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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, NC 27695-7609

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.

Literature Cited

  1. 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. 164-196.
  2. 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. 111:599-605.
  3. Wehner, T.C. 1986. Efficiency of 3 single-harvest trials for evaluation of yield in pickling cucumber. Euphytica 35:493-501.
  4. 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.
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Department of Horticultural Science Box 7609North Carolina State UniversityRaleigh, NC 27695-7609919-515-5363
Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 14 December, 2009