水分胁迫逆境处理对水土保持经济树种长山核桃的生理特性的影响

Effects of Water Stress on Physiological Characteristics of Carya illinoensis-an Economical Plant for Soil and Water Conservation

三峡库区消落带冬蓄夏汛水文生态过程形成的典型干湿交替的特殊生态区域环境已引起国内外环境生态研究者的广泛关注.目前,消落带植被的恢复与重建成为库区消落带生态环境治理的重要内容,但评价适生植物的标准还存在较大分歧,特别是对水土保持经济适生树种对干湿交替周期性复杂多变生境的生理生态响应机制更是知之甚少.以长山核桃作为研究对象,研究消落带自然环境条件下长山核桃抗性生理响应机制.揭示长山核桃抗性生理指标的变化规律.借助盆栽模拟试验,模拟干旱和水淹胁迫条件,分析了长山核桃抗性生理和光合作用特征适应机制.研究表明,干旱胁迫对长山核桃的影响最大,持续6天干旱就引起光合和生理生化指标下降,第10天就有植株死亡,第23天植株全部死亡,而间接性淹水处理下的长山核桃全部存活,生长良好.试验过程中生长、光合作用及生理生化指标都和对照组差异不大,说明长山核桃可以适应短期的淹水,持续涝渍胁迫的存活率为87.5%,第20天以后,净光合速率值下降很快,并出现了皮孔增大等适应性性状,表明长山核桃具有耐水淹的特性.

The alternate flooding and drying environment caused by the typical hydro-ecological processes of winter impoundment and summer flooding of the Three Gorges Reservoir has attracted widespread interests from the environmental and ecological researchers.At present,the vegetation restoration and reconstruction of water-level-fluctuating zone becomea major task of the Three Gorges Reservoir ecological environmental management.However,large differences in criterions of how to evaluate pioneer suitable plants are still existing.Specifically,little is known about the physiological and ecological response mechanisms of the pioneer plants to the habitats which have complicated wet-dry alternate cycles.In this study,Carya illinoensis was selected as the researched object.A field plot investigation was conducted to determine its response mechanism to the physiological resistance in natural habitats.Parallel pot experiments,were carried out under laboratory conditions,in order to analyze physiological characteristics of resistance and photosynthetic characteristics of Carya illinoensis.The results show that the drought stress impacted most significantly on Carya illinoensis during the water single factor test.Photosynthetic rate and some indexes decreased when treated for 6-day drought,pecan plants began to die after 10-day treatment,and all plants died on the 23rd day.All of the plants survived and grew well under indirect water treatment during the test.Compared with the control group,the growth,photosynthesis and physiological indexes showed insignificant variations.This indicats that the Carya illinoensis can adapt to short-term flooding.The survival rate of the plant was 87.5% under continuous waterlogging stress.Treated for 20days,The net photosynthetic rateof the plantdropped sharply,and some adaptive traits,such as the increase of lenticel, appeared.These indicate that the pecan has waterlogging toleranceto some extent.