Agroforestry system,as a high-yield agricultural and forestry management mode,has long been welcomed by the vast number of farmers.In agroforestry systems,light resource is considered to be one of the most important factors affecting crop growth on the basis of water and fertilizer resources have been satisfied in the agroforestry system.However,the previous research focused on the total light intensity and photosynthetic effective radiation in the system,and the quantitative analysis of the proportion of light quality and light quality was very little.In this paper,the 5 year and 10 year old walnut plantation in the hilly area of the southern TaiHang mountain was used as the research object,combined with the canopy parameters of walnut trees,the total irradiance(total light intensity),light qualitiy irradiance(light qualitiy intensity)and the light quality parameters are studied in time and space variation characteristics in Walnut plantation,aimed to provide theoretical basis for optimize the Plant configurationnorth,improving land utilization and productivity in the Agroforestry system in the hilly area of the southern TaiHang mountain.The main results are as follows:(1)From July to September,the 5a and 10a walnut LAI showed a tendency to increase first and then decrease.Under the canopy,the DIFN was the opposite of LAI,showing the first decreasing and increasing state.The difference between 5a and 10a walnut trees was the largest in August and the smallest in September.(2)The total irradiance under 5a and 10a walnut plantation reached the maximum at about 12:00 at noon,and the total irradiance reduction rate appeared at 10:00 in the morning.From July to September,the total irradiance decreased gradually,and its reduction rate was August>July>September.The total irradiance under 5a and 10a walnut plantation showed the largest in M,the smallest in E0.5,and the west side of the tree row was higher than the eastern side.The difference between the 5a and 10a walnut plantation was the largest in W1.0,the smallest in M,and higher in the western side than in the corresponding east side.(3)The light qualitiy irradiance of daily,monthly and spatial variation characteristics were the same as the Total Irradiance in 5a 10a walnut plantation.The contrast of light qualitiy irradiance showed that the reduction rate and difference of the blue violet irradiance in the band of photosynthetic effective radiation was the largest,the red orange light was the second,the yellow green light was the smallest,the infrared irradiance subtracting rate and the difference were smaller in the infrared band,and the near infrared was larger.(4)The fluctuation range of B/FR,R/FR and NR/FR in the 5a and 10a walnut plantation was large,and its value and reduction rate were all lowest at about 10:00 in the morning and the low value at 16:00 in the afternoon.From July to September,B/FR,R/FR and NR/FR all showed September>July>August,and their reduction rates were August>July>September.The B/FR,R、FR and NR/FR under 5a and 10a walnut plantation were the largest in M,the smallest in E0.5,and the west side of the tree row were higher than that in the eastern side.The difference between 5a and 10a walnut plantation was the largest in W1.0,the least in M,and the western side were higher than the eastern side of the corresponding counterparts.Among the three light quality parameters,the reduction rate and the difference of B/FR was the largest,followed by R/FR and NR/FR was the smallest.In the production practice,the demand and sensitivity of the total irradiance,light qualitiy irradiance and the light quality parameters should be considered according to the Phenophase of the crops,and select the suiTab.intercrops with the light resources under the forest to improve the land productivity and the utilization of light energy. |
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