Interspecific hybridization in Cucumis (L.). I. Need for genetic variation,biosystematic relations and possibilities to overcome crossability barriers

Summary The genetic variation in pickling and slicing cucumbers (C. sativus L.) seems insufficient to enable the breeder to solve serious cultivation problems. Wild allies of C. sativus possess a wide range of interesting characters which could be incorporated by means of species crosses. In the past, attempts to achieve such crosses have failed. Important characters of Cucumis species are mentioned and biosystematic problems discussed. Results of previous research on species crosses prompted an examination of the prospects of further research.     

Detection of fruit fly infestation in pickling cucumbers using a hyperspectral reflectance/transmittance imaging system

Fruit fly infestation can be a serious problem in pickling cucumber production. In the United States and many other countries, there is zero tolerance for fruit flies in pickled cucumber products. Currently, processors rely on manual inspection to detect and remove fruit fly-infested cucumbers, which is labor intensive and also prone to error due to human fatigue and the difficulty of visually detecting infestation that is hidden inside the fruit. In this research, a laboratory hyperspectral imaging system operated in an integrated mode of reflectance and transmittance was used to detect fruit fly-infested pickling cucumbers. Hyperspectral reflectance (450–740 nm) and transmittance (740–1000 nm) images were acquired simultaneously for 329 normal (infestation-free) and fruit fly-infested pickling cucumbers of three size classes with the mean diameters of 16.8, 22.1, and 27.6 mm, respectively. Mean spectra were extracted from the hyperspectral image of each cucumber, and they were then corrected for the fruit size effect using a diameter correction equation. Partial least squares discriminant analyses for the reflectance, transmittance and their combined data were performed for differentiating normal and infested pickling cucumbers. With reflectance mode, the overall classification accuracies for the three size classes and the mixed class were between 82% and 88%, whereas transmittance achieved better classification results with the overall accuracies of 88–93%. Integration of reflectance and transmittance did not result in noticeable improvements, compared to transmittance mode. The hyperspectral imaging system performed better than manual inspection, which had an overall accuracy of 75% and whose performance decreased significantly for smaller size cucumbers. This research demonstrated that hyperspectral imaging is potentially useful for detecting fruit fly-infested pickling cucumbers.     

Optimum plot size determination and its application to cucumber yield trials

Summary Methods of estimating Smith's b and, thereby, optimum plot size are compared from a theoretical viewpoint. For estimating b, generalized least squares is recommended over Smith's (1938) original method and other methods because the points used to fit the required regression are correlated and have unequal variances.Optimum plot size for once-over-harvest trials measuring yield (as number of fruits per plot) of pickling and frest-market cucumbers (Cucumis sativus L.) was estimated to be 0.7 to 3.8 m² (0.5 to 2.5 m of row for rows 1.5 m apart) for conventional harvesting, and 1.0 to 5.6 m² (0.7 to 3.7 m of row) for simulated harvesting using paraquat to defoliate plots before evaluation. Estimates of optimum plot size were calculated from a number of uniformity trials differing in year (1982 or 1983), planting date (early or late), and field. The estimates were sufficiently stable to suggest that they have useful generality.For multiple-harvest yield trials, optimum plot sizes for determining yield of pickling (expressed in $/ha or q/ha) or fresh-market cucumbers (i.e. USDA Fancy and No. 1 grade fruit combined or USDA Fancy, No. 1, and No. 2 grade fruit combined, in q/ha) were estimated from experimental data to be 6.4 to 10.3 m² (4.3 to 6.8 m of row).     

Effect of end-border condition on small-plot yield of cucumber

Summary Twelve or 14 cultivars and breeding lines (collectively referred to as lines hereafter) of pickling and fresh-market cucumbers (Cucumis sativus L.) were evaluated in 1.5 m long plots. The plots were harvested once when the check lines reached the 10% oversized fruit stage, and total, marketable, and early (oversized) number of fruits per plot was counted. The plots were planted with or without 1.5 m long end-borders to determine whether end-borders can be eliminated in small-plot trials where seed numbers and field space are limiting. Yield in unbordered plots was inflated 5 to 21% over bordered plots, but there was generally no significant effect in the analysis of variance for line x end-border condition. Therefore, end-borders are not needed when comparing different lines.     

