抄録
Lodging of wheat and barley plants is regarded to be directly due to wind and rain. Wind forces exerted on plants or plant canopies were determined by mobile wind tunnel and measurement method of wind velocities over fields in previous papers. This paper deals with the influence of rainfall on lodging. Experiments with artificial rain and observations of rain and lodging in fields were made during ripening stage of wheat and barley plants in 1963 and 1964. Rainfall was supposed to affect lodging by increasing fresh weight of plants through wetting their surface, and increasing inclined angle of culms with kinetic energy of rain drops. Results obtained by artificial rainfall treatment indicated that lodging was caused by rain especially in case of weak wind (about 3 m/sec) when plant surface was fully wetted, and higher rainfall intensity led to heavier lodging both in field and isolated tiller. It was concluded from the results of observations of rain and lodging of plants that the lowest precipitation which caused lodging was about 3 mm, and no relationship was established between rainfall intensity and lodging. This was due to the fact that lodging was so often because of repeated rain in 1963. Results obtained by these experiments and observations seemed to support the above supposition concerned with influence of rainfall on lodging. Another influence of rainfall on lodging might be supposed, that is, rainfall would increase soil moisture and decrease soil hardness, resulting lower culm-support of soil. This will be discussed in a later paper.
