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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (2): 159-170.DOI: 10.11686/cyxb2021175

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A study of yield interactions in mixed sowings of alfalfa and three perennial grasses

Hui-hui ZHANG(), Shang-li SHI(), Bei WU, Zi-li LI, Xiao-long LI   

  1. Pratacultural College,Gansu Agricultural University,Key Laboratory of Grassland Ecosystem of Ministry of Education,Sino-U. S. Centers for Grazing Land Ecosystem Sustainability,Lanzhou 730070,China
  • Received:2021-05-06 Revised:2021-06-30 Online:2022-02-20 Published:2021-12-22
  • Contact: Shang-li SHI


This study investigated the yield and competitive interactions in three mixed-sown combinations of alfalfa (Medicago sativa) and a perennial grass (M. sativa+Poa pratensisM. sativa+Bromus inermis and M. sativa+Festuca arundinacea). The mixtures were established at legume∶grass ratios of 7∶3, 5∶5, and 3∶7, and monocultures of alfalfa and the three grasses were also included as a contrast. Data on biomass and key morphological traits of each species in the various monocultures and mixed sowings were collated and analyzed to investigate the competitive interactions between alfalfa and the three grass species, so as to provide a theoretical basis for the development of management guidelines for high yield and high quality of mixed sown pasture. Results indicated that the relative yield (RY) values of alfalfa in the three mixed sowing combinations were higher than 1.0 and that alfalfa had a competitive advantage over the grasses. The growth of the grass in the combinations of M. sativa+P. pratensis and M. sativa+B. inermis was suppressed by alfalfa, while grass in M. sativa+F. arundinacea combination grew synergistically with alfalfa. For the three legume∶grass ratios tested in the mixed-sown plots, the RY for the alfalfa component ranked 3∶7>5∶5>7∶3 and RY for the grass component ranked 3∶7>7∶3>5∶5. For the alfalfa component, responses to the mixed sowing systems included reduced plant height and increased stem diameter and leaf area. For the grass component, plant height increased and stem diameter reduced were also observed but leaf area was increased in mild competition and decreased in more intense competition. These responses resulted in a high (>1.0) total relative yield (RYT) value under different mixed sowing ratios. The species in the mixed sown plots adapted to the variations in the interspecific relationship by adjusting their morphological characteristics, and these adjustments provided the mechanism for the achievement of synergistic growth and yield increase. Among the three mixed sown combinations, M. sativa+F. arundinacea exhibited a greater biomass-increasing effect than the others, especially with the legume:grass ratio of 3∶7. In contrast, in the mixed sowings of M. sativa+P. pratensis and M. sativa+B. inermis, the legume∶grass ratio of 7∶3 had the highest biomass-increasing effect.

Key words: alfalfa, perennial grasses, mixed sowing, interspecific competition, morphological character, forage yield