Metabolic Changes Associated with Vernalization of Wheat I. Carbohydrate and Nitrogen Patternsl

Sumintary. A spring wheat (Triticumo aestivumin) and(I anl obligate winter wheat (Triticumt compactutm) variety were each grown for 5 weeks in controlled environments at 20 and 250. The threshold for flower induction in the winter wheat was 4 to 5 weeks at 20, whereas the spring wheat had no low temperature requirement for flowering. Changes in the levels of carbohydrate and nitrogen fractions in the wheat leaves were determined during their growth in the cold and warm environments. There was an enhanced accumulation of the 5 carbohydrate fractions in both wheat varieties grown at 20 compared to 250. Highly significant differences in the levels of sucrose, oligosaccharides, and starch were found between the spring and winter varieties grown at 20. The winter wheat seedlings grown at 20 accumulated much more of these carbohydrates than the corresponding spring wheat. The carbohydrate patterns in both varieties grovin at 250 were nearly identical except for the final 2 weeks of groxvth. The level of nitrogenous substances in the tissues grown at 20 was mluch higher thani in the corresponding tissues grown at 250. The onily significanit differenice between the spring and winter varieties was in the soluble proteirn fraction. This fractioni rose nlearly 3-fold in the winter variety grown at 20° whereas it remiiain.e(d inearly constant in the similarly grown spring wheat. MIost of the changinig clhemiiical p)atterns ol)serve(l in relation to the vernalization treatment appear to be miietabolic alterationis associate(d vitlh low temperature rather than alterationis directly related with the vernalization response.