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Water soluble carbohydrates and growth potential of winter wheat as influenced by weather conditions during winter

Bergjord, Anne Kari, Skjelvåg, Arne Oddvar
Acta agriculturæ Scandinavica 2011 v.61 no.6 pp. 523-534
autumn, carbohydrates, carbon, climatic factors, crop yield, cultivars, models, overwintering, regression analysis, snow, snowpack, soil temperature, spring, vigor, winter, winter wheat, Norway
Although winter survival of winter wheat most often is recorded qualitatively by rating dead or living plants, the surviving plants may differ extensively in vigour and degree of carbohydrate reserves left at the end of winter. This factor is yet not accounted for in existing models of winter wheat yield and crop performance. A quantitative measure of plant vigour at spring arrival, as influenced by the prevailing winter weather and the plants’ concentration of water soluble carbohydrates, would hence make a useful supplement to such models. Two cultivars of winter wheat were grown in boxes over 2 years at three sites in Norway with contrasting winter climates. Plants were sampled monthly for measurements of growth potential and analyses of reserve carbohydrates. Fructan constituted the main part of water soluble carbohydrates (WSC). The concentration of fructan fell throughout winter, but increased rapidly after snow thaw in spring when a positive carbon balance was restored. Daily global radiation at plant level and soil temperature (2 cm) were the only two climatic factors found to have significant effects on periodic changes in fructan concentration in a stepwise regression analysis. Still, number of days with snow cover had a causal effect through its impact on soil temperature and radiation at plant level. In neither of the 2 years was there any significant correlation between plant carbohydrate concentration and growth potential at the different sites. The results implied that plant vigour at the end of winter was strongly related to plant condition in late autumn and duration of snow cover in winter. Plants that had been covered with snow for a long time period showed significantly lower growth at the samplings in March and April than plants from the location with a shorter duration of snow cover.