A possibility of influence factors on winter physical damage of grapevines in a snowy vineyard

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 itself and its interaction with vineyard slope and grapevine 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 'Gewürztraminer', even in the flat zones. The magnitude of the distortion coincides with the mortality of grapevines. Although the changes 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 damages of grapevines in vineyards in heavy snowy regions

Yield losses of soybean and maize by competition with interseeded cover crops and weeds in organic-based cropping systems

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 establishment of main crops. Consequently, soybean yield was the highest in Post-MC and decreased by 29%, 18% and 7% in Sole-MC, Pre-MC and Syn-MC, respectively, and maize yield was also the highest in Post-MC and decreased by 68%, 100% and 24% in Sole-MC, Pre-MC and Syn-MC, respectively. It was concluded that weeds could be controlled effectively by sowing cover crops after planting main crops in organic farming systems in a snowy-cold region

A possibility of influence factors on winter physical damage of grapevines in a snowy vineyard

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

Comparison of Growth and Grain Yield of Spring Wheat in Lhasa, the Tibetan Plateau, with those in Sapporo, Japan

The Tibetan Plateau is one of the highest cultivated regions in the world. The objective of the present study was to compare wheat growth and grain Odd in We high altitude region with those in a low altitude region. Two spring wheat. cultivars wow grown for two years at an experimental field in Lhasa (29 degrees N, 3688 m above sea level in the Tibetan Plateau in 2001 and 2003 and in Sapporo (43 degrees N, 15 m above sea level), Japan in 2002 and 2003. In Lhasa, temperature throughout the growth period was lower and photoperiod before heading was shorter than in Sapporo. There was no significant difference in grain yield between Lhasa and Sapporo. Dry Matter production) was higher in Lhasa than in Sapporo. The crop growth line before heading was similar in both locations, but Me time to heading was 15 days longer in Lhasa than in Sapporo. I oaf senescence inn more decelerated ill Lhasa than in Sapporo. These results suggested that high dry matter production in Lhasa was mainly Clue to the longer growth period