COMPARISON OF TISSUES FROM SOLID- AND HOLLOW-STEMMED SPRING WHEATS DURING GROWTH: I. DRY MATTER AND NITROGEN CONTENTS OF PITH AND WALL AND THEIR RELATION TO SAWFLY RESISTANCE

Abstract

The dry matter content of the internodes of the wheat varieties, Thatcher, Rescue, and Golden Ball, grown on non-irrigated land varied with age, variety, and internode. The nitrogen content of the stem tissues varied from 6 per cent for immature to less than 1 per cent for mature tissues. The nodes of these wheat plants generally contained less dry matter and more nitrogen than did the internodes. At maturity the top third of each of the two uppermost internodes of Thatcher grown on irrigated land contained the highest percentages of dry matter and nitrogen, and the bottom third contained the lowest. The stems of the wheats and of Eagle oats were not greatly different in dry matter and nitrogen content during the period when larvae of the wheat stem sawfly, Cephus cinctus Nort., usually die in oat plants.Resistance of solid-stemmed wheats to the sawfly does not appear to be associated with a quantitative nutritional deficiency of either moisture or nitrogen. The analyses are consistent with the hypothesis that older larvae in solid-stemmed wheats die as a result of desiccation. Pith of Golden Ball contained more moisture than did that of Rescue, which supports the view that greater egg mortality may occur in the former variety because of the higher moisture content.