Weed seed predation is an important ecosystem service in paddy areas. To conserve and sustainably utilize this service, it is necessary to quantify the seed predation and reveal the relative ...contributions of seed predators. In this study, we quantified the extent of postdispersal seed predation of Lolium multiflorum Lam., a non‐native invasive grass weed, on levees of terraced paddy fields located in a traditional cultural landscape (satoyama landscape) of Japan. We investigated the temporal variability in seed predation of L. multiflorum during summer after the seed shed, and estimated the total seed loss due to predation on the levees of terraced paddy fields for 2 years. Furthermore, the relative contribution of invertebrates and vertebrates to the seed predation was estimated based on exclosures. The total seed loss due to predation during 4 months (from late June to late October) was consistently high (>99%) in both years (the maximum proportion of seed predation per 2 weeks = 80.0–86.7%). The seed predators were likely to be mainly invertebrates such as crickets and ground beetles. This study revealed that the seed predation intensity was consistently high and can be an important depletion factor for the seedbanks of weeds such as L. multiflorum on the levees of terraced paddy fields. The high intensity of seed predation by invertebrates might suppress the invasion and population expansion of L. multiflorum on the levees of terraced paddy fields.
The regular pruning in the cultivation of kiwifruits (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson) is necessary to maintain fruit productivity and quality, and the pruning generates a ...significant amount of wastes. In this study, allelopathic activity of pruning branch wastes was investigated to discover beneficial applications of the wastes. An aqueous methanol extract of pruning branch wastes inhibited the growth of cress (Lepidum sativum L.), lettuce (Lactuca sativa L.) and alfalfa (Medicago sativa L.) and weed species, Lolium multiflorum Lam., Vulpia myuros (L.) C. C. Gmel., and Echinochloa crus-galli (L.) P.Beauv. Significant reductions in the growth were observed as the extract concentration was increased. The effectiveness of the extract varied by these plant species. The extract was then separated by several chromatographies with monitoring the inhibitory activity and the most active substance in the extract was isolated. The substance may work as an allelopathic agent because of its growth inhibitory activity. The present research suggests that kiwifruit pruning branches wastes may have allelopathic activity and be potentially useful for weed control in several agricultural field conditions. Further investigation is, however, necessary in the field conditions to develop the practical application of the pruning wastes.
Mowing weeds in rice paddy field ridges is essential for weed management. However, excessive mowing causes the dominance of the Poaceae weeds, which are host plants for rice stink bugs. In this ...study, the authors hypothesized that high mowing is more effective than low mowing in decreasing the dominance of Poaceae weeds. The dominance of the Poaceae weeds between high mowing (cut at a height of 5–10 cm) and low mowing (cut at ground level) was compared across 5 sites. As a result, the cover-abundance ratings of the Poaceae weeds were lower in the high mowing plots than that in the low mowing plots in all sites. In addition, the biodiversity index was higher in the high mowing plots than in the low mowing plots in each site. It was concluded that the increased mowing height effectively decreased the dominance of Poaceae weeds and this can be used as a strategy for controlling rice stink bugs.
▶ The extent of seed predation of Italian ryegrass in converted paddy fields was quantified. ▶ The total seed loss due to predation in the interior areas of fields was 35–43%. ▶ The total seed loss ...due to predation in the boundary strips was 42%. ▶ The seed predation is an important depletion factor of post-dispersal seeds of Italian ryegrass.
The extent of post-dispersal weed seed predation in upland wheat fields converted from paddy fields was quantified in Shizuoka Prefecture, central Japan. We investigated the temporal variability in seed predation of Italian ryegrass (Lolium multiflorum Lam.), a non-native winter annual weed in Japan, during summer after the seed shed in both the field interior areas and boundary strips, and estimated the total seed loss due to predation during the summer. Furthermore, the contribution of invertebrates and vertebrates to seed predation was estimated by using exclosures. The total seed loss due to predation during four months (from late June to late October) in the field interior areas and boundary strips was estimated to be 35–43% (the maximum proportion of seed predation per two weeks=27%) and 42% (25%), respectively. The seed predators in the field interior areas were vertebrates (rodents or birds) and invertebrates (crickets and ground beetles). In contrast, seed predators in the boundary strips were mainly invertebrates (crickets and ground beetles). The results of this study suggest that predators make a substantial contribution in the depletion of post-dispersal seeds of Italian ryegrass in converted paddy fields.
We investigated the ecological management of the rice stink bug, Stenotus rubrovittatus, which immigrates into rice paddies in early spring after its abundance increases on Poaceae weeds. The bugs ...occurred on a few host weed species and these weeds grew in a limited number of sites in paddy fields. Therefore, managing these weed species in spring would be an effective means of controlling S. rubrovittatus. In spring, the population of wolf spiders (Lycosidae) in paddy fields where Chinese milk vetch, Astragalus sp., was cultivated was larger than in fields without vetch, and the number of wolf spiders in fields containing Chinese milk vetch was consistently higher during the rice-growing period. We also observed that crickets (Gryllidae) feed on the seeds of Poaceae, which are the host plants of S. rubrovittatus. These results suggest that crickets may indirectly help to control the S. rubrovittatus population. Crickets were more abundant on paddy ridges where cover plants were cultivated than on ridges without cover plants. Based on these results, we suggest that ecological management that enhances the ecosystem services of rice paddies would be effective for regulating S. rubrovittatus populations.
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