Abstract
Specific differences in the content of Na, Ca, Mg, Fe, Mn and Zn and in their variations with the progress of the growth were studied among Rhodesgrass (Chloris gayana). Dallisgrass (Raspalum dilatatum), Bahiagrass (Paspalum notatum), blue panicgrass (Panicum antidotale) and orchardgrass (Dactylis glomerate) grown under the same field conditions. 1. Na concentration of Rhodesgrass varied within 0.28-0.44%, showing the highest concentration in the end of August, while Na concentrations of other grasses varied within 0.02-0.03%, showing no consistent tendency in the variation with the progress of the growth and in the speific differences in Na content among them. The largest Na content of Rhodesgrass (3.7g/m^2) was 10 times or more higher than in other grasses, indicating the strong Na-absorbability of Rhodesgrass. 2. The specific defferences in the variation pattern of Ca concentration with the progress of the growth were not clear. No consistent specific difference in Ca concentration was found throughout the experimental period. 3. The variation pattern of Mg concentration with the progress of the growth in each grass was appeared to be considerably different. Mg concentration of Rhodesgrass was constantly about 0.09% throughout the experimental period and lower than in other grasses at all the sampling time. The largest Mg content of each grass was in the following order ; Bahiagrass (1.96g/m^2)>Dallisgrass (1.65g/m^2)>orchardgrass (1.17g/m^2)>blue panicgrass (0.90g/m^2)>Rhodesgrass (0.81g/m^2). 4. Fe concentration of each grass generally increased in the vegetative stage. The specific differences in Fe concentration were not large, though that of Dallisgrass was relatively low. 5. The variation patterns of Mn concentration with the progress of the growth were different among the species. Mn concentration of blue panicgrass varied within 100-140ppm throughout the experimental period and was considerably low as compared with those in other grasses. In the vegetative stages, Mn concentration of orchardgrass was evidently higher than in the warm-season grasses. The largest Mn content of each grass was in the following order ; Rhodesgrass (390mg/m^2), Dallisgrass (372mg/m^2)>Bahiagrass (289mg/m^2), orchardgrass (157mg/m^2)>>blue panicgrass (43mg/m^2). 6. Zn concentrations of four warm-season grasses were less than 50ppm until the end of September and increased rapidly in the end of the growth period. On the other hand, Zn concentration of orchardgrass was relatively high in the vegetative stage. Zn concentration of orchardgrass was generally higher than in the warm-season grasses, among which were not found a definite specific difference in Zn concentration. 7. There were evident differences in the cation composition between Rhodesgrass and other grasses at around heading stages. The cation compositions were K(45-51%)>Na(21-28%)>Ca(17-20%)>Mg(10-11%) in Rhodesgrass and K(57-71%)>Mg(15-26%)>Ca(10-16%)>Na(1%) in other grasses, among which there were not found marked differences in the cation compositions. Dallisgrass contained relatively higher concentration of K, resulting in the highest value of K/(Ca+Mg): 2.3-2.5 in equivalent ratio. The cation compositions mentioned above were discussed in relation to mineral nutrition of livestocks.
