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SHUNJI KUROKAWA NORIHIRO SHIMIZU SUNAO UOZUMI YOSHINORI YOSHIMURA 《Weed Biology and Management》2003,3(1):28-36
The source of the velvetleaf spreading its distribution rapidly and causing serious problems in forage fields all over Japan since the mid 1980s was thought to be a new accidental introduction of seeds from velvetleaf mingled in some imported grains from the USA and Australia. However, velvetleaf used to be cultivated as a fiber crop until the 1880s. We examined the intraspecies variations, such as morphological characteristics and growth habits, using accessions previously collected and obtained from imported grains. Using principal component analysis (PCA), the accessions were classified into crop type and weed type. The crop type capsule was mostly an ivory color, and the weed type was mostly an ebony color. The crop type showed characteristics of a fiber crop, such as an erect form, uniform flowering and a low seed dormancy rate. Conversely, the imported grains were classified into the weed type which showed a strong weedy nature, such as branched form, long flowering period, high reproductive ability and a high dormancy rate. These results suggest that the new introduction is different from the indigenous fiber crop, and may possibly be the source of the present invasive velvetleaf because of its strong weedy nature. However, further studies comparing the new introduction directly with the present velvetleaf are necessary. 相似文献
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SHUNJI KUROKAWA NORIHIRO SHIMIZU SUNAO UOZUMI YOSHINORI YOSHIMURA 《Weed Biology and Management》2003,3(3):179-183
Velvetleaf seeds have been found in imported grains in Japan. The plants from these seeds show a weedy growth habit, such as that seen in the noxious velvetleaf which has recently emerged in Japan and noted in our previous study. To elucidate the genetic background of the velvetleaf strains found in imported grains we evaluated the genetic variation of six strains and an additional 39 worldwide velvetleaf accessions using the intersimple sequence repeat (ISSR) polymorphism. Cluster analysis based on the ISSR polymorphism emitted two major clusters which corresponded well with classification by growth habit, that is, crop type and weed type. Five of the six strains from the imported grains formed a small cluster. All six strains united into one major cluster containing the weed type accessions, while all of the old Japanese accessions formed another major cluster containing the crop type accessions. The genetic difference between imported weedy velvetleaf and old Japanese accessions suggests that imported velvetleaves are the source of the recent outbreak of the noxious velvetleaf in Japan. 相似文献
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ABSTRACT: The validity of using the RNA : DNA ratio, glycogen content, and C : N ratio in the columellar muscle as indicators of the nutritional condition in the Japanese turban shell Turbo cornutus was examined. These biochemical indices were compared between fed and starved animals. The fed animals were fed brown algae to satiation for 108 days as a control, whereas the starved animals were not fed for the first 75 days and then fed for next 33 days. All three indices declined during the starvation period, and the values for the starved group were significantly lower than those for the fed group during days 20–75. At day 108, after the re-feeding period, the indices for the starved group were found to have increased. Among the indices, only the RNA : DNA ratio for the starved males responded rapidly to starved conditions and became significantly lower even at day 4, and only the RNA : DNA ratio for the starved males and females recovered to those levels of the fed animals at day 108. The results indicated that the RNA : DNA ratio is the most rapid indicator of nutritional stress among the three indices. However, it is recommended that glycogen content and C : N ratio be used in addition to the RNA : DNA ratio for monitoring the health of T. cornutus as the RNA : DNA ratio showed large variations. 相似文献
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