The breeding of scab-resistant frame cucumbers in the Netherlands

Summary Scab caused by the fungus Cladosporium cucumerinum, may cause serious damage to frame cucumbers. Bulbosan (trichlorotrinitrobenzene) is an effective chemical means of control. Between 1945 and 1954 this German fungicide could not be supplied, and, as a result, the need for resistant varieties became very great.Before 1920 scab-resistance in pickling cucumbers was already known to Dutch growers. Selection started around 1920 on the initiative of W. G. v. d. Kroft and resulted in scab-resistant pickling cucumbers of which Baarlose Nietplekker VI is still widely grown. In 1948 G. W. v. d. Helm (Exp. Garden at Sloten) started breeding a scab-resistant yellow slicing cucumber destined for gardeners in the neigh-bourhood of Amsterdam. The resistant variety Highmoor was used as one parent. In 1954 the yellow variety Vios and the white variety Mabro were introduced. In 1952 G. W. v. d. Helm at the Exp. Garden Sloten, and J. M. Andeweg at the Institute of Horticultural Plant Breeding, Wageningen, simultaneously started breeding green scab-resistant frame cucumbers, using Highmoor as the resistant parent. In 1955 the experimental garden at Sloten introduced the scab-resistant green slicing cucumbers Amato and Proso, while in 1956 the Institute of Horticultural Plant Breeding introduced the scab-resistant green slicing cucumber Esvier. In 1953 seed of 2 first-backcross populations was supplied by the Institute to seed growers. At present intensive breeding for scab-resistance is also being carried out by a number of Dutch seed growers.Scab-resistance depends on one dominant gene; and young plants can readily be tested for resistance. Consequently a backcross scheme can easily be carried out. Rapid breeding is possible because at least 2 cultures can be carried out yearly. If necessary, cuttings of promising plants can be taken. Before and after artificial pollination the flowers can be tied up with raffia. It is simpler, however, to pinch the flowers with a special stainless clip as originally used for grafting cucumbers.The uniform fruit colour of the Dutch green frame slicing cucumbers is a recessive character; the fruit length of the Dutch varieties is dominant.     

Gummy stem blight resistance of cucumbers (Cucumis sativus L.)

Summary A start was made with breeding for resistance to gummy stem blight in cucumber. A method has been development for screening plants in a young stage. Using this method a distinct level of resistance was found in plants of Leningradsky, Wjarnikovsky,a P.I. entry from Birma, Rheinische Vorgebirge and a P.I.entry from Turkey. Lines developed from this material show a higher level of resistance than Dutch slicing and pickling cucumber varieties.     

海胆和海参中microRNAs的研究进展

MicroRNAs(MiRNAs)是一种长度为20 nt左右的内源调控型非编码RNA,主要参与基因的转录后调控,在真核生物的生长发育、细胞分化和免疫防御等过程中发挥重要作用。海胆和海参属棘皮类动物,是高等的海洋无脊椎动物,它们不仅是研究无脊椎动物向脊椎动物进化的重要模式生物,其中的一些种类还是重要的渔业资源,具有较高的经济价值。近年来,探明各类miRNAs在海胆和海参生长发育及生理代谢过程中的调控功能及调控机制已逐渐成为海胆和海参研究领域的热点。本研究中综述了近年来海胆和海参中miRNAs的研究成果和相关进展,以期进一步丰富和完善海胆和海参中miRNAs的基础资料,为系统了解和掌握海胆和海参中miRNAs的序列特点、生物学功能及其参与调控重要生理过程的分子机制提供参考资料。     

Distribution center and retail conditions affect the sensory and compositional quality of bulk and packaged slicing cucumbers

