Influence of total nonstructural carbohydrates on snow mold tolerance in winter wheat

now mold is an important disease of winter wheat in the Pacific Northwest, USA. It is most prevalent when snow covers unfrozen soil for long periods of time. Plants capable of accumulating large amounts of total nonstructural carbohydrates (TNC) before snow fall survive infection by psychrophilic fungi. Studies were conducted to ascertain the heritability of TNC in two hard red winter wheat populations. A preliminary study was arranged with genotypes of known tolerance to snow mold in the greenhouse. An experiment using randomized complete block design with four replications was planted in greenhouse and then transferred to a growth chamber at 4;To ascertain the narrow-sense heritability of TNC, field studies were conducted with lines derived from two hard red winter wheat populations. Three experiments were planted in 5x5 balanced square lattice designs with six replications at Tetonia, Idaho, during 1992-93 and 1993-94. Plant samples were collected prior to snow fall in all experiments and in one experiment, after snow melt, for TNC determination. Genotypes were highly significant (P = 0.01) for TNC, spring stand percentage and plant count in all of the experiments. Genotypic and phenotypic correlations among TNC, stand percentage and plant count were calculated. Narrow-sense heritability was determined for TNC, spring stand percentage and plant count. Irregular infection by Typhula idahoensis occurs in the field in most years in high snow fall areas. The method standardized for TNC extraction and quantification can effectively evaluate 100 plant samples per week. The fall TNC levels were less influenced by environment compared to spring TNC content. The narrow-sense heritability estimates for fall TNC were higher than spring survival. TNC may be used in selection of winter wheat genotypes derived from 'Manning'...