不同磷利用效率杉木在低磷胁迫下的形态及养分分配差异

为充分挖掘植物对低磷胁迫的适应潜力，揭示P高效利用植物对低P逆境的响应机制，选育P高效利用基因型以应对森林土壤有效P匮乏。选择前期研究筛选出的P高效利用杉木M1、M4与P利用效率一般的M24为研究对象，解析不同P利用效率杉木在低P胁迫下的形态及养分分配差异。结果表明，P利用效率一般的M24地上部分生长受低P胁迫的影响大于M1与M4，且地下部的根系增生能力也弱于P高效利用杉木。应对低P胁迫，M1与M4的响应策略也存在差异，其中，M1地上部生长量大，M4地下根系增生能力强，以吸收更多培养介质中的P养分，且更多的物质分配到根系。结合根系解剖结构分析发现，低P胁迫条件下M1表现为高维根比和低皮层比，以加快养分在体内的循环。而M4表现为低维根比和高皮层比，其养分运输能力相对较弱，吸收功能较强。通过不同的策略行为，M1与M4体内的P养分分配表现出一致的规律，二者根系中的P含量均呈现随处理时间延长而逐渐增加的趋势。可见，P高效利用杉木比P利用效率一般的杉木对低P的耐受能力更强，且通过不同的策略适应低P胁迫，其中，M1主要通过加快P养分循环利用的途径增加植株地上部正常生长所需P养分，M4则主要通过根系增生，增加对介质中P养分的吸收，以供地上部生长所需。

Differences in Morphology and Nutrient Distribution of Chinese Fir with Different Phosphorus Use Efficiency under Low Phosphorus Stress

The objectives of this study were to fully tap the adaptation potential of plants to low phosphorus stress,to reveal the response mechanism of plants which can use phosphorus efficiently under low phosphorus stress,and to select the genotypes with highly efficient use of phosphorus to deal with the lack of available phosphorus in forest soil.Two Chinese fir clones (M1 and M4) with high phosphorus use efficiency under low phosphorus stress that were screened out from our previous study and clone M24 with ordinary phosphorus use efficiency were taken as the research objects to examine the morphological and nutrient distribution differences of the clones with different phosphorus use efficiency under low phosphorus stress.The results showed that compared with M1 and M4,the aboveground part growth of M24 was more affected by the low phosphorus stress,and the underground root proliferation ability of M24 was also lower than those of M1 and M4.Differences were also observed in response strategies to low phosphorus stress between M1 and M4:the growth of aboveground part of M1 was higherer than M4,while M4 demonstrated stronger ability for the proliferation of underground root system,so as to absorb more phosphorus nutrients from culture medium and distribute more material to the root system.The root anatomical structure indicated that under low phosphorus stress,M1 showed high v/r ratio and low cortex ratio,thus the circulation of nutrients in plants was speeded up.M4 showed low v/r ratio and high cortical ratio,its nutrient transport capacity was relatively weak,but the absorption ability was stronger.Through different strategic behaviors,the phosphorus nutrient distribution in M1 and M4 was the same,and the phosphorus content in both roots showed a trend of increasing gradually with the treatment time.In conclusion,the clones with high phosphorus use efficiency was more tolerant to low phosphorus than the clone with ordinary phosphorus use efficiency,and the former could adapt to low phosphorus stress through different strategies:M1 increased the phosphorus nutrient needed for normal growth in plant shoot mainly by accelerating phosphorus nutrient recycling,and M4 increased the absorption of phosphorus nutrient in medium through root proliferation,so as to supply the upper growth.