Day‐length and Head Formation in the Ryegrasses*

The importance of the time and extent of head production in the herbage grasses has been realized for a long time. In bay or silage making, or in grsiss drying, it deter‐mines tbe stage of maturity of the crop, and hence date of cutting, while in both hay and pasture tbe nutritive value of the herbage depends largely on the proportion of leaf and stem present. In seed production, the time of heading is of basic importance. It deter‐mines date of harvesting and so may affect yield of seed.