During distribution and retail display, fruits and vegetables are often exposed to undesirable temperature and humidity conditions which often result in increased waste due to weight loss and objectionable appearance. Unwaxed fresh-market slicing cucumbers (cv. Calypso) were harvested from a commercial operation and shipped to a distribution center (DC) in Florida. At the DC, 2 d after harvest, cucumbers were sorted and either commercially machine packaged in expanded polystyrene trays covered with a polyvinylchloride film or remained unpackaged for bulk retail display. Cucumbers were transported the next day by truck to a retail store in Gainesville, collected from the store, and stored under optimum (10 °C and 90% RH) or simulated retail display conditions (4 °C or 14 °C and 90–92% RH). Sensory (visual and instrumental color, firmness, shriveling, chilling injury and decay) and compositional quality (pH, titratable acidity, soluble solids and chlorophyll contents) were evaluated initially at the DC and after a 4-d simulated retail display period. Overall, bulk cucumbers were softer, appeared more shriveled, and were more affected by pitting and decay than packaged cucumbers. Bulk cucumbers also appeared lighter green and more yellowish than packaged fruit. Hue angle was less in bulk than in packaged cucumbers, but no consistent differences were observed in the L*, chroma, and hue values between the different temperatures. Small variations in the L*, hue, and chroma values compared to significant losses in chlorophyll content suggest that insufficient chlorophyll degradation occurred to cause major visual color changes. The greater weight loss in bulk cucumbers compared to packaged fruit was associated with accelerated chlorophyll degradation, lower acidity, and lower soluble solids content. Although packaged cucumbers had better visual quality than bulk cucumbers, there was higher RH inside the packages and greater development of decay on packaged fruit. Overall, after the 4-d simulated retail display, the appearance of the cucumbers used in this study was considered to be objectionable due to either yellowing, loss of firmness, shriveling or decay, regardless of the treatment. Results from this study demonstrate the importance of using an appropriate protective package in addition to maintaining the optimum temperature during distribution and retail display. Moreover, initial quality evaluation should be performed upon reception at the DC, and before cucumbers are displayed at the retail store, in order to estimate the remaining shelf life before this product becomes unacceptable for sale.     

Water temperature for hydrocooling field cucumbers in relation to chilling injury during storage

The objective of this study was to test the hypothesis that water temperatures less than the lowest recommended storage temperature (10°C) for cucumbers could be used for hydrocooling without inducing chilling injury or negatively affecting storage life. Field cucumbers were hydrocooled with water at 1.5, 3.5, 6, 8 or 10.5°C until the internal cucumber temperature reached 12°C, or hydrocooled with water at 1.5°C until the internal cucumber temperature reached 1.7, 8 or 12°C. Cucumber temperature at harvest was ≈20°C and the storage temperature was 12°C. Little or no visual symptoms of chilling injury were observed after 10–12 days of storage. However, chlorophyll fluorescence measurements indicated some chilling stress at the membrane level in cucumbers hydrocooled with water at temperatures below 6°C and in cucumbers hydrocooled with water at 1.5°C until the internal product temperature was 1.7°C, as indicated by lower F_v/F_m values. Approximately one third of the cucumbers from all hydrocooling treatments developed rot. There were no significant differences in % marketable cucumbers or in % mass loss after 10 or 12 days of storage. These results suggest that cucumbers could be hydrocooled using water at temperatures below the recommended storage temperature of 10°C. However, it is not recommended to use water below 6°C or to cool the cucumbers below this temperature, due to increased risk of chilling injury as indicated by the chlorophyll fluorescence measurements.     

脱水对鲜切黄瓜贮藏品质的影响

采用两种脱水方式(自然沥干和离心脱水)处理鲜切黄瓜,通过电子鼻技术结合感官和品质分析对鲜切黄瓜贮藏期间的品质变化进行研究。结果表明:鲜切黄瓜在冷藏过程中稍有质量损失,果肉硬度下降,呼吸强度增加,离心脱水组黄瓜的品质整体劣于自然沥干组,菌落总数在贮藏6 d后大幅度增加,结合电子鼻PCA与LDA分析,自然沥干组在贮藏10 d、离心脱水组在贮藏6 d能够与其他贮藏时间有明显区别,可以推测自然沥干组的黄瓜切片货架期为8～9 d;而离心脱水组的切片货架期为4～5 d。     

