| Abstract/Contents: | "The present investigation was undertaken to elucidate the intergeneric and interspecific differences of early growth following emergence in various temperate grass species as shown in Table 1, which were grown under field conditions during September to November. Ten characters as criteria for early growth, such as number of tillers, number of leaves of main tiller, plant height, leaf width, leaf area, leaf weight, stem weight, plant top weight, specific leaf area (SLA), and leaf weight ratio, were measured at 45th day after emergence. The results obtained were as follows; 1. All the characters, except for number of leaves, SLA and leaf weight ratio, showed wide range of variation in temperate grasses. Leaf area, stem weight, leaf weight and plant top weight were highly and positively correlated with each other, while number of tillers, number of leaves, SLA, and leaf weight ratio were scarcely correlated with the other characters. 2. Principal component analysis based on number of tillers, number of leaves, plant height, leaf width, leaf area and plant top weight was applied to 126 varieties and strains, excluding 5 varieties of Avena sativa and Secale cereale which showed apparently higher productivity in early growth than the other species. The complex characteristics on early growth could be shown by the first two principal components which made cumulative contributions of 80% to total variations. The first principal component was mainly concerned with the productivity in earlly growth and the second principal component was mainly concerend with a plant type shown by number of leaves, number of tillers and plant height. The scatter diagrams presented in Fig. 6 demonstrated that there were clearly the intergeneric and interspecific differences of the early growth in temperate grasses. By the scores of the first principal component, the temperate grass species tested were loosely separated into 4 groups on the productivity as complex characteristics, which were designated as very high, high, low and very low groups, respectively. Each group included the following species; Very high group: Bromus rigidus, Avena fatua, Avena vaviloviana, Hordeum glaucum High group : Lolium multiflorum, Bromus catharticus, B. oxyodon, B. macrostachys, B. rubens, Haynaldia vilosa Low group: Lolium perenne, Arrhenatherum elatius, Phalaris minor, Alopecurus japonicus, 10 species of the genus Bromus Very low group : Dactylis glomerata, Phleum pratense, 3 species of the genus Festuca, 2 species of the genus Agropyron, Holcus lanatus, Phalaris arundinacea, Poa pratensis, Vulpia myuros By the scores of the second principal component, the intergeneric difference was clearly found between the genus Dactylis and the genus Festuca, or between the genus Lolium and the genus Bromus excluding B. catharticus. 3. There was poorly positive correlation between seed weight and the score of the first principal component (r=0.453**), indicating that the productivity in early growth was not always dependent on seed weight. The annual species tended to have higher productivity in early growth than the perennial ones, if about the same in seed weight. In the genus Bromus, however, B. catharticus as perennial species showed higher productivity than the other ones as annual excluding B. rigidus." |
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