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

Effects of Planting Date on the Growth and Yield of Two Potato Cultivars Grown from Microtubers and Conventional Seed Tubers(Agronomy)

This study clarified the effect of planting date on the growth and yield of potato (Solanum tuberosum L.) plants grown from conventional seed tubers (CT) and microtubers (MT). CT of about 50 g and MT of 1 to 3 g of early (Kitaakari) and late (Norin 1) maturity cultivars were planted at Hokkaido University, Sapporo, Japan, on May 13, June 4 and June 25, and their growth and yields were investigated. The linear increase in leaf area index started later, but thereafter was higher in MT plants than in CT plants, irrespective of cultivar and planting date. Tuber formation was later in MT plants than in CT plants of both cultivars, but this difference was smaller on the last planting date. The linear increase in tuber dry weight started later in MT plants than in CT plants, but the rate of increase was similar in MT and CT plants of both cultivars and on all planting dates. Delaying the date of planting reduced the tuber yield, mainly because of the shortening growing period in MT and CT plants. The reduction in tuber yield and growing period was greater for the late cultivar Norin 1 compared with the early cultivar Kitaakari of CT and MT plants. Despite the climatic variations among the planting dates, MT plants yielded 71 to 90% of tuber fresh weight relative to CT plants, suggesting that MT are a good alternative as propagules for potato cultivation in countries where seed production is difficult

Genetic improvements for high yield and low soil nitrogen tolerance in rice (Oryza Sativa L.) under a cold environment

Eight rice cultivars released in 1905, 1919, 1941, 1954, 1971, 1984, 1987 and 1988 were investigated to identify the traits that contributed to high yield and low soil nitrogen tolerance breeding under cold environment. They were grown in fields at three different nitrogen (N) fertilizer treatments, 0, 6 and 12 g N m(-2) (0 N, 6 N and 12 N) in Sapporo, Northern Japan, in 2001 and 2002. All cultivars; increased their grain yield (GY) with the increase in soil N availability, and better response to N was observed in modern cultivars; released during 1984-1988 compared to old ones (1905-1954). Irrespective of N treatments, the modern cultivars showed better GY than the older ones. Absolute genetic gain was 2.15 or 2.94 g m(-2) year(-1) at 6 N and 12 N. Under 0 N treatment, although the magnitude of yield increase was small, the genetic gain in GY was still observed at 0.78 g m(-2) year(-1). The GY increments were achieved mainly through increasing the number of spikelets (SPK) which depends on the number of panicle (PAN) at any level, and the PAN could be increased by enhancing the number of tillers. The extinction coefficient (k) showed that the older cultivars had a spreading plant type, on the other hand, the modern cultivars had an erect plant type which seemed to be a better plant structure in terms of light distribution. This change on plant structure would allow the modern cultivars to have a larger LAI with improved light capturing resulting in better GY in modern cultivars; than the old cultivars having similar LAI with modern cultivars. These breeding strategies could work for the high-yielding rice breeding program under cold environments irrespective of soil nitrogen conditions