不同水分处理对禾、豆牧草单、混播水分利用特征的影响

Effects of Different Water Treatments on Water Use Feature for Monoculture and Mixed Cropping of Gramineous and Leguminous Forages

为了解禾、豆牧草混播在不同水分处理条件下的水分利用特征,采用盆栽控制试验,研究豆科牧草紫花苜蓿、沙打旺分别与禾本科牧草披碱草混播后在重度水分胁迫处理[T1,45%田间持水量(FC)]、中度水分胁迫处理[T2,55%FC]、正常灌水处理[T3,75%FC]条件下的产量、水分利用效率(WUE)、碳同位素分辨率(Δ^(13)C)及其之间的相关关系。结果表明:T1、T2处理下,单、混播禾、豆牧草的WUE高于T3处理;3种水分处理条件下,沙打旺的WUE均高于紫花苜蓿;T1、T3处理下,紫花苜蓿与披碱草混播组合的WUE均高于紫花苜蓿单播时的WUE,但低于披碱草单播时的WUE;而T3处理下,沙打旺与披碱草混播组合的WUE均高于沙打旺单播时的WUE,低于披碱草单播时的WUE。不同单、混播组合牧草的Δ^(13)C值随土壤含水量的增加而增大;当紫花苜蓿与披碱草混播组合中的豆、禾比为3∶7和7∶3时,各水分处理下紫花苜蓿的Δ^(13)C低于披碱草;而当豆、禾比为5∶5时,T1、T3处理下紫花苜蓿的Δ^(13)C高于披碱草,T2处理下紫花苜蓿的Δ^(13)C与披碱草相同。在重度(T1)和中度(T2)水分胁迫条件下,Δ^(13)C与WUE呈负相关;而在土壤水分量充足的条件(T3)下,Δ^(13)C与WUE为正相关。综上,适度干旱及牧草混播有助于提高牧草的水分利用效率。

In order to understand water use feature of monculture and mixed cropping of leguminous and graminaceous forages under different water treatment conditions,the pot controlled experiment with three water treatments,i.e.severe water stress[T1,45%field capacity(FC)],moderate water stress[T2,55%FC],well watered[T3,75%FC]was used to study the yield,water use efficiency(WUE),carbon isotope resolution(Δ13 C),and the relationship among yield,WUE andΔ13 C was analyzed.The results showed that the WUEs of monocultures and mixed cropping under T1,T2 treatments were higher than those under T3 treatment.The WUE of Astragalus adsurgens was higher than that of Medicago sativa under three water conditions.Under T1 and T3 treatments,WUE of the combinations between Medicago sativa and Elymus dahuricus was higher than that of monoculture of Medicago sativa and lower than that of monoculture of Elymus dahuricus.Under T3 treatments,WUE of the mixtures between Astragalus adsurgens and Elymus dahuricus was higher than that of monoculture of Astragalus adsurgens and lower than that of monoculture of Elymus dahuricus.TheΔ13 C values of monocultures and mixtures increased in line with the increase in irrigation.TheΔ13 C values of Medicago sativa were lower than that of Elymus dahuricus under all the treatments in the sowing combinations with the ratio of leguminous and graminaceous being 3∶7 and 7∶3.However,theΔ13 C values of Medicago sativa were higher than that of Elymus dahuricus under the T1,T3 treatments and same with Elymus dahuricu in combination with the ratio of leguminous and graminaceous being 5∶5 under T2 treatment.The relationship between WUE andΔ13 C was negative under T1 and T2 treatments,and positive under T3 treatment.In summary,moderate water deficit and mixed sowing were helpful to enhance WUE.