Changes of Weed Communities by Methods of Cultivation in Winter Cropping on Drained Paddy Fields : (1) Influence of plowing time on the structure of weed communities and the quantity of weeds

[摘要] 1) The structure of weed community was changed with plowing time. The quantity of weeds decreased strikingly as the plowing time was delayed (Fig. 1). The relative intensity of influence of two factors (viable seeds population and emergence percentage) on the population of emergence was varied (Fig. 2). As the plowing is delayed, decrease in emergence percentage becomes more influencial in decreasing weed population, because the emergence percentage is closely related with air temperature (Fig. 3). 2) As the growth and yield of wheat are found to be scarcely effected by the delay of seeding time, it can be an effective method of weed control in wheat and barley cultivation in warm regions to regulate the seeding time according to the weed-density.

[学科分类] 农业科学（综合）