Variability of stolon characteristics and response to shading in two cultivars of white clover (Trifolium repensL.)

Abstract

Abstract ‘Grasslands Tahora’ and ‘Grasslands Kopu’ white clover cultivars were compared for several shoot characters. Selections were made for high and low proportions of nodes branching, long and short internodes, and large and small leaves, and position of the first branch on the stolon within each cultivar. These selections plus a random sample of genotypes from each cultivar were regrown in full sunlight and in 50% full sunlight. Tahora and Kopu differed in all characters measured except stolon elongation rate and proportion of nodes active (i.e., the total producing branches and flowers). Tahora had branches occurring earlier on a stolon, a higher node production rate, and proportion of nodes branching, but smaller leaves, shorter petioles, thinner stolons, shorter internodes, and lower proportion of nodes flowering than Kopu. The two cultivars differed in skewness of frequency distributions for first branching, node, leaf size, proportion of nodes branching and flowering. Shading greatly increased petiole length and decreased proportion of nodes branching. However, there were significant cultivar × light intensity interactions for stolon elongation rate, leaf size, petiole length, internode length, and proportion of nodes branching. Genotypes selected originally for large leaves had larger leaves in the subsequent shading experiment than genotypes selected originally for small leaves. Similarly, the long internode selection subsequently had longer internodes than the short internode selection. However, genotypes selected originally for a high proportion of nodes branching were not subsequently different from those selected for a low proportion of nodes branching. The same applied to selections for earliness of nodal branching. In attempts to improve stolon growing point density in pastures, selection for internode length is likely to be more successful than selections for proportion of nodes branching and earliness of branching.