Mechanism of the rice hull‐induced germination of Monochoria vaginalis seeds in darkness

Abstract

The seeds of Monochoria vaginalis require light to germinate. However, they are able to germinate in darkness in the presence of rice hulls. The mechanism of this phenomenon was investigated in this study, in which only the unsterilized seeds of Monochoria were induced to germinate by the presence of a rice hull extract. The rice hull extract was able to be replaced by either a mixture of amino acids and phosphate or a yeast extract. The culture media in which germination was observed always showed turbidity, indicating the propagation of bacteria, which were identified as Bacillus sp., Pedobacter sp., Pantoea sp. and Sphingomonas sp. Treatment with the individual bacterial species or combinations of these bacteria induced Monochoria seed germination when added to the media containing the rice hull extract. It was concluded that the rice hull extract accelerates the propagation of bacteria, which in turn digest the seed coat of Monochoria, facilitating its germination.

Factors Promote Germination and Initial Growth of <i>Monochoria vaginalis</i>

“…The extracts of rice hulls have been reported to stimulate germination of Monochoria in both light [14,15] and darkness but with unsterilized rice hulls [10]. However, findings of this study, in contrast, showed that aqueous extracts of rice hulls did not provide induction of Monochoria germination.…”

“…However, findings of this study, in contrast, showed that aqueous extracts of rice hulls did not provide induction of Monochoria germination. In this study, the concentration was 1000 ppm using only distilled water, but in the previous researches, the extracts from rice hulls were the combination of both distilled water and methanol [10] and ethyl acetate [15], which may contribute to the different results obtained from this study. However, Yokota et al [10] reported that in darkness, sterilized rice hulls gave no induction of Monochoria germination, and explained that bacteria such as Bacilus sp., Pedobacter sp., and Sphingomonas sp.…”

“…An amount of 100 rice seeds was immersed in 100 ml distilled water in a glass beaker for 2,4,6,8,10,12,14,16,20, and 22 days in the growth chamber. The exudates were filtered by filter papers and an aliquot of 10 ml of the extracts was put into a 9 cm diameter Petri dish with 10 seeds of Monochoria.…”

“…Yokota et al [10] reported that rice hull extracts accelerate the propagation of bacteria such as Bacillus sp., Pedobacter sp., Pantoea sp. and Sphingomonas sp., and they digested seed coats of M. vaginalis, therefore facilitated the weed germination.…”

“…and Sphingomonas sp., and they digested seed coats of M. vaginalis, therefore facilitated the weed germination. The role of possible germination stimulators from rice seeds in darkness was eliminated [10]. To understand the factors involved in germination of Monochoria seeds other than rice, such as barnyardgrass, is also a major problematic weeds in paddy fields is indispensable.…”