Effect of mixed pattern on growth efficiency and mixed advantage of Bromus innermis+Onobrychis viciaefolia mixture pasture

This study aimed to determine the relative growth efficiency and interspecific competition dynamics of two kinds of forage grass (Bromus inermis and Onobrychis viciaefolia) under different mixed modes (i.e., alternating rows and peer-mixed seeding patterns). A pot experiment was performed to analyse and compare the relative growth rates, chlorophyll fluorescence parameters, herbage yields, and relative yields (RY) of the grasses. The results showed that the relative growth rates of both grasses were higher with mixed seeding than with monocropping, and using a spacing of 30 cm between rows for the alternating rows mixed seeding pattern yielded the highest relative growth rates among the tested treatments. The relative density of B. innermis (RDg) and the relative density of O. viciaefolia (RDl) under the alternating rows mixed seeding pattern were both higher than that in the peer-mixed seeding pattern. A spacing of 30 cm between alternating rows yielded higher RDl and RY values of O. viciaefolia, while peer-mixed seeding or a spacing of 30 cm between alternating rows yielded a higher RYT (total relative yield) value. The initial fluorescence efficiency Fo and maximal fluorescence Fm of B. innermis in the mixed sowing treatments were higher than those in the monocropping treatment, and the photosystem Ⅱ potential active center Fv/Fo value of the monocropping treatment was higher than that in the mixed sowing treatments. Under different mixed seeding methods, the capture of light energy per unit area (TRo/CSo) values of the two kinds of forage grass were smaller, and a spacing of 30 or 45 cm between alternating rows yielded higher chlorophyll fluorescence parameters. Therefore, mixed seeding with a spacing of 30 cm or more between alternating rows can yield a high photosynthetic efficiency and high interspecific competition between legume forages, resulting in high component stability and performance for this mixed seeding pattern.