Direct Validation of AMMI Predictions in Turfgrass Trials

Ebdon, J S and Gouch, H G (2011) Direct Validation of AMMI Predictions in Turfgrass Trials. Crop Science, 51 (2). pp. 862-869.

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Abstract

Previous studies using turfgrass quality (TQ) data from the National Turfgrass Evaluation Program (NTEP) used cross validation with additive main effects and multiplicative interactions (AMMI) models to demonstrate accuracy gain within a single trial. The objective of this study is to test AMMI predictive accuracy for new years or new years × locations. Five winners recommended by the raw data AMMIF and five winners recommended by the more accurate AMMI5 model were selected, resulting in a 10-entry roster at six validation sites for evaluation over 5 yr. Average TQ for AMMI5 selections was 5.57 and was significantly greater than AMMIF selections averaging only 5.31. In five of six validation locations, higher TQ was observed by planting AMMI5 selections over AMMIF. The correlation between the 60 validation observations and AMMI5 predictions was 0.628 but for AMMIF was 0.479. Better predictive success indicated by a significantly lower mean squared deviation (MSD) was observed with AMMI5 (0.453) than AMMIF (0.608). The AMMI5 model predicted winners were five times as effective as AMMIF in predicting observed winners from the top group (rank one and two). There was decisive evidence of a parsimonious AMMI model increasing predictive success across years despite a meager 1.24 statistical efficiency with AMMI5.

Item Type: Article
Additional Information: The authors want to thank the National Turfgrass Evaluation Program for kindly providing data and for funding this research. They also appreciate the hard work of the NTEP cooperators in collecting the data. Paulo Annicchiarico and Kevin Morris provided valuable comments on an earlier draft of this paper. Martin Wells performed the bootstrap statistical test.
Author Affiliation: University of Massachusetts, Amherst(USA)
Subjects: Crop Improvement
Divisions: Other Crops
Depositing User: Mr. SanatKumar Behera
Date Deposited: 04 Jan 2012 03:16
Last Modified: 04 Jan 2012 03:17
Official URL: http://dx.doi.org/10.2135/cropsci2010.03.0158
URI: http://eprints.icrisat.ac.in/id/eprint/2881

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