Ecological Studies on Alopeculus aequalis Sobol : 5. On the influence of light intensity upon growth of the weed, viability of seeds at various stages of maturity and seed production. : 6. On the compost and the methods of field management as agents in seed dissemination.

Abstract

As a fundamental investigation of controlling Alopeculus aequalis, one of the dominant weeds in winter cropping on drained paddy fields, seed production and seed dissemination were studied. The results are as follows : 1. Continuous shading started half a month before or soon after heading time of the weed affected on the growth of the weed, viability of seeds at various stages of maturity and seed production (fig. 1-3). 50% shading of sunlight was less influential, except causing only slight decrease in the seed viability when shading was started half a month before heading. By 80% shading of sunlight which was much more influential on growth and seed production, number of viable seeds was decreased distinctly at various stages of maturity. It was caused by decreased number and low-ered viability of seeds as a result of decreased ear numbers and retarded ripenning respectively. 2. It was found that seeds of the weed lose easily their viability by storage in compost-high temperature treatment (fig. 4). Because the seeds were rapidly destroyed during fermentation process of the compost, the compost can not be the carrier for seed dissemination. It was also found that seed dissemination in fields takes place mainly with seeds shattered from weeds growing in field, and generally speaking, the following seeds are not so important (fig. 6): seeds produced last year which remain alive in soil, seeds shattered on field from weeds growing on footpath, and seeds carried by water from irrigation channel or neighbouring field.