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Abstract
Nineteen prior lists of new vegetable varieties introduced since 1936 were published in Vols. 63, 65, 67, 69, 70, 75, 77, 82, 84, 86, 88, 90 and 92 of Proceedings of the American Society for Horticultural Science, and Vols. 4(1), 5(3), 6(2) and 8(6) of HortScience. A compilation of list I through XV entitled Descriptive List of Vegetable Varieties was published jointly by the American Seed Trade Association, Inc. and the American Society for Horticultural Science in September 1972 and can be obtained from either organization.
The following abbreviations are used: exp. desig.-experimental designation; orig.-originated at or by; intr.-introduced by; par.-parentage or parents; char.-outstanding characteristics; res.-resistant to; tol.-tolerant to; sim.-similar to or resembles; sel.-selection or selected; adapt.-adapted to or adaptation.
Abstract
Apparent resistance of a treatment cv. as influenced by different surrounding cv. was measured in screening cucumbers for resistance to cucumber beetles and pickleworms. Degree and frequency of seedling damage, and percent seedling reduction were greater when ‘Zucchini Elite’ squash was the surrounding cv. than when any of 3 cucumbers were the surrounding cv. Significant differences in damage to seedlings were found among 9 cucumber cv. Two non-bitter cucumbers were among those least damaged by cucumber beetles; however, the frequency and degree of damage as measured by cotyledon feeding did not differ significantly from 1 of the bitter cv. Factors other than cucurbitacin content are probably involved in expressions of resistance to cucumber beetle. The surrounding cv. had no effect on pickleworm infestation. Pickleworm infestation was low in all cucumber cv. (1.4 per 100 fruit) when compared to summer squash (78 per 100 fruit). The value of ‘Zucchini Elite’ squash as a trap crop for pickleworm may be outweighed by the increased damage to seedling cucumbers by cucumber beetles when squash is the surrounding cv.
Abstract
Three F1 hybrids of cucumber (Cucumis sativus L.) and their inbred parents were grown at 2 day/night regimes (30°/20°C and 27°/14°) under controlled environment. Hybrids were superior in fresh weight under both temperatures at each of 2 stages of growth and had higher phenotypic stability than their parents.
Abstract
Parents, F1, F2, and backcross generations of a cross ‘Addis’ × ‘SMR 18’ were grown in a controlled environment with day/night temperature of 30°/20°C and a 15 hour photoperiod. Generation means for traits with significant differences were analyzed using an unweighted least squares procedure. An additive-dominance model accounted for most of the variation among generations for root, stem and total dry weight, shoot/root dry weight ratio, height, number of nodes and length of internodes. Some interallelic interactions were involved in the variation among generations for root and total plant fresh weight.
Abstract
A “gynoecious synthetic” (GS) population, developed by random mating of 50 adapted Cucumis sativus L. cultivars and breeding lines, and a “hardwickii semi-exotic” (HSE) population, developed by open-pollinating an F2 population derived from a cross between a Cucumis sativus var. hardwickii (R.) Alef. accession LJ 90430 and a gynoecious inbred line GY 14, were subjected simultaneously to S1 line (S1 and reciprocal full-sib (RFS) recurrent selection. S1 selection resulted in increased fruit number per plant in the GS and HSE populations, and in the GS × HSE population hybrid. In contrast, RFS selection did not result in increased fruit number per plant in the GS and HSE populations or their hybrid. The contrasting responses to S1 compared to RFS selection suggests that additive gene effects were more important than nonadditive effects in the expression of fruit number per plant. Correlated responses to selection resulted in increased number of days to harvest in the GS population, and in reduced percentages of gynoecious plants and pistillate flowers in the HSE population. No change in fruit firmness, and a reduction in length : diameter ratio of fruit only in the GS × HSE population hybrid developed through S1 selection, suggests that selection for increased fruit number per plant should not adversely affect these fruit quality characteristics in either the GS or HSE populations.
