Species composition of ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) mixtures using various combinations of n-alkanes |
| |
Authors: | C Cortes† J C Damasceno† G Bechet S Prache |
| |
Institution: | Unitéde Recherches sur les Herbivores, INRA Clermont-Ferrand/Theix, 63122 St-Genès-Champanelle, France;, and Departamento de Zootecnia, Universidade Estadual de Maringá, Avenida Colombo, 5790, Maringá, Paraná, Brazil |
| |
Abstract: | This study was conducted to evaluate the reliability of the n‐alkane technique for estimating the species composition of Lolium perenne (ryegrass, L) and Festuca arundinacea (tall fescue, F) mixtures. Samples of L and F were collected in May (period 1) and June 2003 (period 2) on mono‐specific swards that were maintained at a height of 9 cm. Seven sets of mixtures containing controlled proportions of L and F were then prepared: 1·00:0, 0·80:0·20, 0·60:0·40, 0·50:0·50, 0·40:0·60, 0·20:0·80 and 0:1·00 of L:F, respectively, in the mixture. The proportion of each species in the mixtures was estimated from measured n‐alkane concentrations, and then compared with the actual known proportion. Various n‐alkane combinations were tested and compared to establish which combination gave the best estimate. Total n‐alkane concentrations, and especially C29‐ and C31‐alkane concentrations, were higher in period 1 than in period 2 for both species. The best n‐alkane combination varied between periods, as did the effectiveness of C29‐alkane in discriminating between L and F. The species composition of the mixtures was satisfactorily estimated for the majority of n‐alkane combinations, providing the combination included n‐alkanes with contrasting profiles between both species. A systematic overestimation of the proportion of ryegrass was observed for the 0·50:0·50 mixture. |
| |
Keywords: | botanical composition n-alkanes ryegrass tall fescue |
|
|