Abstract:
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 CO2 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.
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