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Field prediction of alfalfa ( Medicago sativa L.) fibre constituents in northern Europe
Author(s) -
Andrzejewska J.,
ContrerasGovea F. E.,
Albrecht K. A.
Publication year - 2014
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/gfs.12069
Subject(s) - medicago sativa , zoology , mathematics , agronomy , maturity (psychological) , latitude , mean squared prediction error , biology , statistics , geography , psychology , developmental psychology , geodesy
Models to predict neutral detergent fibre ( NDF ) and acid detergent fibre ( ADF ) of alfalfa before harvest have been developed in the USA , but have not been tested in northern Europe or above 50°N latitude. Our objective was to test predictive equations for alfalfa quality ( PEAQ ) and the New York prediction equation for alfalfa quality ( NYPQ ) for estimating alfalfa NDF and ADF in northern Poland. A total of 275 alfalfa samples, varying in height and maturity, were collected from twenty farm fields over 3 years. Observed NDF and ADF values were regressed on predicted values. The accuracy of PEAQ for predicting NDF and ADF in Poland was equal to that observed in the USA ( r 2 > 0·89; RMSE < 21·6). In most cases regression equations were not biased (slope = 1 and y‐intercept = 0), and when there was bias it was minimal. The relationship between observed and NYPQ prediction of NDF was also strong ( r 2 > 0·88; RMSE < 23·0), but these equations were extremely biased. The results demonstrate that the PEAQ model provides a simple, rapid and reasonably accurate means to estimate fibre concentrations of alfalfa before harvest, appropriate for the growing conditions of northern Europe.