低磷胁迫对毛竹幼苗生长和养分生理的影响

Effect of low phosphorus stress on growth and nutrient physiology of Phyllostachys edulis seedlings

【目的】探究低磷胁迫对不同生长时期根际土壤养分环境、毛竹Phyllostachys edulis幼苗生长和养分生理的影响及其持续效应,分析毛竹幼苗对低磷胁迫的适应机制。【方法】通过盆栽播种育苗方式,研究了4种不同土壤有效磷水平:2.5 mg·kg^(−1)(极低磷,P_(1))、5.0 mg·kg^(−1)(低磷,P_(2))、10.0 mg·kg^(−1)(中磷,P_(3))、20.0 mg·kg^(−1)(适磷,P_(4))对当年生长季末(T_(1))和翌年快速生长期(T_(2))根际土壤养分环境、毛竹幼苗生物量及其分配、毛竹幼苗养分吸收利用和分配的影响。【结果】低磷处理组(P_(1),P_(2))显著降低T_(1)根际土壤pH(P<0.05),并维持了根际土壤高氮质量分数;这种低磷效应趋势持续至T_(2),且此时P_(1)和P_(2)的根际土壤有机质质量分数较P_(4)显著增加了10.70%(P<0.05)。低磷处理组均显著降低了2个时期毛竹幼苗生物量及氮、磷、钾养分积累量(P<0.05),且T_(2)时的降幅比T_(1)更高。T_(1)时,低磷处理组显著降低了毛竹幼苗根冠比(P<0.05),也相对降低根系养分的分配比例;但T_(2)时,低磷处理组的根冠比分别较P_(4)显著增加44.30%和37.97%(P<0.05),且显著增加了氮、钾养分在根系的分配比例(P<0.05)。低磷处理组显著增加了T_(1)毛竹幼苗整株磷素利用效率(P<0.05),随育苗时间推移,其利用效率下降,至T_(2)时,仅P_(1)较P_(4)显著增加了19.05%(P<0.05)。【结论】低磷胁迫抑制了毛竹幼苗生长和养分积累,但提高了其整体磷素利用效率;随育苗时间延长至翌年快速生长期时,低磷胁迫对植株的抑制作用增强,但毛竹幼苗通过提高根冠比、根系养分分配比例来提高对低磷胁迫的适应性。

[Objective]To explore the effects of low phosphorus(P)stress on rhizosphere soil nutrient environment,as well as the growth and nutrient physiology of Phyllostachys edulis seedlings at different growth stages and their sustained effects,so as to analyze the adaptation mechanism of Ph.edulis seedlings to low P stress.[Method]Seeds of Ph.edulis were sown in pots to cultivate young seedlings.Rhizosphere soil nutrient environment,the biomass and its distribution of Ph.edulis seedlings,and the nutrient absorption,utilization and distribution of Ph.edulis seedlings at the end of the current growing season(T_(1))and the next rapid growing season(T_(2))were determined under four different soil available phosphorus conditions,2.5 mg·kg^(−1)(very low phosphorus,P_(1)),5.0 mg·kg^(−1)(low phosphorus,P_(2)),10.0 mg·kg^(−1)(medium phosphorus,P_(3)),20.0 mg·kg^(−1)(suitable phosphorus,P_(4)).[Result]Low P treatment group(P_(1),P_(2))significantly decreased pH in rhizosphere soil(P<0.05),and maintained the high N content of the rhizosphere soil at T_(1);The low P effect continued to T_(2),and the organic matter content of rhizosphere soil of P_(1) and P_(2) was significantly increased by 10.70% compared with that of P_(4) at this season(P<0.05).Low P treatment group significantly reduced the biomass and the accumulation of N,P,K nutrients of Ph.edulis seedlings at both stages(P<0.05),but the decline at T_(2) was higher than that at T_(1).At T_(1),the low P treatment group significantly reduced the root shoot ratio(R/S)and relatively reduced the proportion ratio of nutrients in the root of Ph.edulis seedlings;However,at T_(2),the R/S of the low P treatment group was significantly increased by 44.30% and 37.97% compared P_(4)(P<0.05),and the distribution ratio of N and K nutrients in the root was also significantly increased.The low P treatment group significantly increased the phosphorus use efficiency(PUE)of the whole plant of Ph.edulis seedlings(P<0.05),the PUE decreased with the passage of seedlings time,only P_(1) significanlty increased by 19.05% compared with P_(4) at T_(2)(P<0.05).[Conclusion]Low P stress inhibited the growth and nutrient accumulation of Ph.edulis seedlings,but increased the overall PUE.With the extension of seedling time to the next rapid growing season,the inhibition effect of low P stress on the plant was enhanced,but the adaptability of Ph.edulis seedlings to low P stress was improved by increasing the root-shoot ratio and the proportion of nutrient distribution to root.