title: Addressing huge spatial heterogeneity induced by virus infections in lentil breeding trials.
abstract: BACKGROUND
  Spatial heterogeneity can have serious effects on the precision of field experimentation in plant breeding. In the present study the capacity of the honeycomb design (HD) to sample huge spatial heterogeneity was appraised. For this purpose, four trials were conducted each comprising a lentil landrace being screened for response to viruses.
  
  
  RESULTS
  Huge spatial heterogeneity was reflected by the abnormally high values for coefficient of variation (CV) of single-plant yields, ranging 123-162 %. At a given field area, increasing the number of simulated entries was followed by declined effectiveness of the method, on account of the larger circular block implying greater intra-block heterogeneity; a hyperbolic increasing pattern of the top to bottom entry mean gap (TBG) indicated that a number of more than 100 replicates (number of plants per entry) is the crucial threshold to avoid significant deterioration of the sampling degree. Nevertheless, the honeycomb model kept dealing with variation better than the randomized complete block (RCB) pattern, thanks to the circular shape and standardized type of block that ensure the less possible extra heterogeneity with expanding the area of the block.
  
  
  CONCLUSIONS
  Owing to the even and systematic entry allocation, breeders do not need to be concerned with the extra spatial heterogeneity that might induce the extra surface needed to expand the size of the block when many entries are considered. Instead, they could improve accuracy of comparisons with increasing the number of replicates (circular blocks) despite the concomitant greater overall spatial heterogeneity.
authors.affiliation: Department of Agricultural Development, Democritus University of Thrace, 68200 Orestiada, Greece.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kargiotidou
authors.affiliation: Industrial and Fodder Crops Institute, Hellenic Agricultural Organization, 41335 Larissa, Greece.
authors.forename: Dimitrios N
authors.initials: DN
authors.lastname: Vlachostergios
authors.affiliation: Department of Agricultural Development, Democritus University of Thrace, 68200 Orestiada, Greece.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Tzantarmas
authors.affiliation: Industrial and Fodder Crops Institute, Hellenic Agricultural Organization, 41335 Larissa, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Mylonas
authors.affiliation: Industrial and Fodder Crops Institute, Hellenic Agricultural Organization, 41335 Larissa, Greece.
authors.forename: Chrysanthi
authors.initials: C
authors.lastname: Foti
authors.affiliation: School of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Menexes
authors.affiliation: School of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
authors.forename: Alexios
authors.initials: A
authors.lastname: Polidoros
authors.affiliation: Department of Agricultural Development, Democritus University of Thrace, 68200 Orestiada, Greece.
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Tokatlidis
keywords: Honeycomb method; Randomized complete block; Selection effectiveness