The evaluation of selections of white clover (Trifolium repens L.) inmonoculture and in mixture with grass

Summary

• 1. Forty-nine clones and 25 families of white clover were tested in monoculture and in association with grass. The monoculture was mown only. The mixed cultivation was subdivided in a grazed part and a mown part.

• 2. Comparison of the families at the end of the second year after sowing showed rather low correlations for the characteristics area and density in monoculture and area in mixture. For height and type in monoculture and area in a mixture with grass correlations were even lower. The finer-leaved types of monoculture often performed better under mixture/grazing, but did not belong to the best. Under this kind of utilization the coarse Ladino types were frequently worse. They indeed often ranked among the worst. There was a very close relation between density and area in pasture. The correlation of area in mixture/mowing for the families of clover with area in monoculture was lower than the correlation between the same characteristic in mixture/grazing and monoculture. For the clones the correlation coefficients were lower than for the families. Among the characteristics themselves differences in correlations were found similar to those of the families.

• 3. For the best families in monoculture the correlation with growth in mixture is often higher than for the average of the other families.

• 4. In the second year after sowing the correlation between spread of clover in mixture/mowing and in mixture/grazing was very low.

• 5. Mass per area and density under monoculture in the year of sowing appeared to be moderately correlated with area under mixture/grazing in the second year after sowing as far as the families are concerned. For the best objects the correlation was higher. In a similar comparison area appeared to have much less significance than density.

• 6. Under grazing conditions the mother clones of the two best families showed the greatest number of surviving plants, indicating thus a clear inheritance of the competitive ability.

• 7. If breeding clover for cultivation with grass is intended, one must include clover/grass mixture in the selection scheme. Mixture/mowing and mixture/grazing require a rather great number of replications. Another disadvantage of testing under grazing is the need for cattle. On the other hand testing with a clover/grass association does not require so much weed control, which is a great advantage, ince weed control in a monoculture demands expensive labour.