混播比例及播种方式对老芒麦与紫花苜蓿混播系统生产力及种间关系的影响

Effect of mixed planting ratio and planting method onthe productivity and interspecific relationship ofElymus sibiricus and alfalfa in mixed planting system

摘要:

以不同播种比例(2∶1、5∶2、3∶1、7∶2和4∶1,分别用1,2,3,4,5表示)及播种方式(间行和同行,以A、B表示)下的老芒麦(Elymus sibiricus)和根茎型清水紫花苜蓿(Medicago sativa cv.Qingshui)混播系统为研究对象,对建植第2年混播草地草产量、相对密度(RD)、相对产量(RY)、相对产量总值(RYT)及竞争率(CR)进行研究,通过灰色关联度分析揭示混播比例及播种方式对种间关系的影响,进而确定黄土高原区老芒麦和紫花苜蓿混播的最适混播比例及播种方式。结果表明:混播草地的年草产量在豆禾比1∶2同行混播组合下最高。RYT无论第1茬还是第2茬均以 A3组合最高且RYT＞1,混播的两种牧草在一定程度上避免了竞争,存在生态位分离。灰色关联度分析得豆禾比1∶2同行混播下紫花苜蓿的综合种群优势较好;豆禾比1∶4间行混播下老芒麦综合种群优势较好。在黄土高原区紫花苜蓿和老芒麦1∶2同行混播较适宜。

Abstract:

This study investigated the effect of mixed planting ratio and planting method on the productivity and interspecific relationship of Elymus sibiricus and alfalfa in mixed planting system.The experiments included different planting ratios of E.sibiricus and alfalfa (2∶1,5∶2,3∶1,7∶2 and 4∶1,denoted by 1,2,3,4 and 5) and planting methods (inter line and same line,denoted by A,B).The number of branches/tillers,grass yield,relative density (RD),relative yield of population (RY),relative yield total (RYT) and interspecific competition rate (CR) of mixed grassland in the second year of establishment were measured.The influence of mixed seeding ratio and seeding method on the inter-species relationship was analyzed using gray correlation analysis.Furthermore,the optimal mixed planting ratio and planting method for mixed planting of E.sibiricus and alfalfa in the Loess Plateau were determined.The results showed that the annual grass yield of mixed grassland was the highest under treatment B1.For both the first cutting or the second cutting,the RYT was the highest in A3 (RYT＞1).The gray correlation analysis showed that the comprehensive population advantage of alfalfa was better under the alfalfa and E.sibiricus ratio of 1:2 than other ratios;the comprehensive population advantage of E.sibiricus was better with the E.sibiricus and alfalfa ratio of 1:4.The results suggest that the two mixed forages could avoid competition to a certain extent,and there could be niche separation.The results also showed that the competitiveness of alfalfa gradually decreased after the first mowing,and the competitiveness of E.sibiricus gradually increased.The optimal treatment was intercropping mixture with the alfalfa to E.sibiricus ratio of 1∶2 in the inter line.