Intra-varietal variation. In lolium perenne

The intra-varietal variation of plants of Irish and S. 23 perennial ryegrass (Lolium perenne) growing in nutrient solution was studied in separate experiments.The variation in shoot growth was due to differences in both the rate of production and size of the tillers, while in root growth it was related to the size of individual roots. Root relative to shoot growth was also related to the size of the individual roots.In both varieties the frequency-distribution of size of individual roots and rate of root growth compared with shoot growth was positively skew. Root characters were more variable than shoot characters. The results are discussed in relation to possible selection pressures and morphology.