磷胁迫下外源乙烯对杉木幼苗生长及磷素利用的影响

Effects of Exogenous Ethylene on Growth and Phosphorus Use Efficiency of Chinese Fir Seedlings under Phosphorus Stress

【目的】验证磷胁迫下添加外源乙烯对杉木幼苗根系生长的促进作用,提高磷素利用率以适应逆境。【方法】选取福建漳平五一国有林场种子园的同一个半同胞家系杉木幼苗作为试验材料,设置不供磷(P_(0):0 mmol·L^(-1)KH_(2)PO_(4))和正常供磷(P1:1 mmol·L^(-1)KH_(2)PO_(4))2个磷水平,在不同供磷水平下设计3个试剂处理(E+:添加200 mg·L^(-1)乙烯利;E-:添加5μmol·L^(-1)乙烯合成抑制剂CoCl_(2);CK:清水),处理30天后用顶空法收集并测定根系组织内乙烯含量,测定杉木幼苗苗高、地径、根系形态、磷素含量与根系皮层细胞溶解率等指标。【结果】1)磷胁迫和外源乙烯均会促进杉木幼苗根系内源乙烯的增加,且在不同供磷水平下E+处理的根系乙烯含量高于其他处理,随着内源乙烯含量的增加,杉木幼苗根系觅磷能力增强,地上部与根系磷素含量均明显增加,磷素利用率提高;2)磷胁迫下,E+处理的苗高增量均明显低于添加乙烯抑制剂处理(E-)和不添加处理(CK),而地径增量则反之;3)E+处理有利于杉木幼苗根长、根平均直径、根体积增量的增长,各指标与根系吸收土壤中有效磷呈正相关关系,促进了杉木幼苗根系对土壤中磷的吸收;4)磷胁迫下,E+处理增加了根系皮层细胞溶解率,且3个处理间达极显著水平,正常供磷环境下差异不显著。【结论】磷胁迫下添加外源乙烯处理的杉木根系乙烯含量与根系形态生长具显著相关关系,杉木地径、根长、根平均直径和根体积明显增加,杉木苗木的磷含量与根系乙烯含量增加,根系皮层细胞溶解率提高。

【Objective】To verify that the addition of exogenous ethylene can promote the root growth of Chinese fir seedlings under phosphorus stress and improve the utilization rate of phosphorus to adapt to adversity.【Method】The seedlings of Chinese fir from No.25 half-sib family cultivated at the seed garden of Wuyi National Forest Farm in Zhangping,Fujian Province,which were selected as experimental materials.Two phosphorus(P)levels of low P supply(P_(0):0 mmol·L^(-1) KH_(2)PO_(4))and normal P supply(P1:1 mmol·L^(-1) KH_(2)PO_(4))were set.Three reagent treatments were designed at different P levels(E+:200 mg/L ethephon,0:no additive reagent,E-:5 mol·L^(-1) ethylene synthesis inhibitor CoCl_(2)).After 30 days of treatment,ethylene in roots was collected by headspace method,and indexes such as seedling height,ground diameter,root morphology,P content and dissolution rate of cortex cells in Chinese fir seedlings were measured.【Result】1)Phosphorus stress and exogenous ethylene both promoted the increase of endogenous ethylene in the roots of Chinese fir seedlings,and the ethylene content in roots treated with exogenous ethylene(E+)was higher than that of other treatments at different phosphorus supply levels,With the increase of endogenous ethylene content,the ability of seeking phosphorus in the roots of Chinese fir seedlings is enhanced,the phosphorus content in the shoots and roots is significantly increased,and the phosphorus utilization rate is improved.2)Under phosphorus stress,the increment of seedling height in the treatment with exogenous ethylene(E+)was significantly lower than that in the treatment with ethylene inhibitor(E-)and the treatment without ethylene inhibitor(CK),while the increment of ground diameter was the opposite.3)The addition of exogenous ethylene treatment(E+)increased the growth of root length,average root diameter and root volume increment of Chinese fir seedlings,and each index was positively correlated with the absorption of available phosphorus in soil by roots,which promoted the absorption of phosphorus in soil by roots of Chinese fir seedlings.4)Under phosphorus stress,the addition of exogenous ethylene treatment(E+)increased the lytic rate of the root cortex,and the three treatments reached an extremely significant level,while the difference was not significant under normal phosphorus supply environment.【Conclusion】Under phosphorus stress,the content of ethylene in roots of Chinese fir treated with exogenous ethylene had a significant correlation with the morphological growth of roots,and the ground diameter,root length,average root diameter and root volume of Chinese fir increased significantly.Under phosphorus stress,the addition of exogenous ethylene increased the phosphorus content and root ethylene content of Chinese fir seedlings and increased the lytic rate of root cortex cells.In order to further reveal the mechanism of exogenous ethylene as the key factor of phosphorus regulation on the growth of Chinese fir seedlings under phosphorus stress.