苜蓿——禾草混播草地牧草产量及种间竞争关系的动态研究北大核心CSCD

为了解在内蒙古中部轻度盐碱地上建植豆禾混播草地的牧草产量及各混播组合物种的竞争关系,以草原3号苜蓿分别与新麦草、缘毛雀麦和长穗偃麦草3种禾草以不同比例(1∶1,1∶2,1∶3)混播建植人工草地,研究不同刈割期、不同混播方式下的牧草产量、土地当量比(LER)、相对产量(RY)、相对密度(RD)、相对产量总值(RYT)和种间竞争率(CR)等。结果表明,混播物种、混播比例和刈割时期对混播草地的产量和种间竞争关系有直接影响。在3个刈割时期,所有混播组合的牧草产量均高于单播,且土地当量比均大于1。相对产量、相对密度和相对产量总值除个别1∶3组合外也均大于1,根据物种竞争模型对混播组合中各物种竞争关系进行分析,发现除豆禾1∶3组合外,苜蓿与3种禾草均分布在双方受益区域,表明各草种混播组合基本呈共存状态。除苜蓿与缘毛雀麦1∶1组合外,苜蓿在其余各混播组合中种间竞争率均大于1,且在同一刈割期随禾草比例的升高而增大。从牧草产量和种间关系的稳定性综合考虑,在上述地区苜蓿与缘毛雀麦以1∶1或1∶3混播,苜蓿与新麦草、苜蓿与长穗偃麦草以1∶1或1∶2混播更有利于建立高产稳定的人工草地。

The dynamic analysis of forage yield and interspecific competition in alfalfa-grass mixed pasture

Legume-grass mixed pastures were established on slightly alkaline soil in central Inner Mongolia， China. Three different grass species （Psathyrostachys juncea， Bromus ciliatus and Elytrigia elongata） were each sown with the alfalfa cultivar Caoyuan No.3 （Medicago varia） in legume∶grass ratios of 1∶1， 1∶2 or 1∶3. These 4 species were chosen because trial plantings in the area had confirmed they are suited to the local climate. Three years after the mixtures were established， the forage yield， land equivalent ratio （LER）， relative forage yield （RY）， relative density （RD）， relative total yield （RYT）， and inter-species competition rate （CR） were evaluated for three different growth periods during the summer. It was found that the forage yield of all mixed sowing combinations was much higher than single species stands at all three harvest dates. Hence the LER of all mixed sowing combinations was greater than 1. RY， RD and RYT also exceeded 1 in most combinations， with the exception of two of the mixtures sown at the 1∶3 ratio. The competition relationship within the different mixtures was also analyzed. When alfalfa mixtures with the three grass species were established at 1∶1 and 1∶2 ratios， there was stable coexistence with benefits distributed to both species in the mixture， and the CR between legume and grass was predominantly greater than 1 （except for the alfalfa-B. ciliatus combination sown at 1∶1） and tended to increase as the proportion of grass in the mixture was increased. Considering both the productivity and stability of the pasture mixtures， an alfalfa-B. ciliatus mixture sown at a 1∶1 or 1∶3 ratio， or alfalfa-E. elongata or alfalfa-P. juncea mixtures established at 1∶1 or 1∶2 ratios were most conducive to the establishment of high-productivity and stable artificial grassland in this area.