Oat Stem Vascular Size in Relation to Kernel Number and Weight. II. Field Environment 1

Abstract

A high percentage of the dry matter accumulated in oat (Arena sativa L.) grain is transported through the phloem from vegetative tissues. Because vascular capacity may limit transport and thus panicle yield, we wanted to establish whether vascular capacity and panicle yield were related. In this study, we compared one component of vascular capacity, cross-sectional area of conducting tissue, among several cultivars differing in panicle yield and kernel weight. The number and size of vascular bundles, phloem area, and number of sieve tube members were measured in cross sections of the peduncle of several cultivars grown at Madison, Wis. and W. Lafayette, Ind. Cultivar and environmental differences were examined, and measurements were related to number and size of kernels produced. Significant differences among cultivars were found for most Vascular measurements. These differences were consistent at both locations. Cultivars grown at Indiana had significantly more inner bundles and greater inner bundle area than those grown at Wisconsin. All other traits were not influenced by location. There were many significant correlations between spikelets, kernels, and yield/panicle and the various vascular measurements, but kernel weight was not significantly correlated with any of the vascular measurements. Stepwise linear regression was used to construct models relating yield/panicle to the vascular characteristics. It was concluded that the number and size of vascular bundles develop in concord with the number of spikelets initiated. There was little evidence that the area component of vascular capacity of the peduncle restricted grain filling.