Abstract
It has been reported that broadleaf dock (Rumex ob-tusifolius L., abbreviated as Rx in the following), one of the most noxious weed in intensive pastures, produces a large amount of seeds and that seeds are stored in the seed bank of the soil for many years and germinate occasionally. Moreover, it has been reported that pastures of high frequency of Rx are the fertile soil, and on the contrary, these of low frequency of Rx are the poor soil. A survey on the buried seed population has been carried out on 4 pastures with high freqency of Rx and on 4 pastures with low frequency of that. The following results were obtained. 1) The highest and the lowest frequency (%) values of Rx in pastures were 30.3 and 0.9, respectively. The mean frequency (%) value of Rx was 14.2±11.1. 2) The buried seeds of thirteen weed species were found, such as Rx, Polygonum persicaria, Digitalia ad-scendens, D. violascens, Cyperus microiria, Stellaria neglecta, and Viola verecunda, etc. A large amount of seeds of Echinochloa crus-galli were found but they were not survived, therefore it was excluded from a statistical analysis and a discussion. 3) High correlation coefficients were found between the Rx frequency and a number of the buried seed of Rx, and also between the Rx frequency and that of the eutrophic weed species such as Polygonum persicaria, Digitaria ad-scendens, and Chenopodium album, etc. This suggests that pastures Rx occur abundantly preserve a large amount of the buried seeds of Rx as well as that of the eutrophic weeds.
