9种豆科饲草越冬性能对晚播期的响应

Responses of overwintering performance of nine legumes to a late sowing date

以中国北方9种豆科饲草为试验材料,在7月15日至8月25日间5个播期下,检测了9种豆科饲草越冬前形态和生理特征及越冬率。结果表明,播期延后显著降低越冬前各豆科饲草株高、叶片数量、根颈直径、主根长度、地上和根生物量、根系可溶性糖和总氮含量,增加地上生物量/根系生物量比值。与播期7月15日相比,7月25日、8月5日、8月15日、8月25日播期下,豆科饲草平均越冬率分别降低了35%、56%、91%和96%。由于越冬前根系生物量分配及根系可溶性糖和氮素含量更高,龙牧801苜蓿(Melilotoides ruthenicus×Medicago sativa‘Longmu No.801’)、扁蓿豆(Medicago ruthenica)、沙打旺(Astragalus adsurgens)和兴安胡枝子(Lespedeza daurica)的越冬性能明显优于其他豆科饲草。基于本研究结果和草地管理实践,建议松嫩平原天然割草地在8月5日前后进行豆科补播;从越冬性能考虑,龙牧801苜蓿、扁蓿豆、沙打旺和兴安胡枝子是补播优选植物;为促进补播豆科植物建植,建议将补播当年草地割草时间从传统的8月中旬适当提前。

Nine native and bred legume forages from northern China were selected as experimental materials.Under five sowing dates between 15 July and 25 August,the plant morphological and physiological features before overwintering,and overwintering rate of nine legumes were examined.The results showed that the delayed sowing date significantly decreased the plant height,leaf number,root collar diameter,main root length,above-ground and root biomass,and soluble sugar and nitrogen concentrations of the root,but increased the above-ground biomass/root biomass for the nine legumes.A sowing date of 25 July,5 August,15 August,and 25 August led to a mean overwintering rate of the nine legumes that was lower by 35%,56%,91%,and 96%,respectively,than that for a sowing date of 15 July.Melilotoides ruthenicus×Medicago sativa Longmu No.801,Medicago ruthenica,Astragalus adsurgens,and Lespedeza daurica had better overwintering performance than did the other legume forages,which was attributed to their higher root biomass allocation,soluble sugar,and nitrogen concentrations in their roots before overwintering.Based on our study results and grassland management practices,it is suggested that legume reseeding should be carried out on 5 August in the native mowing pastures of Songnen Plain;M.ruthenicus×M.sativa Longmu No.801,M.ruthenica,A.adsurgens,and L.daurica should be recommend for use as reseeded legumes based on their overwintering performance.To promote establishment of reseeded legumes,the mowing of grasslands should be carried out earlier than its usual time of mid-August.