Associations Between Stem Solidity, Soluble Carbohydrate Accumulation and Other Characters in Wheat

Studies on the stem characteristics and yields of pith-filled (‘solid’) and hollow-stemmed selections from ten crosses between winter wheat genotypes were carried out in experiments in the field in 1976 and 1977. Samples of stems were taken 10–14 days after anthesis when stem weights and the concentration of ethanol-soluble carbohydrates (sugars) they contained were maximum. Although the d. wt per unit length of stem was greater in the solid than in the hollow selections there was no difference between them in maximum stem weight or sugar concentration. Thus there was no difference between them in the maximum amount of sugar they contained. In a separate study, it was found that the pith in the solid-stemmed selections, which consisted of undifferentiated parenchymatous cells, comprised 11 per cent of the total stem d. wt and contained 13 per cent of the sugar in the entire stem. Solid-stemmed selections were shorter at maturity and had narrower stems than their hollow counterparts. Grain yields from the two types were similar in 1976 and 1977. The genetic and environmental determination of stem solidity and the reasons why the character had no effect on yield are discussed. It is suggested that the greater apparent stiffness of solid stems may confer increased resistance to lodging.