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Species composition of ryegrass ( Lolium perenne ) and tall fescue ( Festuca arundinacea ) mixtures using various combinations of n ‐alkanes
Author(s) -
Cortes C.,
Damasceno J. C.,
Bechet G.,
Prache S.
Publication year - 2005
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.2005.00473.x
Subject(s) - lolium perenne , alkane , festuca arundinacea , composition (language) , zoology , chemistry , festuca , biology , agronomy , hydrocarbon , poaceae , organic chemistry , linguistics , philosophy
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 C 29 ‐ and C 31 ‐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 C 29 ‐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.