Even and Systematic Entry Arrangement of the Honeycomb Model to Cope with the Spatial Heterogeneity in Field Trials of Lentil Landraces.

Spatial heterogeneity is a common problem in field experimentation preventing objective genotype evaluation. The even and systematic entry arrangement of the honeycomb method has been asserted as an effective procedure to tackle the problem. The hypothesis was tested in three lentil (Lens culinaris L.) landraces, named ‘Elassona’ ‘Evros’, and ‘Lefkada’, grown at separate trials each including 1000 plants (area of 900m2). Huge spatial heterogeneity was recorded due to severe virus infection, depicted by the extreme CVs for single plant yields (123, 129 and 169%). It was hypothesized that the entire heterogeneity would have been controlled whether comparison of a number of simulated entries would not reveal significant residuals from the overall mean yield (t-test). Further, it was assumed that extreme spatial heterogeneity is hard to be absolutely controlled with increasing the number of entries dispersed on a certain area. Each experiment was analysed assuming that included 4, 7, 9, 12, 13, 16, 19 or 21 simulated entries. In general, the top to bottom gap of means increased with increasing the number of entries but this was not always true. For example, 13 rather than 12 entries substantially lowered this gap. In most cases no significant residuals existed, however, the number of those observed did not associated with the number of entries. For ‘Elassona’ just one and two residuals were significant for 19 and 21 entries, respectively. Significant residuals for ‘Evros’ were 1 (12 entries), 1 (16 entries) and 2 (19 entries), while for ‘Lefkada’ were 1 (12 entries) and 2 (21 entries). The conclusion was that, the triangular plant arrangement of honeycomb designs might be a viable option to sample the environmental heterogeneity; under extreme spatial heterogeneity however, it does not ensure absolute control, while the number of entries involved within an area does not seem crucial. This research has been co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) Research Funding Program: THALES. Investing in knowledge society through the European Social Fund.