Studies on the Seed Production of Alfalfa : II. Effect of rainfall on seed production. : III. Effect of nitrogen applied before and after the bud formation stage on flowering, pod- and seed-setting.

[摘要] II. Some experiments were made from 1952 to 1955 to know the effects of rainfall on the production in alfalfa plants. The results obtained were as follows : 1. In 1953 and 1954, the first cutting was given at various dates making the initial blooming dates varied, and the resultant change in the numbers of pods and seeds was investigated. The largest number of pods was obtained from the plants of initial blooming date at 26 June 1953, while the largest number of seeds was from those of initial blooming date at 25 July, 1954. The coefficients of correlation of number of the days raining at 10, a. m. during the flowering period to those of pods and seeds were -0.967 and -0.787, respectively. 2. Two alfalfa plants were used to observe the pollen germination percentage. The germination percentage of the pollen collected on a rainy day was 12.2 % for one plant and 31.6 % for the other, while of that collected on a fine day it was 49.6% and 74.5%, respectively. 3. The effect of tripping on pod-setting was studied, giving various dates of tripping, i. e., on the day of blooming, first, second, third, and fourth days after blooming. The highest pod-setting percentage was shown in the plants whose flowers were tripped on the first day after blooming, and thereafter, the percentage tended to get lower with the advance of days. III. This investigation was made by means of sand-culture in 1954. Treatments were as follows: 1) Application of nitrogen before and after bud formation stage, 2) Application of nitrogen before bud formation stage only, 3) Application of nitrogen after bud formation stage only, and 4) No supply of nitrogen either before or after. The results obtained were as folloews : 1. The plant height and fresh weight were greater when nitrogen was applied than when it was lacking. 2. Application of nitrogen after bud formation stage, i. e. Treatments 1) and 3), prolonged the full bloom period. 3. The numbers of flowers, pods and seeds were larger in the Treatments 1) and 2) than in 3) and 4). 4. The percentage of pod-setting and seeds per pod were greater in Treatment 2) and 4) than in 1) and 3).

[学科分类] 农业科学（综合）