Inheritance of parthenocarpy in pickling cucumbers (Cucumis sativus L.) and linkage with other characters

Summary The inheritance of parthenocarpy in the pickling cucumber has been studied with progenies of an incomplete diallel cross between lines with different degrees of parthenocarpy and with two sets of F₁, F₂ and B₁ of crosses between parthenocarpic and non-parthenocarpic lines. The inheritance of parthenocarpy could be explained by three independent, isomeric major genes with additive action, together with a non-allelic interaction of the homozygote-heterozygote type. Indications have been found for linkages between genes that govern parthenocarpy, femaleness and the spined/hairy fruit character. Consequences for breeding parthenocarpic varieties are discussed.     

Variation in the response of melon genotypes to sudden wilt

Summary Differences in the response of melon genotypes to the sudden wilt disease were observed in several field trials conducted during 1993–1994 in the Arava region of southern Israel. Generally, the disease was more severe in the late summer growing season which is shorter and has higher temperatures than the spring and autumn growing seasons. The Oriental pickling melon breeding line P6a was the most tolerant among the entries tested. The response to the disease was also studied using two segregating families and their progenitors. BSK (tolerant) × P202 (susceptible) and P6a (tolerant) × D17 (susceptible). Wilting percentages of F₁, F₂ and backcross families were intermediate between the parents, suggesting an additive mode of gene action.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

热处理对黄瓜LOX和PLD活性的影响

为了研究冷害温度(2℃)下PLD和LOX活性的变化规律,以黄瓜为研究对象,对其进行采后38,45和52℃ 30 min热水处理,测定2℃贮藏期间(15 d)黄瓜的细胞膜透性、丙二醛含量、PLD活性和LOX活性.结果表明:热水处理可以抑制果实细胞膜渗透率的升高,减少低温贮藏期间丙二醛的积累,降低黄瓜低温贮藏过程中PLD及LOX的活性,且以45℃、30 min热水处理效果最显著.     

施硒对‘荷兰86-13’和‘月脂’黄瓜品质影响

为研究施硒浓度对黄瓜硒含量及品质的影响,以‘荷兰86-13’黄瓜和‘月脂’黄瓜为试验材料,采用叶面喷施方法对黄瓜硒含量、维生素C、可溶性糖、可溶性固形物、有机酸等品质进行研究。结果表明,硒含量随施硒浓度的增加而增加。施硒浓度7.5 g/hm2的‘荷兰86-13’黄瓜维生素C含量增长显著,可溶性固形物含量增长率为22.22%,钾含量增长率为27.16%;施硒浓度7.5 g/hm2的‘月脂’黄瓜维生素C含量提高了8.2%,可溶性糖含量提高了12.98%,钾含量降低率达32.06%,施硒处理对其有机酸、蛋白质、粗纤维和钙含量影响不显著。因此,适当的施硒浓度可以显著提高黄瓜的维生素C、可溶性糖、可溶性固形物等品质,但施硒处理对于‘月脂’黄瓜对钾的吸收表现为抑制作用。     

Changed sex expression and possibilities for F1-hybrid seed production in some cucurbits by application of Ethrel and Alar (B-995)

Summary Experiments were performed to study the effects of the ethylene releasing compound Ethrel on sex expression in cucumbers and squash, and of Alar (B-995) plus Ethrel in muskmelons. As a result of foliage sprays with one or both of the above compounds normally monoecious plants produced female flowers only, for the first 2–3 weeks of flowering. The optimum treatments for cucumbers were two foliage sprays with Ethrel 250 ppm or 500 ppm applied at the second and the fourth true leaf stages. The optimum treatments for squash were Ethrel 250 ppm and 500 ppm applied at the first and the third true leaf stages.High doses (1000 ppm) or repeated applications of Ethrel retarded growth of muskmelons and cucumbers. Applications of B-995 (5000 ppm) plus Ethrel (500 ppm) at the second true leaf stage inhibited male flowering for 2–3 weeks of the flowering period. F₁-hybrid seeds of muskmelons were experimentally produced in large isolation cages in the field, using two monoecious lines as female parents. The merits and some of the problems associated with the production of F₁-hybrid seeds by the above methods are discussed.     

