保水剂用量对胡杨幼苗生长、光合特性和抗逆生理的影响

  目的  探究极端干旱区保水剂对荒漠植物生长与生理特性的影响，明确荒漠植物生长所需适宜保水剂用量，促进抗旱保墒造林技术在干旱荒漠区生态恢复中的应用。  方法  以胡杨2年生幼苗为研究对象，通过田间干旱试验研究5个聚天冬氨酸（PASP）保水剂用量（0、5、10、15、20 g/株）对胡杨幼苗生长、光合特性、生物量分配和抗逆生理指标的影响，并对其影响效果进行综合评价。  结果  （1） 干旱胁迫条件下，根施PASP保水剂可提高胡杨幼苗根际土壤含水量并改善幼苗体内水分状况，增加幼苗株高、地径、新梢生长量、光合器官总量、侧根数量及生长速率，显著促进枝叶生长。（2） 根施PASP有效拓宽胡杨幼苗光照生态幅，提高气孔导度、胞间CO₂浓度和光能、水分利用率，降低呼吸消耗，显著提升光合能力和资源利用效率。（3） 根施PASP有效促进胡杨幼苗地上、地下部生物量积累，改变了生物量分配比例，降低了根冠比，显著提高幼苗生物量。（4） 根施PASP显著增加胡杨幼苗叶片可溶性蛋白、可溶性糖含量，提高超氧化物歧化酶和过氧化物酶活性，降低丙二醛含量，提升幼苗渗透调节和抗氧化能力。（5） 利用主成分分析和隶属函数综合评价表明，保水抗旱促生长效果依次为:10 g/株 > 15 g/株 > 20 g/株 > 5 g/株 > CK。  结论  在干旱区节水抗旱造林实践中胡杨幼苗最适PASP用量为10 g/株，研究为极端干旱荒漠区植被恢复提供了科学依据与参考。 

Effects of super absorbent polymer dosage on growth,photosynthetic characteristics and stress-resistance physiology of Populus euphratica seedlings

  Objective  This study examined the effects of polyaspartic acid (PASP) dosages on the growth and physiological characteristics of desert plants under drought stress condition, and further to ascertain the suitable PASP dosage for plant growth, aiming to promote the application of drought-relief and moisture-conserving technology for ecological restoration in extreme arid area.  Method  Two-year-old P. euphratica seedlings were selected as the research object, a field drought experiment was conducted to study the growth, photosynthetic characteristics and drought-resistance physiology of P. euphratica seedlings under different PASP application regimes, and a comprehensive evaluation on their impact efficiency was drawn out.   Result  (1) Under drought stress condition, root application PASP could enhance the rhizosphere soil moisture and improve the water status of seedlings, and increase the plant height, ground diameter, increment of new shoot, number of photosynthetic organs and lateral roots, and growth rate, to significantly facilitate the growth of branches and leaves. (2) Root application PASP effectively widened light ecological amplitude, and increased stomatal conductance, intercellular CO₂ concentration, light energy and water use efficiency, and reduced respiratory consumption, to significantly improve photosynthetic capacity and resource use efficiency of seedlings. (3) Root application PASP effectively promoted the aboveground and underground biomass accumulation, and changed the biomass allocation ratio, and decreased the root shoot ratio, to significantly increase the seedling biomass. (4) Root application PASP significantly increased the concentrations of soluble protein, soluble sugar, and increased the enzyme activity of superoxide dismutase, peroxidase, and decreased the content of malondialdehyde. It strengthened the osmotic regulation and antioxidant capacity of seedlings. (5) A principal component analysis and multivariate data evaluation indicated that the water-retention and growth promotion effect of different PASP dosages were in the order of 10 g/plant > 15 g/plant > 20 g/plant > 5 g/plant > CK.   Conclusion  In the practice of water-saving and drought-resistant afforestation in arid areas, the most suitable PASP dosage of P. euphratica seedlings is 10 g/plant, which provides scientific basis and reference for vegetation restoration in extremely arid desert areas.