供磷水平对不同杉木无性系根系细胞壁果胶含量、形态生长及磷效率的影响OA

[Objective]This study aimed to explore the difference of pectin content,morphological growth and phosphorus use efficiency(PUE)of root cell wall of Chinese fir(Cunninghamia lanceolata)clones un-der low phosphorus(P)stress,and to reveal the intrinsic mechanisms underlying their tolerance to low P conditions.[Methods]Based on One-year-old seedlings of five cutting propagated Chinese fir clones(No.7,11,27,36,and 41),three P application levels were established:severe P stress(no P application),middle P stress(0.5 mmol·L-1 KH2PO4),and control group(1.0 mmol·L-1 KH2PO4,normal P application).Root cell wall pectin content,seedling morphological growth indices,P accumulation,and PUE were meas-ured under each treatment to explore the intrinsic relationship between changes in root cell wall pectin con-tent and PUE of Chinese fir under low P stress.[Results](1)Under the control treatment,the pectin con-tent in the root cell walls of the five Chinese fir clones ranged from 4.07 to 5.37 mg·g-1.With decreasing P supply,the variation patterns of pectin content differed significantly among clones.Under both severe and moderate P stress,the root cell wall pectin content of clones No.11,No.27 and No.41 increased signific-antly,whereas that of clone No.7 decreased significantly.(2)Morphological growth differed among Chinese fir clones.Under moderate P stress,the root collar diameter increment of clone No.41 was signi-ficantly greater than that of clones No.7,No.11 and No.36.Under severe P stress,clone No.7 exhibited the greatest seedling height increment,reaching 6.81±0.36 cm.In addition,the root surface area increment of(197.22±75.41 cm2)and volume(4.05±0.23 cm3)of clone No.7 under severe P stress were significantly higher than those of other clones.(3)Under both moderate and severe P stress,all five Chinese fir clones adapted to low P stress by improving root PUE.Among them,clone No.7 increased significantly by 107.25％compared with normal P application under severe P stress,and the increase was greater than that of other clone,followed by clone No.36.(4)Redundancy analysis showed that root cell-wall pectin sig-nificantly affected PUE in Chinese fir(F=5.17,p=0.012).Combined with the correlation analysis results,the relationship between root cell wall pectin and PUE was influenced by clone and P application level.[Conclusion]Different Chinese fir clones adopted distinct adaptive strategies in response to low P stress.Compared with the other clones,clone No.7 promoted the improvement of PUE while reducing the pectin content in root cell wall,suggesting that it may possess a more efficient low-P adaptation strategy.