Dry Matter Production in Ladino Clover Sward

[摘要] The dry matter production of a ladino clover sward was investigated and some analysis of its growth were made during both periods of late spring to summer and of atumn to early winter. The work was carried out at Tohoku University farm (volcanic ash soil) located in northern Japan. Pure stands of ladino clover, two years after sowing were clipped up to 7 cm above the ground level on the 14th of June and 4th of October. Starting on these dates, plants were harvested with intervals of 5 to 10 days with randomly sited quadrat of 20×20 cm over a period of 6 to 7 weeks. The plants in each quadrat were separted into the root, stolon, leaf petiole and leaf lamina. Dry weight of each part and area were measured. The dry weight of leaves was higher in June than in October, wheras that of stolon and root was higher in October than in June. Dry weight of total plant was nearly the same in June and in October (fig. 1). Stolon and root dry weight decreased more sharply and for longer duration in June than in October. It was thought that the sharp decrease of weight of these storage organs in June was associated with the fast development of LAI or leaf weight (fig. 2). The growth process after defoliation was separated into two stages, namely (1) the stage in which root and stolon weights decrease and the fast development of new leaves occurs, and (2) the stage in which root and stolon weights increse and slow developmant of leaves occurs. The amount of net prduction was 8.4 g, m-2, day-1 in June and 4.9 g, m-2, day-1 in October. From these values, length of growing period and actual production of fresh weight, it was estimated that net production of the ladino clover sward in moderate productivity was about 1.2 kg, m-2, year-1 and was about 1.8 kg, m-2, year-1 in high productivity in Japan. LAI reached a maximum value of 3.15 in June and 3.36 in October. It was noticed that LAI increased faster and reached the maximum value in a shorter period in June than in October (table 1). The value of leaf area duration was nearly the same in June and in October, whereas the value of NAR was higher in June than in October for most (o the Period of regrowth. It was thought that the low value of NAR was one of the cause of low production in October and that some effect of frost on. Leaves had relation to the decrease of NAR (table 2). A comparison of net production per day, NAR and LAI suggested that this clover was inferior to sweet potato and rice plant in dry matter production.

[学科分类] 农业科学（综合）