Ecological Studies on Alopeculus aequalis Sobol. : 1. On the influence of soil moisture and of the depth of soil layers over the seeds upon germination and emergence of them. : 2. On the temperature for germination and emergence, and seasonal variation in emerging capacity.

Abstract

As a fundamental study of controlling measures of Alopeculus aequalis, an annoying weed in wheat and barley cultivation on drained paddy fields, certain factors which would have closer relations to its germination and emergece, were examined. The results are as follows : 1. The optimum soil moisture for emergence of Alopeculus was found to be about 80 % of the water capacity (Fig. 1), being higher than that for wheat. The optimum, minimum and maximum air temperatures for emergence were about 15°, 5° and 23°C, respectively(Figs. 4 and 5). The depth of soil through which the weed can emerge differed according to soil moisture. Generally speaking, the limit of it was about 4cm. which is very shallow as compared with that for wheat. It may be natural that frequency of emergence should be closely related with the density of distribution of viable seeds within the top layer of soil. The population of viable seeds decreased from day to day after the field was drained in autumn (Fig. 6). 2. Emergence of this weed in paddy fields occur most vividly in autumn after they have been drained, and also in spring. Its population may be decreased by means of late autumn tillage 3. In wheat and barley cultivation on drained paddy fields, later seeding should be a very effective measure of controlling that weed.