Cucurbit Genetics Cooperative Report 10:25-26 (article 16) 1987
Genotype-Environment Interaction for Cucumber Yield
in 23 North Carolina Environments
Todd C. Wehner
Department of Horticultural Science, North Carolina State University, Raleigh,
Pickling and fresh-market cucumber cultivars are regularly tested for
fruit yield to determine their usefulness for growers in particular areas
of North Carolina. Plant breeders developing new cultivars for the state
need to know how many environments should be used in order to assure adequate
performance. Genotype-environment interaction provides an indication of
whether testing should be carried out at several different environments,
or if one is sufficient to represent the region(1).
Yield in a multiple-harvest trial can be estimated efficiently by counting
number of fruits per plot in a single harvest at the stage when 10% oversized
fruits are present (3, 4). Two or 3 replications of each entry provided
the most information for the resources expended.
The objective of this study was to determine the importance of genotypeenvironment
interaction for fruit yield using 23 combinations of years, seasons and
locations in North Carolina.
Methods. A random set of hybrids, inbreds, cultivars and experimentals
(referred to as genotypes hereafter) was tested in North Carolina for yield
and quality. The 44 genotypes were chosen to represent new and old, tall
and dwarf, resistant and susceptible (to southern foliar diseases), and
pickling and fresh-market types (22 genotypes each).
Plots were 25-plant rows 1.5 m long and 1.5 m apart seeded on raised
beds. The environments consisted of 2 years (1984, 1985), 3 seasons (spring,
summer, fall), 4 locations (Clayton, Clinton, Castle Hayne and a stress
field in Clinton), and 2 replications. The stress environment consisted
of heavier soil and only half the irrigation, fertilization and pesticide
applications given the main Clinton location. Data were analyzed for only
23 of the 24 environments tested, because the Fall-1984-Castle Hayne trial
was destroyed by a hurricane. Yield was measured as fruit number in a single-harvest
trial. Harvest was made when 10% of the fruits were oversized in the check
plots ('Calypso' for pickling and 'Poinsett 76' for fresh-market genotypes).
Results. Analysis of variance indicated significant mean squares
for genotype and environment, and for the interaction (GxE) of the two,
with the largest variances for environment. The GxE component was only 32
to 52% as large as the genotype component (Table 1). In a 2-season study
run at 1 location and year, Strefeler and Wehner estimated additive genetic
genotype and its interaction with environment in 3 fresh-market cucumber
populations. The ratio of GxE interaction to genotype ranged from 58 to
112% depending on population.
Since the ranking of cucumber genotypes changed significantly over the
North Carolina environments sampled in this study, plant breeders must test
in more than one environment for development of cultivars adapted to the
area. The next step is to determine how many environments are needed for
proper representation of the performance of North Carolina conditions.
Table 1. Variance components for yield in pickling and fresh-market cucumbers.z
** Indicates significant mean square at the 1% level according to F test.
z Estimates are from a test with 23 environments and 22 genotypes of cucumbers.
y Constants for estimation of variance component mean squares are g=22,
e=23, and r=2.
- Comstock, R.E. and R.H. Moll. 1963. Genotype-environment interactions.
In: W.D. Hanson and H.F. Robinson (eds.) Statistical genetics
and plant breeding. Nat. Acad. Sci., Washington, D.C., p.
- Strefeler, M.S. and T.C. Wehner. 1986. Estimates of heritabilities
and genetic variances of three yield and five quality traits in three freshmarket
cucumber populations. J. Amer. Soc. Hort. Sci.
- Wehner, T.C. 1986. Efficiency of 3 single-harvest trials for evaluation
of yield in pickling cucumber. Euphytica 35:493-501.
- Wehner, T.C. and C.H. Miller. 1986. Efficiency of single-harvest methods
for measurement of yield in fresh-market cucumbers. J. Amer. Soc. Hort. Sci. 109:659-664.