Attributes related to seasonal herbage growth in white clover
When breeding temperate forage species is investigated, some attributes such as herbage accumulation and seasonal growth patterns have to be considered. To modify some of these traits, knowledge of the detailed process might be useful. In order to evaluate seasonal growth of contrasting white clover populations an experiment was carried out. Treatments were five cultivars and three local populations collected in Argentina. Weekly measures were taken during each season to calculate leaf appearance and flower appearance rates, stolon growing rate and dry matter (DM) net accumulation. Different germplasm of this species have different mechanisms for DM accumulation. Leaf size, more than leaf appearance rate, was the variable with most differences among germplasm and mostly related to dry matter accumulation. During spring and summer, inflorescences production had important effects on growing stolon rate, and differences among germplasm were evident. Some local populations showed favourable attributes that could be useful for breeding.
Effects of cultivar and cutting frequency on dynamics of stolon growth and leaf appearance in white clover grown in mixed swards
The hypothesis that dynamics of growth, branching of stolons and appearance of leaves are important for the persistence of white clover (Trifolium repens) in mixed swards was tested. The effect of cutting frequency and white clover cultivar on stolon and leaf dynamics was studied throughout the growing season in a field experiment. Mixtures of perennial ryegrass (Lolium perenne) and white clover cultivars with different leaf sizes, cvs. Alice, Gwenda and Retor, were evaluated for white clover persistence at two cutting frequencies. Stolon dynamics, stolon survival, leaf and node appearance rate, branching, flowering and stolon elongation rate were analysed and related to white clover content and yield. There were clear seasonal fluctuations in stolon and leaf characteristics. Stolon elongation rate and appearance rates of nodes, leaves and branches declined in autumn. Temperature and irradiation explained a major part of the variation of stolon elongation rate and leaf appearance rate and 25% of the variation in stolon branching rate. Significant and consistent differences in yield and botanical composition were found between mixtures. Mixtures with cv. Alice had the highest total and white clover yield and the highest white clover content, whereas mixtures with cv. Retor had the lowest yield and the lowest white clover content. Stolon elongation rate and stolon internode length were significantly higher in cv. Alice than in the other white clover cultivars, whereas cv. Retor had a significantly higher percentage of leaves with damage caused by insects and slugs than the other cultivars. Little support was found for the hypothesis that branching characteristics are a key component of competitive success in mixed pasture, as most measured branching characteristics were not associated with differences in white clover yield between cultivars and cutting regimes.
Morphological variation among white clover (Trifolium repens L.) populations collected from a range of moist hill country habitats
Abstract Genotypes of white clover were collected from a range of hill country habitats defined by aspect, slope, fertiliser input, management, and stock class, and grown as spaced plants in a uniform environment. Few morphological differences were found among genotypes that could be related to habitat of origin. However, genotypes from rotationally grazed cattle pastures were taller than those from rotationally grazed sheep pastures. Effects of fertiliser input level on plant height and on leaf/flower height ratio, and effect of slope on leaf and flower heights and growth, were inconsistent. Hill country genotypes had characters intermediate between ‘Grasslands Tahora’ and ‘Grasslands Huia’. Genotypes with (a) high and low proportions of nodes branching, (b) long and short internodes, and (c) large and small leaf sizes were selected and crossed in isolation. Comparison of progeny with parents showed that differences in nodal branching frequency and internode length observed in the field were environmenta...