Effect of stage of ripening and ethephon treatment on color content of paprika pepper

In order to determine the proper time to harvest paprika pepper (Capsicum annuum L.) fruits to obtain maximum extractable color, two maturity indexes were evaluated. Most consistent results were obtained when fully shriveled fruits were harvested.Foliar applications of ethephon (50, 100, 200 and 500 ppm) were made on two cultivars, ‘Paprika-505’ and ‘Paprika-D.Z.’. Total extractable color and capsanthin content were determined using fully shriveled pericarp tissue. Some flower and leaf abscission was caused by treating plants with 500 ppm ethephon and leaves of plants treated with 200 or 500 ppm ethephon turned yellow. Ethephon stimulated ripening and increased the total extractable color and capsanthin levels of paprika fruits. ‘Paprika-505’ contained more total extractable color and capsanthin than ‘Paprika-D.Z.’ as a result of ethephon treatment.     

Production of fruits with attached flowers in zucchini squash is correlated with the arrest of maturation of female flowers

Summary

Results from two trials carried out under different environmental conditions indicated that the high temperatures reached in greenhouses during the Spring-Summer growing season are the main environmental factor inducing production of zucchini fruits with attached flowers. The fact that the incidence of this characteristic is genotypedependent, with the percentage of fruits with attached flowers varying from 1.4 – 73% among the different cultivars grown during the Spring-Summer season, provides an opportunity for direct counter-selection for this trait in current zucchini squash breeding programmes. High temperatures in the Spring-Summer growing season also induced male-ness in all the cultivars analysed, delaying the production of female flowers, and increasing the number of male flowers on the main stem. Indeed, those flowers that remained attached to harvested zucchini fruits were transformed into bisexual flowers, exhibiting different degrees of stamen development, and were arrested as immature, closed floral buds. A detailed analysis of the maturation and abscission times in female and male flowers of different zucchini cultivars indicated that, although abscission time did not differ, maturation time was longer in male than in female flowers. By comparing sexual expression in different cultivars in different environments, we concluded that inhibition of female flower bud maturation occurs concomitantly with a delay in flower abscission, a process accompanied by the conversion of the female bud into a bisexual bud. Given that Spring-Summer conditions promote the maturation of both female and male flowers, and that the arrest of female flower maturation and abscission are associated with floral sex determination, it is possible that the arrest of female flower maturation is not directly induced by high temperatures, but is mediated instead by hormones such as ethylene or gibberellins.     

Sensitivity of Geraldton waxflower to ethylene-induced flower abscission is reduced at low temperature

Summary

Exposure to ethylene gas elicits flower abscission from cut stems of Geraldton waxflower (Chamelaucium uncinatum Schauer). Ethylene response rates in plants are mediated by temperature. At 20°C, flower abscission from waxflower ‘Purple Pride’ occurred upon 12 h exposure to 1 µ11^–1 ethylene. This ethylene treatment did not cause flower abscission at either 10 or 2°C. Moreover, flowers held at 2°C were insensitive to 48 h exposure to 1, 10 and 100 µ11^–1 ethylene. However, increasing the duration of treatment with 1 µ11^–1 ethylene at 10 and 2°C to 48 and 144 h, respectively, induced flower abscission. When flowers were held at 20°C in air without exogenous ethylene following continuous exposure to 1 µ11^–1 ethylene at 2°C, the duration required to elicit flower abscission was reduced from 144 to 72 h. Collectively, these responses show that maintaining harvested waxflower at low temperature (e.g. 2°C) is an effective means to minimise ethylene-mediated flower abscission.     

Effect of sowing date on ethephon-caused feminization in muskmelon

Summary

Seeds of an andromonoecious muskmelon, cv. Piel de Sapo, were sown between the 5th and the 10th days of each month of 1986 and plants were kept in a glasshouse in Zaragoza (Spain). Plants were treated with 0, 150, 250 and 500 mgl^?1 ethephon solutions at three stages of development: two leaves, anthesis of the first male flower and anthesis of the first pistillate flower respectively. Plants sown in January, February, March and April achieved higher feminization rates than plants sown in May, June and July. Plants sown in September, October and November did not produce any pistillate flowers. When the plants were sown in December, the feminization rate was intermediate. When control plants had high feminization rates, treatments with 150 mg l^?1 ethephon solutions produced maximum feminization, while when these plants had low feminization rates, higher ethephon concentrations (250 or 500 mg l^?) were needed.     

