Interference in monocultures and mixtures of orchardgrass (Dactylis glomerata L.) and timothy (Phleum pratense L.)

Madhukar Vishwanathrao Potdar
1986
Interference among plants involves responses of plants to their environment as modified by the presence and/or growth of neighbouring plants. An important theme of research on plant interference is the relationship between plant population density and measures of plant growth or agricultural yield. An experiment on plant interference was performed in which plots of two important forage species, orchardgrass (Dactylis glomerata L.) and timothy (Phleum pratense L.), were grown at different total
more » ... at different total population densities and mixture proportions. Measures of plant growth and yield were taken at five separate harvests during one growing season. The analysis of variance indicated that primary and derived measures of growth and yield generally were strongly affected by the three main experimental factors: time, total population density and mixture proportions. Best subset multiple regression analysis, using Mallow's CP criterion, helped to define which experimental factors and interactions were related closely to plant responses. Both of these analytical methods indicated that the main effects of experimental factors were often significant, while interactions among factors were less prominent. The best subset models were different in structure for different response variates, however, indicating that plant responses varied when different measures of growth were considered. Models were developed which provided an effective description of yield-density responses in monocultures and mixtures when interference was strong. Model parameters were used to compare the relative strengths of intraspecific and interspecific interference in each species. The higher-yielding species, timothy, exerted stronger interference, both within and between species than orchardgrass. Interference was significant early in growth and intensified with increasing population density. The parameters of the yield-density models were also used to assess differential yield responses in the mixtures. Net overyielding occurred in most mixtures because overy [...]
doi:10.14288/1.0302339 fatcat:ytvxnkx5yvddha5tjnl2bfsrgm