Study of Regeneration of Ladino Clover : I Regeneration of Ladino Clover according to Fertilizer Application Amounts and Cutting Seasons.

[摘要] (1) Field tests were made as to the regeneration of Ladino clover after cutting in the warm areas. From the viewpoint of dry matter productive function of Ladino clover grown in plant community, two plots were set up: moderate fertilizerplot (0 kg Urea per are and 3.3 kg KCl per are) and heavy fertilizer plot (1.1 kg Urea per are and 8.2 kg KCl per are). Clover cutting was repeated at intervals of time when the plants reached 30 cm in height. Thus the effects of clover cutting seasons on the Ladino clover regeneration were tested. (2) Ladino clover regeneration was affected greatly by each cutting season (June, August and October), but in every cutting season the plant growth tended to be stopped or slowed down about 20 days after cutting. The dry matter production showed an acclerating increase in June, but showed a marked decrease in and after August, and with the lapse of days after cutting, the dry matter production increasing rate tended to be slowed down or stopped. (3) As to the effects of the fertilizer application amount, the trend was observed that the Ladino clover regeneration in the heavy fertilizer plot was more vigorous in October (when the plant growth was retarded) and it showed increases in the dry matter production in heavy fertilizer plot over that in moderate fertilizer plot in every cutting season, particularly less in the slowdown of Ladino clover regenerating action in heavy fertilizer plot than that in moderate fertilizer plot even in August (high temperature summer month). (4) As high as 1.0 % significant negative correlation was found between net assimilative rate and leaf are a index in each cutting season. The regression coefficients were greater in order of October, August and June. The population's growth rate formed an optimum curve indicating the rise in the rate with the increase in leaf area index and then the fall to some extent, but the maximum values were greater in order of June, August and October. The regression coefficient was smallest in June and largest in October. In the case of heavy fertilizer plot, the peak was reached somewhat later, indicating that the range to approximate the optimum conditions was wider in the case of heavy fertilizer plot than in the case of moderate fertilizer plot. (5) Highly significant negative correlations were found between (a) the relative light intensity on the soil surface of 5cm thick where Ladino clover grown in plant community and (b) the leaf area index. With the increase in leaf area index, relative light intensity showed a decrease functionally. The decreasing rate was higher in order of October, August and June. And it showed a trend that the decreasing rate for moderate fertilizer plot was higher than that for heavy fertilizer plot. Thus it was inferred that the construction of the plant community varied with clover cutting seasons and the fertilizer application amount. (6) Carbohydrate content in Ladino clover runners was greatest in October. It showed a decrease in carbohydrate-content according to the season in which plant growth was forced. Viewed from the effects of fertilizer application amount, the accumulated amount of carbohydrate was larger in heavy fertilizer plot than that in moderate fertilizer plot, because though it showed a marked decrease in carbohydrate-content immediately after clover cutting, it was regained with rapidity.

[学科分类] 农业科学（综合）