Elymus nutans is the first domesticated wild forage grass in Tibet. We selected three seed yield indices and seven agronomic traits in an effort to identify correlations between seed yield and agronomic traits of E. nutans‘Baqing’. We sought to identify correlations between seed yield and agronomic traits of E. nutans ‘Baqing’ by principal component analysis, typical correlation analysis, and a stepwise regression method. Correlation analysis revealed that the number of spikes per plant and yield per plant both correlated positively with plant height, number of tillers, and mean flag leaf length (P < 0. 01) with a high degree of significance. Typical correlation analysis revealed that the number of tillers and seed length structure coefficients increased with increases in the combined agronomic trait index variables V1 and V2, indicating that the number of tillers and plant height are the main factors determining seed yield from Plantago lanceolata pendants. Stepwise regression analysis gave highly significant (P < 0. 01) coefficients correlating single plant yield with number of single spikes and average number of grains per spike. The average number of grains per spike was significantly different from the partial correlations between number of single spikes, seed length, average number of nodules, plant height, and average flag leaf length (P < 0. 05). The partial correlation of the number of single spikes with seed length, awn length, and average number of nodules per spike was found to be significantly different (P < 0. 05).

为研究干旱胁迫及SA、GA浸种处理对砂培西藏野生垂穗披碱草种子萌发的影响,对西藏野生垂穗披碱草分别进行4个梯度SA(25、50、75、100 mg/L)、GA(50、75、100、125 mg/L)的浸种处理.浸种24 h后分别在PEG-6000(0、5％、10％、15％、20％)的胁迫下进行砂培发芽试验,在第7天时测定发芽势,第15天测定发芽率、根长等指标.结果表明,PEG胁迫对沙中播种垂穗披碱草种子发芽率呈显著降低趋势(p<0.05).低浓度SA、GA溶液浸种处理可促进垂穗披碱草种子萌发,最适宜浓度分别为50 mg/L、75 mg/L;低浓度SA与全浓度GA浸种处理可有效促进垂穗披碱草根长及芽长的生长.通过隶属函数分析,本试验中可缓解中度及轻度干旱胁迫对砂培垂穗披碱草抑制作用,促进垂穗披碱草种子萌发、根长、芽长生长的最适宜浓度与溶液为75 mg/L GA;重度干旱胁迫(15％、20％PEG-6000)最适宜浓度与溶液分别为125 mg/L GA、50 mg/L GA.

本文基于1961年-2018年四子王旗地面降水和气温日值0.5°×0.5°格点数据集(V2.0),计算该区域23个网格点标准降水蒸散指数(SPEI),并且运用森式斜率法分析了研究区干旱空间分布情况,运用2000年-2018年Modis NDVI数据,利用像元二分法模型计算了植被覆盖度,分析研究区生长季植被覆盖度的变化情况.最后利用相关性分析方法进一步研究干旱和植被覆盖之间的关系.研究表明:(1)四子王旗地区1961年-2018年整体上SPEI为下降趋势,但2000年-2018年在SPEI年际变化上呈现上升趋势,干旱情况有所改善.(2)2000年-2018年生长季植被覆盖度整体上呈现上升趋势.(3)2000年-2018年来SPEI与DNVI呈现较好的正相关关系,63.9％区域SPEI与NDVI呈正相关关系.本文的研究结果表明干旱对植被覆盖情况有较大影响.