Abstract
Six crosses were made among eight cultivars and breeding lines of cucumber (Cucumis sativus L.). Within each cross 11 populations (including parents) representing 5 levels of heterozygosis were studied. Data were collected on fruit weight/plot, fruit number/plot, average fruit weight and fruit bearing index. Regression analysis was used to partition differences associated with levels of heterozygosis into linear, quadratic, and lack of fit components. With the exception of one cross, heterozygosis had significant positive effects on all characters. Linear responses of all populations to heterozygosis were highly significant for all characters in 5 of the 6 crosses. Incidences of significant quadratic and lack of fit mean squares were low. For all traits, with the exception of some instances of interallelic interactions, a genetic model based on cumulative action of independent loci with partial dominance explains differences associated with levels of heterozygosis.
Abstract
Six crosses were produced from 8 breeding lines and cultivars of cucumber (Cucumis sativus L.). Within each cross, 11 generations (P1, P2, F1, F2, F3, BC1 5 BC2, BC1×1, BC1×2, BC2×1, BC2×2) were studied. Data were collected on fruit weight/plot, fruit number/plot, average fruit weight and fruit bearing index at 2 locations. Preliminary analyses indicated the adequacy of an additive-dominance model for all characters in most crosses. The model was extended to include environment and genotype × environment interactions. The model was either significant or highly significant for all characters in all crosses. Dominance was a major contributing factor in the inheritance of all 4 characters. This was evidenced by significant dominance effects and substantial amounts of heterosis for all characters in most crosses. Such heterotic effects were large enough to justify the cost of hybrid seed production. Low incidences of dominance × environment interactions provided evidence for the stability of hybrids under different environments. Additive effects were significant for certain characters in some crosses. Significant additive effects suggested the effectiveness of selection for development of superior parental genotypes. Various degrees of additive × environment interactions were obtained. The interactions suggested that effective selection for yield should be carried out under more than one environment.
Abstract
Between and within F3, family variances were used to estimate the genetic variances for 3 yield characters in 6 crosses of pickling cucumber (Cucumis sativus L.). Significant additive and/or dominance variances were obtained for all characters in certain crosses. Significant additive variances suggested the effectiveness of selection for development of superior inbred lines, and significant dominance variances could be utilized in the production of hybrids. Fruit number contributes most to the commercial value of pickling cucumber, but selection for this trait will probably be effective if parthenocarpic gynoecious materials are used.
Abstract
Autotetraploid watermelons were produced by treating the growing points of diploid seedlings with aqueous colchicine solution or by soaking diploid seeds in colchicine solution. The soaking method was more effective.
Diploid pollen was apparently more viable than tetra-ploid pollen. Examination of germinating tetraploid pollen revealed that while over two-thirds germinated normally a small percentage sent forth 2, 3 or 4 normalsized pollen tubes or a single bifurcated tube. Germinating diploid pollen always put forth only one unbranched pollen tube. Tetraploid plants did not set fruit when pollinated with pollen from tetraploids; however, they did set fruit when pollinated with pollen from diploids.
Cytological observations were made of pollen mother cells of both diploid and tetraploid plants. Meiosis in diploids was regular; however, irregularities were observed in tetraploids. Examination of some pollen mother cells of tetraploids at the quartette stage revealed micro sporocytes in addition to the 4 microspores. The abnormal quartette formations and lower pollen viability of tetraploids were believed associated with irregularities observed at meiosis. Preliminary investigations of megaspore formation revealed no apparent differences between the diploid and tetraploid megaspores. Although meiotic irregularities were found, a sufficient amount of apparently viable pollen was observed. A physiological basis for the self-sterility is suggested.
Abstract
Three harvest methods and 3 plot sizes for estimating yields in pickling cucumbers (Cucumis sativus L.) were examined. The correlation between dollar values for a simulated once-over harvest and successive harvest were low (r < .16). Correlation between once-over harvest value and fruit number was .84, while correlation between once-over harvest value and mature fruit number was only .36. The correlation of .84 was high enough to warrant use of fruit number as a primary trait in selection for increased value. Use of fruit number as an estimate of yield would eliminate the grading and weighing processes needed to compute value. An efficient plot size for estimating mean differences between lines was 3.6m2.