Interpreting treatment x environment interaction in agronomy trials

Citation
M. Vargas et al., Interpreting treatment x environment interaction in agronomy trials, AGRON J, 93(4), 2001, pp. 949-960
Citations number
21
Categorie Soggetti
Agriculture/Agronomy
Journal title
AGRONOMY JOURNAL
ISSN journal
00021962 → ACNP
Volume
93
Issue
4
Year of publication
2001
Pages
949 - 960
Database
ISI
SICI code
0002-1962(200107/08)93:4<949:ITXEII>2.0.ZU;2-5
Abstract
Multienvironment trials are important in agronomy because the effects of ag ronomic treatments can change differentially in relation to environmental c hanges, producing a treatment X environment interaction (T X E), The aim of this study was to find a parsimonious description of the T X E existing in the 24 agronomic treatments evaluated during 10 consecutive years by (i) i nvestigating the factorial structure of the treatments to reduce the number of treatment terms in the interaction and (ii) using quantitative year cov ariables to replace the qualitative variable year. Multiple factorial regre ssion (MFR) for specific T X E terms was performed using standard forward s election procedures for finding year covariables that could replace the fac tor gear in those T X E terms, Subsequently, we compared the results of the final MFR with those of a partial least squares based analysis to achieve extra insight in both the T X E and final MFR model, The MFR model with a s tepwise procedure used in this study for describing the T X E showed that t he most important interaction with year was that due to different N fertili zer levels and the most important environmental variables that explained ye ar X N interaction were minimum temperatures in January, February, and Marc h and maximum temperature in April. Evaporation in December and April were important covariables for describing year X tillage and year X summer crop interactions, whereas precipitation in December and sun hours in February w ere important for explaining the year X manure interaction, We also discuss the parallels with extended additive main effect and multiplicative intera ction analysis. Biological interpretation of the results are provided.