Abstract:

This research aimed to identify the optimal mixed sowing pattern for grass-legume mixes in Horqin Sandy Land. Alfalfa （Medicago sativa） was sown into 2-month-old smooth bromegrass （Bromus inermis） in two patterns （inter-row sowing， A₁， and crossed row sowing， A₂） at eight mixed sowing ratios （5%， 10%， 15%， 20%， 25%， 30%， 35% and 40%， calculated based on single plant density； Treatments B₁-B₈， respectively）. Three cuts were made during the growing season and bromegrass yield， alfalfa yield， and total herbage yield were determined for each cut and on an annual basis. Comparing sowing patterns A₁ and A₂， grass yield and legume yield differed only in Cut 3， with A₂>A₁ for grass yield and A₁>A₂ for legume yield while for combined grass+legume yield there was a significant difference （P<0.05） for all three cuts and in the annual total with A₁>A₂ in all cases. Across the mixed sowing ratios B₁-B₈， alfalfa and total herbage yield increased， while smooth bromegrass yield decreased （P<0.05）. With respect to relative density （RD）， grass RD was significantly higher （P<0.05） in the A₂ than the A₁ sowing pattern in Cuts 2 and 3， but legume RD did not differ between A₁ and A₂ sowing patterns in any of the three cuts. Across the mixed sowing ratios B₁-B₈， RD generally decreased for grasses in cuts 2 and 3 and for the legume component in all three cuts （P<0.05）. The relative yield （RY） differed between A₁ and A₂ sowing patterns for bromegrass only in Cut 3 （A₂>A₁） and for alfalfa only for the annual total （A₁>A₂； P<0.05）. For both bromegrass and alfalfa， RY decreased （P<0.05） across the mixture ratio series from B₁ to B₈ for all three cuts， and for the annual total. The results of fuzzy multivariateanalysis showed that the A₂B₄ combination was the best， followed by the A₂B₃ combination. Considering forage yield and stability of the sown mixture， the recommended practice based on these data is cross-sowing alfalfa into 2-month-old smooth bromegrass stands at a plant density of 15%-20% of the grass single-plant sowing rate.

Key words: grass-legume mixture, forage yield, interspecific compatibility, community stability, fuzzy comprehensive evaluation