Cucurbit Genetics Cooperative Report 7:35-36 (article 16) 1984

Optimum Plot Size for Once-over Harvest of Pickling and Fresh- market Cucumbers

T.C. Wehner and W.H. Swallow

North Carolina State University, Raleigh, NC 27695

An efficient method for measuring yield in cucumbers is to count the fruit number in small plots harvested once-over. This can be done with both pickling and freshmarket cucumbers, and is a useful predictor of yield in multiple-harvest as well as once- over harvest conditions (Wehner and Miller, unpublished data). Optimum plot size for once-over harvest of pickling cucumbers has been estimated to be 1.5 x 2.4 m, based on data from cultivar yield trials (2). However, we wished to estimate optimum plot size for both pickling and fresh-market cucumbers using data from uniformity trials where only one cultivar of each type was tested, and to compare estimates from different fields and years. Furthermore, we wished to compare optimum plot sizes under conventional once-over harvesting methods with those under new labor-saving techniques for simulating once-over harvest using paraquat to defoliate the plots before evaluation. The objective of this study was then to estimate optimum plot size for pickling and fresh-market cucumbers grown in uniformity trials in 1982 and 1983 using labor costs for both conventional hand-pulled plots and herbicide-defoliated plots.

Methods. The experiment was planted at the Horticultural Crops Experiment Station near Clinton, North Carolina, on July 22, 1982, and May 23, 1983. Rows were seeded on raised, shaped beds 1.5 m apart center to center using 'Calypso' and 'Slicemaster' as the pickling and fresh-market cucumber cultivars, respectively. Plots were thinned to 15 plants at the first-leaf stage. Rows were harvested in 1.5 m increments and the total number of fruit counted in each plot on September 2 and 9, 1982, and on July 12 and 14, 1983, for pickling and fresh- market cucumber plots, respectively. For each year and crop, optimum plot size for judging yield as number of fruit per plot was determined by the method of Smith (1), using estimated costs (man-hours required) to conduct the trial with either conventional (hand-pulled plots) or herbicide-defoliation (paraquat) methods.

Results. The number of man-hours required to perform each operation in conventional and herbicide-defoliated yield trials is shown in Table 1; for both methods the greatest labor costs were in planting and harvesting. Estimates of optimum plot size when costs were taken into account are given in Table 2. The 1982 and 1983 estimates of optimum plot size for pickles, and the 1983 estimate for fresh-market cucumbers, were in close agreement and recommend small plots, about the size of the basic 1.5 x 1.5 m unit used in this experiment. The 1982 fresh-market estimate of optimum plot size is much larger; of the 4 plantings this one had the least variable yield data, but there was little correlation between yields of neighboring plots, so larger plots became worthwhile. The conventional (hand-pulled plots) method, being more labor-intensive, had smaller optimum plot size than the herbicide-defoliated (paraquat) method for all crops and years.

Literature Cited

1. Smith, H.F. 1938. An empirical law describing heterogeneity in the yield of agricultural crops. J. Agr. Sci. 28:1-23.
2. Smith, O.S. and R.L. Lower. 1978. Field plot techniques for selecting increased once-over harvest yields in pickling cucumbers. J. Amer. Soc. Hort. Sci. 103:92-94.