宁夏中部半干旱带不同灌溉量下的禾豆混播效果

以紫花苜蓿(Medicago sativa)和沙打旺(Astragalus adsurgens)两种豆科牧草与无芒雀麦(Bromus inermis)、披碱草(Elymus dahuricus)、扁穗冰草(Agropyron cristatum)3种禾本科牧草为材料,在宁夏中部半干旱地区开展禾本科和豆科牧草单播及禾豆混播试验,设置3种水分梯度处理,即低灌溉量(484 mm)、中灌溉量(707 mm)、高灌溉量(1 160mm),对不同水分处理条件下单混播组合的产量、整株的碳同位素分辨率(Δ~(13)C)及光合作用参数等生理指标进行测定分析。结果表明,在宁夏中部干旱带有灌溉条件下进行禾豆牧草混播可以提高群体的产量和水分利用效率,其中沙打旺+披碱草混播组合产量及水分利用效率表现最好且Δ~(13)C值最高。不同水分处理对禾、豆牧草的株高、光合生理参数、产量及Δ~(13)C等有显著影响(P0.05)。牧草混播组合在高灌溉量时的产量、水分利用效率(WUE)及Δ~(13)C最高,低灌溉量条件下最低。在高灌溉量时Δ~(13)C、气孔导度(Gs)、叶温、株高等与产量和WUE的关系最为密切。因此,在高灌溉量时可将高Δ~(13)C作为筛选高产组合的标准,在低灌溉量时可将低Δ~(13)C作为筛选抗旱节水组合的理想指标。

Effect of mixed sowing of graminaceous and leguminous forages under different water regimes in Ningxia central semi-arid belt

Two leguminous forages (Medicago sativa and Astragalus adsurgens) and three graminaceous forages (Bromus inermis,Elymus dahuricus,and Agropyron cristatum) were sown separately and in six combinations in Ningxia central semi-arid belt under three water treatments,i.e.low irrigation (484 mm),intermediate irrigation (707 mm),and high irrigation (1 160 mm).Yield,the whole plant △13C,and photosynthetic exchange parameters were determined.The results showed that mixed sowing of graminaceous and leguminous forages could improve yield and water use efficiency (WUE) in central Ningxia when irrigated.Among the different combinations that were sowed,the highest △13C,yield,and WUE were recorded when Astragalus adsurgens was combined with Elymus dahuricus.There was a significant effect of water treatment on the plant height,photosynthetic physiological parameters,yield,and △13C of graminaceous and leguminous forages (P＜0.05).The values of yield,WUE,and △13C were the highest in high irrigation treatmentand the lowest in low irrigation treatment.Yield and WUE were found to correlate significantly with △13 C,leaf stomatal conductance (Gs),leaf temperature,and plant height in high irrigation treatment and in low irrigation treatment.The former can be used as an alternative selection indicator for screening high-yield combinations and the latter can be used as an alternative selection indicator for screening water-saving combinations.