Abstract
These experiments were made to clear seasonal growth pattern and growth analysis of Ladino clover (Trifolium repens L., race giganteum). 1. Maximum root emergence and axillary bud initiation were observed at a time when herbage growth was generally slow or ceased, viz. from autumn to winter, while maximum herbage growth occurred when root initiation was very slow and decay of old roots took place. It suggests that depression of root may have been due to development of flower primordia, exhaustion by herbage growth and ill effect of high temperature. 2. It was confirmed that the wight of underground organs decreased from April (sprouting period) to August and increased from October to January in a Ladino clover sward. This reduction of underground organs in spring was associated with flowering and maximum herbage growth, especially it being rapid during rainy season. 3. On the relationship between the growth of roots and that of stolons in maximum growing season of underground organs, first stolons became enlarged as a result of high accumulation of reserve foods, part of the foods being consumed for initation and development of roots. Peak of root growth successively occurred after that of stolons in February. 4. Total dry matter production of autumn was almost equal to that of spring, but herbage yields were greatly lower in autumn that in spring. A great deal of assimilation products was translocated to stolon part in autumn, while stored substance in underground organs as well as assimilation products were consumed for herbage growth in spring. 5. Dry matter production was analysed by net assimilation rate (NAR for short) and leaf area index (LAI, F being mean LAI). The relationship between NAR and F was found to be NAR=a-bF, while optimum LAI=a/2b, b value depending vertical distribution of leaf layer and leaf shape. The maximium LAI reached to 5.7 in spring and near maximium LAI was again attained about 4 weeks after cutting. The regression line of NAR calculated was 41.4-7.2F for growing season and optimum LAI obtained was 2.9 in a Ladino clover sward. In order to obtain high yields, it is suggested that Ladino clover stands have to maintain plant height taller than 30cm for regrowth periods.
