Effects Of Apple/White Clover Intercropping System On Apple Photosynthate Distribution Patterns And Root Respiration

The interspecific relationship is the core issue in the study of living mulch.However,there was still research gaps in the study of the internal mechanism on the developmental effects caused by living mulch,especially the interaction of underground part.So based on root box cultivation experiment and ¹³C stable isotope pulse labeling experiment,this paper studied the effects of intercropping with white clover on intercropped apple development pattern and root morphology through chemical composition,photosynthate distribution andrespiration of apple roots to explore the internal mechanism caused by white clover intercropping on affecting tree development and root morphology change.The main conclusions are as follows:?1?White clover intercropping significantly inhibited the growth of young apples,and reduced the biomass of intercropped apples by 33.50%at the deciduous stage after intercropping for one year.Among them,white clover intercropping had the most obvious inhibition on the aboveground part,with a decrease of 37.64%in biomass,but it significantly promoted the growth of root system in the underground part of apple trees during autumn shoot growth period,with the increased biomass by 17.56%.?2?Intercropping white clover significantly changed the root morphology and distribution of apple trees,made the roots of young apples develop towards the soil below 20 cm soil layer,and promoted the further development of fine roots with a diameter of 0-1 mm and the development of thick roots with a diameter of>4 mm to occupy a larger soil volume than monoculture apple trees.?3?Intercropping white clover significantly changed the distribution pattern of Apple Photosynthate in the intercropping system.During the autumn shoot growth period,more photosynthates were distributed to the underground roots,mainly to the roots below 20 cm soil layer and the fine roots with a diameter of 0-1 mm.This phenomenon was most obvious after the third day of marking.?4?Intercropping white clover also increased the respiration rate and nitrogen content of fine roots with diameter of 0-1 mm,and increased the cellulose content and decreased the lignin content of root system.?5?Unlike the general understanding,the effect of white clover intercropping on apple is not only by changing its external soil nutrients and other environmental factors,but also by changing the development pattern of apple trees,making it develop roots preferentially at the cost of inhibiting the development of aboveground parts in young age,supplying more photosynthates and other nutrients to roots,thus changing root morphology,root metabolism and root structure enable roots to occupy a larger soil volume faster,so as to achieve advantages in competition with white clover,and ultimately achieve the effects of biomass,stress resistance and yield improvement.