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Hokkaido in northern Japan is a typical subpolar region and wine production using traditional cultivars can be done recently. However, there is an issue that the grapevines have short life spans in snowy central Hokkaido. This study investigates the effect of snow it-self and its interaction with vineyard slope and grape-vine stiffness on physical stress. In comparison of the flatness of the vineyard, the distortion of the basal trunk in the slope zone was greater than in the flat zones in the snowy mid-season. In comparison between cultivars, the distortion of the basal trunk in the flexible 'Kerner' was greater than in rigid 'Gewurztraminer', even in the flat zones. The magnitude of the distortion coincides with the mortality of grapevines. Although the chang-es in distortion showed a transition in just two winter durations, these results suggested a possibility that the snow cover might be linked to one of the physical dam-ages of grapevines in vineyards in heavy snowy regions.

Hokkaido in northern Japan is a typical subpolar region and wine production using traditional cultivars can be done recently. However, there is an issue that the grapevines have short life spans in snowy central Hokkaido. This study investigates the effect of snow it-self and its interaction with vineyard slope and grape-vine stiffness on physical stress. In comparison of the flatness of the vineyard, the distortion of the basal trunk in the slope zone was greater than in the flat zones in the snowy mid-season. In comparison between cultivars, the distortion of the basal trunk in the flexible 'Kerner' was greater than in rigid 'Gewurztraminer', even in the flat zones. The magnitude of the distortion coincides with the mortality of grapevines. Although the chang-es in distortion showed a transition in just two winter durations, these results suggested a possibility that the snow cover might be linked to one of the physical dam-ages of grapevines in vineyards in heavy snowy regions.

Hokkaido in northern Japan is a typical subpolar region and wine production using traditional cultivars can be done recently. However, there is an issue that the grapevines have short life spans in snowy central Hokkaido. This study investigates the effect of snow it-self and its interaction with vineyard slope and grape-vine stiffness on physical stress. In comparison of the flatness of the vineyard, the distortion of the basal trunk in the slope zone was greater than in the flat zones in the snowy mid-season. In comparison between cultivars, the distortion of the basal trunk in the flexible 'Kerner' was greater than in rigid 'Gewurztraminer', even in the flat zones. The magnitude of the distortion coincides with the mortality of grapevines. Although the chang-es in distortion showed a transition in just two winter durations, these results suggested a possibility that the snow cover might be linked to one of the physical dam-ages of grapevines in vineyards in heavy snowy regions.

Hokkaido in northern Japan is a typical subpolar region and wine production using traditional cultivars can be done recently. However, there is an issue that the grapevines have short life spans in snowy central Hokkaido. This study investigates the effect of snow it-self and its interaction with vineyard slope and grape-vine stiffness on physical stress. In comparison of the flatness of the vineyard, the distortion of the basal trunk in the slope zone was greater than in the flat zones in the snowy mid-season. In comparison between cultivars, the distortion of the basal trunk in the flexible 'Kerner' was greater than in rigid 'Gewurztraminer', even in the flat zones. The magnitude of the distortion coincides with the mortality of grapevines. Although the chang-es in distortion showed a transition in just two winter durations, these results suggested a possibility that the snow cover might be linked to one of the physical dam-ages of grapevines in vineyards in heavy snowy regions.

Waterlogging conditions cause severe abiotic stress and reduce average yields in vegetable crops. Processing tomatoes are cultivated extensively worldwide, and are used in many food products. Recently, processing tomatoes have been cultivated in paddy fields in Hokkaido, northern Japan. Studies are needed to assess the responses of processing tomatoes to wet conditions. The goal of this study was to clarify the mechanisms of waterlogging injury, and to identify ways to mitigate wet injury in processing tomatoes. We used three cultivars in a two year pot experiment and a one year field experiment. Longer waterlogging treatments increased the severity of yield losses in both experiments. The waterlogging treatments initially caused reductions in fruit number and then in average fruit weight. The reductions in fruit number resulted from reduced fruiting ratios. The reductions in average fruit weight may have been triggered by multiple factors, including reductions in soil nutrients, reduced nutrient uptake due to hypoxia, and reductions in the photosynthetic rate. These results suggested that top-dressing with fertilizer after excess rain may help to mitigate yield losses. The waterlogging treatments also induced changes in fruit composition, with reduced water content and increased sugar/acid ratios. The responses to waterlogging treatment varied among cultivars, and we concluded that 'Natsunoshun' is a superior cultivar for cultivation in converted paddy fields that may become waterlogged after heavy rains.

