海水胁迫下冰草幼苗期耐盐性指标筛选

冰草植物为禾本科小麦族多年生牧草，具有耐干旱、抗寒冷、耐盐碱等优点，是盐碱地改良的优良作物。为给冰草种质耐盐性评价提供依据，本试验对2个冰草主栽品种，蒙农1号蒙古冰草和蒙农杂种冰草，通过温室花盆培育在幼苗期进行了5个海水浓度的梯度胁迫，经30 d胁迫后，对各浓度处理材料的株高(SH)、根长(RL)、超氧化物歧化酶(SOD)、丙二醛(MDA)和K⁺等共12项农艺性状和生理指标进行了测定。探究盐胁迫对冰草幼苗的生长特征、K⁺/Na⁺、抗氧化酶活性和渗透调节物质等的影响；通过公式计算各项指标在不同浓度海水处理下的耐盐系数，进一步对其采用主成分分析、模糊隶属函数分析和逐步回归方程等方法进行耐盐性系统评价。结果表明：供试材料在不同浓度盐胁迫处理下除苗相对含水量无显著差异外，各指标间均存在显著差异(P<0.05)；利用主成分分析法筛选得到了10项可对冰草种质材料幼苗期进行耐盐性鉴定的指标；总结出3个盐胁迫因子，分别为渗透调节因子、株型因子、根系因子；利用逐步回归方程方法得出了可用于冰草种质材料耐盐性预测的回归模型，D=0.83...

Comprehensive screening of Agropyron cultivars for tolerance to salt stress at the seedling stage

Agropyron is a perennial grass in the Triticeae （Poaceae）. It has the advantages of resistance to drought， cold， and salinity， so it is an excellent crop for saline-alkali land improvement. To provide a basis for the evaluation of salt tolerance of Agropyron， seedlings of two main Agropyron cultivars， Agropyron mongolicum cv. Mengnong No.1 and Agropyron cristatum×Agropyron desertorum cv. Hycrest-Mengnong， were exposed to salinity stress using five concentrations of seawater in a pot experiment in a greenhouse. Thirty days later， twelve indexes were investigated including root length （RL）， shoot height， superoxide dismutase （SOD） activity， malondialdehyde content，^{and K+ content. The effects of salt stress on the seedling growth characteristics， K+/Na+， antioxidant enzyme activity， and contents of osmotic regulatory substances in the Agropyron materials were analyzed. The saline tolerance coefficient of each index under different seawater treatments was calculated， and then the salt tolerance of Agropyron at the seedling stage was comprehensively analyzed by a principal components analysis， subordinate function analysis， and regression analysis. All of the indexes except for the relative water content of the shoot showed significant differences （P<0.05） among the different salt stress treatments. A principal components analysis was conducted using ten indexes to evaluate the salt tolerance of the Agropyron at the seedling stage. A regression analysis identified three important factors in salt stress tolerance： An osmotic adjustment factor， a plant type factor， and a root system factor. The following mathematical evaluation model for Agropyron salt tolerance was established by regression analysis： D=0.833-0.018SOD-0.147SP-0.042SS-0.142Pro-0.004Na+-0.520 K+-0.076RL， where SP=soluble protein， SS=soluble sugars and Pro=proline. Using this equation， the salt tolerance of Agropyron germplasm resources could be quickly and accurately predicted on the basis of seven indexes： SOD， K+， Na+， SP， SS， Pro， and RL. These analyses revealed that the salt tolerance of Hycrest-Mengnong was higher than that of Mengnong No.1. The results of this study will be useful for promoting and managing the cultivation of grasses in salinized areas.}