不同磷浓度下马尾松幼苗高生长和光合特征的变化

Variations on the Height Growth and Photosynthetic Characteristics of Pinus massoniana Lamb.Seedlings along a Soil Phosphorus Content Gradient

[目的 ]研究马尾松幼苗在不同磷浓度下的高生长和光合特征响应,揭示马尾松对低磷环境的适应机制,为马尾松林经营管理和精准的生长模拟预测提供试验依据。[方法 ]以两年生马尾松幼苗为试验材料,培养基质以有效磷含量2.325mg·kg^(-1)为对照组(CK),另设无磷(0AP)、 1/8倍磷(1/8AP)、 1/4倍磷(1/4AP)、1/2倍磷(1/2AP)、2倍磷(2AP)和4倍磷(4AP)等磷浓度梯度,经过2021年5月—11月的培养,分析马尾松幼苗高生长和光合特征参数的差异。[结果 ]马尾松幼苗株高的相对生长增量(RHI)和光合参数受到生长时间和磷浓度的影响。5—6月的RHI显著高于7—8月和9—10月,4AP条件下的RHI显著高于1/8AP。株高相对生长速率与磷浓度显著正相关(P<0.05),且随磷浓度的升高而线性增高。净光合速率(Pn)、气孔导度(Gs)、胞间CO_(2)浓度(Ci)和蒸腾速率(Tr)均受到磷浓度、生长时间及其交互作用的显著影响(P<0.05),且各光合参数值均在7—9月最高。Pn和Ci与幼苗RHI显著正相关;生长时间对RHI、Pn、Gs和Ci具有促进作用。[结论 ]马尾松幼苗的高生长和光合特征参数在不同磷浓度下差异显著,马尾松幼苗在低磷环境下通过调节光合作用和高生长动态变化,对低磷环境产生了一定适应机制。

[Objective]To study the response of Pinus massoniana seedlings of height growth and photosynthetic characteristics under different phosphorus concentrations,reveal the adaptation mechanism of P.massoniana to low phosphorus environment,and provide experimental basis for the management and accurate growth simulation prediction of P.massoniana forest.[Method]From May 2021,to November 2021,two-year-old seedlings of P.massoniana were planted in 7 different soil phosphorus concentrations,including control group(2.325 mg·kg^(−1),CK),no phosphorus group(0AP),with an eighth of CK(1/8AP),a quarter of CK(1/4AP),a half of CK(1/2AP),two times of CK(2AP),and four times of CK(4AP);and then the growth and photosynthetic parameters were tested.[Result]Relative height increment(RHI)and photosynthetic parameters of P.massoniana seedlings were affected by growing times and soil phosphorus concentrations.RHI during from May to June(RHI5-6)was higher than that from July to August(RHI7-8)and September to October(RHI9-10).RHI5-6 of 4AP was significantly higher than that of 1/8AP.Relative growth rate of seedlings was positively correlated with soil phosphorus concentrations(P<0.05),and linearly increased with phosphorus concentrations.Net photosynthetic rate(Pn),conductance to H2O(Gs),intercellular CO_(2) concentration(Ci),and transpiration rate(Tr)were significantly affected by soil phosphorus content,growing time and their interaction.And all of them reached their peak in July to September.Pn and Ci were positively correlated with RHI.Growing time had a promoting effect on RHI,Pn,Ci and Gs.[Conclusion]The height growth and photosynthetic parameters of P.massoniana seedlings are significantly affected by soil phosphorus concentrations.P.massoniana seedlings have a special adaptive mechanism to the low-phosphorus environment by regulating photosynthesis and the dynamic changes of height growth.