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Performance of Pure and Mixed Stands of Forage Grasses at the Establishment Phase. I. Two and Three Species Mixtures
F. F. Bebawi and Robert E. L. Naylor
The New Phytologist
Vol. 89, No. 2 (Oct., 1981), pp. 347-356
Stable URL: http://www.jstor.org/stable/2432071
Page Count: 10
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In two species mixtures over all nutrient levels and harvests, mixtures of cocksfoot and timothy invariably gave relative yield total (RYT) values well above 1.0 thus implying a synergistic relationship, while mixtures of cocksfoot and perennial rye grass (PRG) consistently gave RYT values well below 1.0 thus indicating a mutually antagonistic relationship. However, mixtures of PRG and timothy generally gave RYT values approaching 1.0. Similarly mixtures of cocksfoot and timothy overyielded their respective highest yielding pure stands and mixtures of cocksfoot and PRG underyielded their respective lowest yielding pure stands. PRG and timothy generally gave intermediate yields between those of their highest and lowest pure stands. Relative yield values over all nutrient levels and harvests revealed that PRG is more aggressive than cocksfoot, which in turn is more aggressive than timothy. In a three species mixture this trend in order of aggressiveness was also maintained. The yields of the three species mixtures invariably exceeded those of their highest yielding pure stand. In both experiments pure stands of cocksfoot gave the highest yields and timothy the lowest. Nitrogen fertilization significantly affected herbage yield maximizing it at high nutrient level. There were also significant differences in yield between harvests over all nutrient levels. However, the particular combination of species in a mixture affected the mixture behaviour and yield, though generally the behaviour of a component in a mixture was not predictable from a knowledge of its behaviour in pure stands. The present findings also suggest that the hypothesis that mixtures yield more than pure stands is untenable as a general statement about all mixtures.
The New Phytologist © 1981 New Phytologist Trust