Weed management is a major issue in organic farming systems. Although interseeding cover crops is one alternative to herbicides, cover crops often suppress not only weeds but also main crops. Therefore, using cover crops for weed control without adverse effects on main crop growth is important. To verify the effect of cover crops on competition between main crops, cover crops and weeds in a snowy-cold region, main crops soybean (Glycine max Merr.) in 2005 and maize (Zea mays L.) in 2006 were grown with cover crops winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), respectively. The cover crops were sown on three sowing dates: before main crop planting (Pre-MC), on the same date of main crop planting (Syn-MC) and after main crop planting (Post-MC). A plot without cover crops (Sole-MC) was used as a control. The dry weight (DW), vegetation cover ratio (VCR), vertical community structure and chlorophyll content were measured to estimate the competition between main crops, cover crops and weeds. Weed DW was suppressed significantly by sowing cover crops in both soybean and maize. This weed suppression was associated with the increase of VCR of main crops plus cover crops at the early growth stage of main crops. Soil seed banks of dominant weed also became lower by sowing cover crops, implying the importance of proper weed management for suppressing weeds successively. In addition, the sowing dates of cover crops had large effects on main crops DW especially in maize, i.e., it was significantly lower in Pre-MC and Syn-MC than in Post-MC. Although the cover crop height was markedly shorter than the main crop height, the chlorophyll content of the main crops was significantly lower when cover crops were sown earlier. These results suggest that the growth inhibition of main crops by cover crops was partly caused by competition for nutrients between main crops and cover crops, and this growth inhibition was alleviated when cover crops were sown after the es

Weed management is a major issue in organic farming systems. Although interseeding cover crops is one alternative to herbicides, cover crops often suppress not only weeds but also main crops. Therefore, using cover crops for weed control without adverse effects on main crop growth is important. To verify the effect of cover crops on competition between main crops, cover crops and weeds in a snowy-cold region, main crops soybean (Glycine max Merr.) in 2005 and maize (Zea mays L.) in 2006 were grown with cover crops winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), respectively. The cover crops were sown on three sowing dates: before main crop planting (Pre-MC), on the same date of main crop planting (Syn-MC) and after main crop planting (Post-MC). A plot without cover crops (Sole-MC) was used as a control. The dry weight (DW), vegetation cover ratio (VCR), vertical community structure and chlorophyll content were measured to estimate the competition between main crops, cover crops and weeds. Weed DW was suppressed significantly by sowing cover crops in both soybean and maize. This weed suppression was associated with the increase of VCR of main crops plus cover crops at the early growth stage of main crops. Soil seed banks of dominant weed also became lower by sowing cover crops, implying the importance of proper weed management for suppressing weeds successively. In addition, the sowing dates of cover crops had large effects on main crops DW especially in maize, i.e., it was significantly lower in Pre-MC and Syn-MC than in Post-MC. Although the cover crop height was markedly shorter than the main crop height, the chlorophyll content of the main crops was significantly lower when cover crops were sown earlier. These results suggest that the growth inhibition of main crops by cover crops was partly caused by competition for nutrients between main crops and cover crops, and this growth inhibition was alleviated when cover crops were sown after the es

Weed management is a major issue in organic farming systems. Although interseeding cover crops is one alternative to herbicides, cover crops often suppress not only weeds but also main crops. Therefore, using cover crops for weed control without adverse effects on main crop growth is important. To verify the effect of cover crops on competition between main crops, cover crops and weeds in a snowy-cold region, main crops soybean (Glycine max Merr.) in 2005 and maize (Zea mays L.) in 2006 were grown with cover crops winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), respectively. The cover crops were sown on three sowing dates: before main crop planting (Pre-MC), on the same date of main crop planting (Syn-MC) and after main crop planting (Post-MC). A plot without cover crops (Sole-MC) was used as a control. The dry weight (DW), vegetation cover ratio (VCR), vertical community structure and chlorophyll content were measured to estimate the competition between main crops, cover crops and weeds. Weed DW was suppressed significantly by sowing cover crops in both soybean and maize. This weed suppression was associated with the increase of VCR of main crops plus cover crops at the early growth stage of main crops. Soil seed banks of dominant weed also became lower by sowing cover crops, implying the importance of proper weed management for suppressing weeds successively. In addition, the sowing dates of cover crops had large effects on main crops DW especially in maize, i.e., it was significantly lower in Pre-MC and Syn-MC than in Post-MC. Although the cover crop height was markedly shorter than the main crop height, the chlorophyll content of the main crops was significantly lower when cover crops were sown earlier. These results suggest that the growth inhibition of main crops by cover crops was partly caused by competition for nutrients between main crops and cover crops, and this growth inhibition was alleviated when cover crops were sown after the es