Efficiency of early generation testing in pickling cucumber

Summary Early testing was evaluated for efficiency as a procedure for selecting among lines for yield (total and marketable fruit number), earliness and fruit quality (shape, color and seedcell size) in 24 sets of lines developed at random from a pickling cucumber (Cucumis sativus L.) population. The advantage of early testing was calculated using the regression of S₆ on S₁ performance. The amount of effort required in worker-hours and the theoretical gain from selection were also considered in estimating the advantage of early testing. Early testing for specific combining ability and for general combining ability was up to 2.05 times as efficient as late testing for total yield, and up to 2.29 times as efficient as late testing for earliness. Early testing was not efficient for selection for the fruit quality traits measured, nor for inbred performance per se.     

A Modified Clean Production Technique of Recovering Calcium Phosphate for Gelatin Plant

A clean production technique, which can reduce wastewater pollution for gelatin plant in pH, suspended COD and Ca 2+ , has been proposed. Precipitated the lime from lime wastewater produced by lime process, then this alkali water without lime is added to another acidic wastewater produced by pickling process to e CaHPO 4. But in traditional technique, the lime wastewater with lime is added to pickling wastewater directly, little lime wastewater was consumed and large amount of lime wastewater, which contains high pH, high-suspended COD and high Ca, and is difficult to treat by biological treatment, is produced for gelatin plant. It is proved by the experiment that the final wastewater produced by the clean production technique has lower pH for the pickling wastewater consuming large amount of lime wastewater. It has lower COD for all the suspended COD and partial soluble COD being separated from the wastewater absorbed by CaHPO4 sedimentation, and that it has lower Ca for it is no longer the saturated lime solution.     

Efficiency of 3 single-harvest tests for evaluation of yield in pickling cucumber

Summary Three rapid tests for measuring yield (small plots harvested once-over, and single plants harvested at the green and at the mature fruit stage) of pickling cucumber (Cucumis sativus L.) were evaluated for efficiency compared with the standard multiple-harvest trial with 2 or 3 replications and large plots. Fifteen genotypes were tested in 1981 and 18 in 1982 to determine the correlation among the 4 methods. In 1981, single plants were tested at 4 densities to evaluate the effect of using spaced or crowded plantings in selecting for yield. The spaced and crowded plantings were less efficient than the standard density, but none of the single-plant tests run in 1981 or 1982 were more efficient than the standard method in measuring yield. The most efficient method was 1, 2 or 3 replications of small-plots harvested once-over at green fruit stage, with 160% more gain from selection expected than for the replicated, multiple-harvest trial.     

不同砧木嫁接白皮黄瓜的综合效应研究

试验分别以黑子南瓜、荆州南瓜、十堰南瓜、鄂西南瓜、天门葫芦作砧木嫁接白皮黄瓜 ,以自根苗作对照 ,对它们的生长发育情况、产量及抗病性进行了研究。结果表明 ,不同砧木嫁接苗的枯萎病发病率都极显著低于自根苗 ;黑子南瓜、荆州南瓜、十堰南瓜砧嫁接苗生长势始终优于自根苗 ,而鄂西南瓜砧的生长势始终与自根苗的相当。天门葫芦砧嫁接苗生长势前期优于对照 ,后期明显不如对照 ,出现了生理不亲和的特征 ;除鄂西南瓜砧外 ,其它砧木嫁接苗的开花结果比自根苗早 ,且前期产量显著高于自根苗。黑子南瓜、荆州南瓜砧嫁接苗的总产量显著高于自根苗 ,而鄂西南瓜和天门葫芦砧的总产量分别比自根苗的降低了 7 2 %和 2 6 5 %。十堰南瓜砧的总产量与对照差异不显著。从综合效应考虑 ,黑子南瓜、荆州南瓜是白皮黄瓜嫁接的理想砧木 ,十堰南瓜次之 ,鄂西南瓜嫁接效果不好。天门葫芦可作为白皮黄瓜早春大棚栽培的嫁接砧木。