[Background] Agroforestry complex system has obvious ecological benefits of soil and water conservation in the Loess Plateau region.Recently,the research about agroforestry complex focused on the competition of water and nutrient,and neglected effects of solar radiation.Solar radiation is energy sources of intercropping,and crown shading should be focused in agroforestry complex system.Jinxi is a typical Loess Plateau region,where agroforestry complex is widely used.Thus,this study,measuring crown shadings of different age's (4 years,5 years,6 years,and 7 years) apple trees in Jinxi Loess Plateau area,aims to explore shading range that is shade area at corresponding moment within a day,repeated shading area that is an area continuously covered by apple tree crown within a day,and lasting shading time in a repeated shading area on different ages apple tree.[Methods] Based on similarity principle in parallel solar rays,the research established 3D apple tree model by reducing the 50 times of an actual apple.Apple tree shading range in a day was measured using the 3D tree.The shade was described based on the shadow of the 3D apple tree model in solar rays.The drawing describing shade range was imported to computer,and combining the software of CAD and MATLAB,the crown shade of apple tree within a day was analyzed.[Results] 1) As for the tree planting configuration with the plant spacing was 4 m × 5 m,5 m × 5 m in the study area,the 4-7 years apple trees had mutual shading overlap between apple trees,but no mutual shading overlap occurred between rows.The research about multiple apple trees configuration should focus on apple trees in economic tree and crop intercropping system.2) The crown shading area of the apple tree in north side was always greater than that in the south side.Consequently,planting intercrops at the same distances in north and south side of apple trees was not reasonable in economic tree and crop intercropping system.When designing the row distance of intercrop,we must consider the effect of apple tree crown shading area.In the study,the reasonable intercrop planting distance was determined through analyzing apple-tree crown shading area,repeated shading area,and lasting shading time.3) Because repeated shading area continuously increased with the increase of an apple tree age,which resulted in the competition of solar rays between tree and crop rose with the aging of the tree.While the crown shading area of an apple tree is getting closer to the apple tree,the shading time of the shading area increased.Therefore,the competitiveness for solar rays between tree and crop became growingly significant with the crown shading area was toward to the tree.And the major shading time should be in 9:00-15:00 within a day,and this moment was the important in a day.[Conclusions] Intercrop planting should be determined based on shading area in economic tree and crop intercropping system.And planting area of intercropping is different in economic tree and crop intercropping system with different ages' apple trees.The research provides support about reasonable planting distance of intercrop in economic tree and crop intercropping system.%通过晋西黄土区苹果农林间作系统不同树龄果树的遮阴范围、重复遮阴区域和遮阴时长的研究,遵循平行光线下的相似性原理,将果树按其树体缩小50倍,根据实测苹果树体形状,制作不同林级的苹果树3D模型,利用树体模型在研究区现地进行果树遮阴范围的测定实验.结果表明:1)对于研究区果树种植配置而言,4～7年生果树株间存在遮阴重叠,而行间不存在遮阴重;2)根据对树冠遮阴区域的分析,提出4～7年生果树的合理间作距离;3)随着苹果树树龄的增长,果树与作物的争光明显增强;间作作物距果树越近,果树与作物争光越明显.在果农复合系统中,间作作物的种植应该依据果树遮阴区域而定,并且不同林龄果树的果农复合系统,其间作作物种植区域是不同的.该研究为果农复合系统中,间作作物合理种植间距的确定提供支撑.
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