The influence of the time of starting irrigation on the tillering and yield of rice plant in direct sowing culture.

[摘要] 1. Effect of irrigation at different times of growing season on the tillering and yield of rice plants in direct sowing culture was studied in the glass house. 2. In the plots receiving no irrigation during early stage of growth, the tillering period was delayed as compared to the other plots. 3. In the plots, which received irrigation from the 12th leaf stage on, plants continued to tillering until the latest time. 4. Plot having no irrigation during early stage of growth showed low percentage of available tillers (tillers bearing ears) but the plot received irrigation from 9th leaf stage on gave high percentage of available tillers. 5. Irrigation from the 3rd leaf stage on causes secondary and tertially tillerings formation. 6. Irrigation from the 6th leaf stage causes the largest number of stems than all thier plots. 7. Irrigation from the 9th leaf state and from 12th leaf stage result in the greater yield than all other plots. In the usual method of rice culture which contains transplanting the practice named "Nakaboshi" (dry up the paddy field at a certain time) is said to be useful to obtain the greater yield. However in the case of direct sowing culture, it was found that the irrigation starts at that time gives the best effect on yield.

[学科分类] 农业科学（综合）