低磷胁迫对赤皮青冈幼苗叶片生理指标的影响

【目的】探究赤皮青冈幼苗对低磷环境的耐受性。【方法】选取1年生和2年生赤皮青冈Cyclobalanopsis gilva实生幼苗,进行室内控制条件下的低磷胁迫试验,分析赤皮青冈幼苗叶片在低磷胁迫条件下的生理响应情况。【结果】低磷胁迫下1年生、2年生赤皮青冈叶片中可溶性蛋白含量随磷元素浓度降低而下降,膜脂过氧化最终产物丙二醛(MDA)含量上升、体现植株面对胁迫时自我调节的主动响应物质过氧化物酶(POD)、超氧化物歧化酶(SOD)活性明显升高,赤皮青冈内部相应的增加吸收磷能力的酸性磷酸酶(APA)活性升高。特别是POD、SOD和APA含量的变化情况可以间接说明赤皮青冈能通过自身生理调节来适应一定程度的缺磷环境。2年生赤皮青冈幼苗较1年生赤皮青冈幼苗具备更强的抗氧化能力和耐低磷能力,磷利用效率更高。正常情况下,赤皮青冈幼苗低磷耐受浓度为0.01 mmol·L-1,外界环境的有效磷低于该含量就可能会造成幼苗发育不正常或者死亡。【结论】低磷胁迫一方面刺激赤皮青冈叶片产生更多的MDA,进而引起赤皮青冈叶片细胞活性氧自由基代谢失衡;另一方面由于低磷胁迫后赤皮青冈活性氧自由基积聚刺激了保护酶系统的提升,能清除自由基,削弱了膜脂过氧化,进而降低赤皮青冈体内MDA的含量。这两方面形成一种动态平衡是赤皮青冈耐低磷胁迫的主要抗性机制。缺磷的林地进行造林作业时要尽量选取苗龄较大的赤皮青冈幼苗。

Effects of low phosphorus stress on physiological characteristics of Cyclobalanopsis gilva seedling leaves

【Objective】To explore the tolerance of Cyclobalanopsis gilva seedlings to low-phosphorus environment.【Method】The low-phosphorus stress test was carried out on the annual and biennial Cyclobalanopsis gilva seedlings by hydroponic culture which can control the single factor of phosphorus concentration, and the physiological response of Cyclobalanopsis gilva under low phosphorus stress was analyzed.【Result】In low phosphorus stress, the changing trend of soluble protein content in Cyclobalanopsis gilva leaves of annual and biennial consistent with phosphorus concentration. With the increase of the low-phosphorus stress level and prolonged stress time, the MDA content increased, and the activities of POD, SOD, APA also increased. This finding indicated that Cyclobalanopsis gilva can adapt to a certain degree of phosphorus deficiency environment through its physiological regulation. According to the comprehensive test data, the biennial Cyclobalanopsis gilva seedlings have stronger photosynthetic capacity, antioxidant capacity and phosphorus utilization efficiency than the annual Cyclobalanopsis gilva seedlings, and have strong ability to resist low phosphorus. We also found that the lowest phosphorus tolerance concentration of Cyclobalanopsis gilva seedlings was 0.01 mmol·L-1, otherwise it may cause abnormal growth of seedlings or death.【Conclusion】On the one hand, low phosphorus stress can stimulate more MDA production in leaves of Cyclobalanopsis gilva, and then lead to imbalance of active oxygen free radical metabolism in leaves of Cyclobalanopsis gilva. On the other hand, the accumulation of reactive oxygen species stimulated the protective enzyme system under low phosphorus stress, which could scavenge the reactive oxygen species and weaken the Membrane Lipid peroxidation, thus reducing the content of MDA in Cyclobalanopsis gilva. These two aspects form a kind of dynamic equilibrium, which is the main resistance mechanism of Cyclobalanopsis gilva to low phosphorus stress. The results of this experiment have certain reference value for selecting seedling age of transplanted Cyclobalanopsis gilva seedlings in regions with phosphorus deficiency.