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.
A CONCISE TABLE FOR PATH ANALYSIS STATISTICS
A concise format for presenting path analysi statistics is demonstrated in which the path cefficients are placed in the main diagonal of amatrix, and the indirect effects are placed as off-diagonal elements. This arrangement makes it easier to compare within and among path analyses than with the currently used format, thus facilitating interpretation
Detailed studies of grazed swards — techniques and conclusions
Traditional methods of botanical analysis, such as the measurement of species composition by harvests of biomass and herbage separations, by counts of population density or by point quadrat procedures, have long been used in studies of grazed swards (e.g. Jones 1967). The measurements were made primarily to describe the nature of the resource being studied and to quantify responses. In the 1960s, the need for more detailed measurements of the components of growth of grass swards was advocated (Evans et al. 1964; Jewiss 1966; Silsbury 1970). It was argued that improved understanding of the mechanisms involved in responses to environmental and management factors would lead to improved efficiency of production. It will also enable prediction of the effects of management on the sustainability of sward productivity, sward floristic composition and animal performance. In these more detailed studies, in addition to traditional methods of botanical analysis, measurements are incorporated on individual plants or plant units (such as grass tillers). The additional measurements are made to characterize the morphological and physiological aspects of sward state and/or the rates of component processes of sward dry matter turnover, such as leaf and tiller birth and death rates, leaf extension and the frequency and extent of defoliation of individual species. This review of techniques is concerned with these additional measurements; it is not meant to be exhaustive and concentrates on above-ground measurements on individual plants/plant units in temperate perennial swards. For a comprehensive and up-to-date review of the wider range of sward measurement procedures, the reader is referred to Davies et al. (1993). The techniques will be described under three heads covering different aspects of study: (i) the inherent growth characteristics of the plant species, (ii) competitive relationships among species, and (iii) plant-animal interactions. Inherent growth characteristics of plant species