为了解干旱胁迫对马尾松幼苗生长、生理及光合特性的影响,揭示不同抗旱时期马尾松幼苗中各种物质含量的变化规律及抗旱机制,以1年生马尾松幼苗为试材,采用温室土培盆栽进行干旱胁迫处理,对胁迫0、15、30、45、60天的马尾松幼苗分别测定相关生理生化及光合特性指标。结果表明,随干旱胁迫程度加剧和胁迫时间延长,马尾松幼苗根冠比略上升,严重胁迫下苗高生长量、地径生长量及干物质积累,比正常浇水(CK)分别降低了69.89%、70.73%、75.58%;马尾松幼苗中的过氧化物歧化酶、过氧化物酶的活性呈先升后降趋势,处理30天时中等和严重胁迫处理均达峰值699.81、817.82 U/g,比正常供水分别上升75.57%、104.01%;45天时过氧化物歧化酶的活性仍较高,而严重胁迫下过氧化物酶活性达峰值319.00 U/(g·min),比正常浇水分别高171.88%,与正常浇水呈显著性差异;丙二醛、脯氨酸含量逐渐上升;生长指标根冠比与生理指标丙二醛、蒸腾速率、茎生物量、气孔导度之间,气孔导度与根生物量均呈很强的正相关(r=1);但脯氨酸与净光合速率呈显著负相关(r=-1)。马尾松幼苗通过调整生长和生物量分配抵御干旱胁迫;水分亏缺引起马尾松幼苗蒸腾作用和光合作用减弱;干旱初期通过快速增加抗氧化性酶活性保护幼苗过氧化伤害,中后期则增加渗透调节物质,维持细胞内渗透压缓解膜质损伤;马尾松通过调整光合及相关生理机制,制约与协调不同组织应对干旱胁迫。

The effect of drought on photosynthesis and physiological response of Pinus massoniana seedlings and the underlying mechanisms were investigated. One-year-old P. massoniana seedlings were used as materials, and greenhouse soil potting was used to carry out drought stress treatment. After treatment for 0, 15, 30, 45 and 60 days, some indexes were determined to study the effects of continuous drought on the growth of P. massoniana seedlings. The results showed that with the intensification of drought stress degree and the extension of stress time, the seedling root-shoot ratio increased slightly. Under severe stress, the seedling height growth, ground diameter growth and dry matter accumulation decreased by 69.89%, 70.73% and 75.58%, respectively. The activity of peroxides dismutase and peroxidase in P. massoniana seedlings increased at first and then decreased, and reached the peak values of 699.81 and 817.82 U/g, until thirtieth day of medium and severe stress, which increased by 75.57% and 104.01% than normal water supply. At 45 ^th day, the activity of peroxidase was still high, under severe stress, while the peroxidase content reached a peak of 319.00 U/(g·min), which was 171.88% higher than that of normal watering and showed a significant difference from normal watering. The content of malondialdehyde and proline increased gradually. The index of root-shoot ratio and physiological indicators of malondialdehyde, transpiration rate, stem biomass, stomatal conductance, stomatal conductance and root biomass showed a strong positive correlation (r=1); however, proline had a strong negative correlation with net photosynthetic rate (r=-1). P. massoniana seedlings resisted drought stress by adjusting growth and biomass distribution. Transpiration and photosynthesis were weakened by water deficit. In the early stage of drought, antioxidant enzyme activity was rapidly increased to protect the peroxidation damage of seedlings. In the middle and later stages, osmotic substances were added to maintain the osmotic pressure in cells to alleviate the membrane damage. P. massoniana restricted and coordinated various tissues and organs to deal with drought stress by adjusting photosynthesis and the related physiological mechanism.