彩椒保花保果剂配方及其应用效果

为了提高彩椒坐果率和降低畸形果率,以彩椒品种世季红为试材,研究3种配方保花保果剂对彩椒产量、坐果数和商品果率的影响,并在低温弱光照、亚适温弱光照和高温条件下比较最优配方在朝天椒、线椒和牛角椒上的应用效果。结果表明,喷施配方P_2(A液:复硝酚钠0.03 g·m L~(-1),B液:赤霉素0.10 g·m L~(-1)、2,4-D钠盐0.01 g·m L~(-1)、萘乙酸钠盐0.10g·m L~(-1))对彩椒保花保果效果最佳,小区产量、坐果数均显著高于对照,且商品果率和单果质量与对照无显著差异。在逆境条件下不同类型辣椒喷施配方P_2后,小区产量和坐果数均显著提高,商品果率和单果质量与对照无显著差异。综上,配方P_2能解决甜(辣)椒畸形果率与坐果率的矛盾且稳定性好,不同类型辣椒品种在不同逆境下均可应用配方P_2进行保花保果。     

Genetic improvement of vase life of carnation flowers by crossing and selection

We used conventional cross-breeding techniques to develop many carnation lines with long vase life and either low ethylene production or low ethylene sensitivity. Two cycles of selection and crossing to improve vase life led to a 3.6-day increase in mean vase life. All 39 selected lines had significantly longer vase life than the control cultivar, ‘White Sim’. In particular, second-generation lines 63-3, 63-12, 66-15, and 63-41 had a mean vase life of more than 15 days without chemical treatment. Measurements of ethylene production indicated that flowers of all second-generation selected lines had a greatly reduced capacity to produce ethylene. We screened three lines (515-10, 64-13, and 64-54) with low ethylene sensitivity. Evaluation by exposure to ethylene at high concentration showed that 64-13 and 64-54 were less sensitive to ethylene than ‘Chinera’, which is known for it low sensitivity. The vase life of these low-sensitivity lines was about twice that of ‘White Sim’. The extended vase life of selected lines was related to low ethylene production at flower senescence rather than to degree of ethylene sensitivity in young flowers. Ethylene sensitivity decreased with the age of the flower in many selected lines. The results clearly show that vase life of carnation flowers can be extended by crossing and selection.     

The Effects of Some Growth Regulators on Peach Flower Bud Abscission

Applications of growth regulators to detached peach laterals in winter had variable effects on flower bud abscission. GA₃ and GA₄₊₇ increased bud abscission while IAA, BA and ABA inhibited abscission. Ethephon had a variable effect. Interactions were obtained between the compounds generally with IAA or GA playing the major role. GA had a peak of activity during a critical period in late winter indicating a variation in responsiveness. Variations in sensitivity to GA were obtained for different cultivars. Field applications of GA₃, GA₄₊₇, and ethephon to Elberta peach trees in winter, alone and in various combinations, promoted bud abscission.     

Effect of Ethephon (2-Chioroethyl Phosphonic Acid) on Endogenous Levels of Auxins,Inhibitors and Cytokinins in Relation to Senescence and Abscission in Vicia Faba L.

Treating three cultivars of Vicia faba L. with ethephon led to reduced vegetative growth and enhanced abscission of leaves, flowers and immature pods. No clear pattern emerges of changes in the levels of endogenous auxin and inhibitors as a result of treatment with the growth regulator. Cytokinin levels in leaves of treated plants were much higher than in the controls but no changes occurred in stem tissue. The results are discussed in relation to senescence, abscission and flowering.     

乙烯对‘洛阳红’牡丹切花开放衰老进程及内源乙烯生物合成的影响

 以开花指数为1级的‘洛阳红’牡丹切花为试材,研究了外源乙烯和乙烯作用抑制剂1-甲基环丙烯（1-MCP）处理对其采后开花衰老进程中开花指数、花径增大率、瓶插寿命、内源乙烯生成量及乙烯生物合成关键酶ACC合成酶（ACS）和ACC氧化酶（ACO）活性的影响,从乙烯生物合成角度探讨了乙烯对其采后开花衰老的调节机理。结果表明,10 μL·L^-1乙烯处理6 h明显加快了‘洛阳红’花朵开放进程,缩短了切花的瓶插寿命,并促使其在盛开后出现严重落瓣;1.0 μL·L^-1 1-MCP处理6 h则延缓了花朵开放,延长了瓶插寿命,但却影响了部分切花的充分开放;内源乙烯的生成分别受乙烯和1-MCP处理的促进和抑制,与切花的开放衰老进程密切相关。不同处理后ACS、ACO酶活性分析表明,ACS活性变化与内源乙烯的生成相联系,是影响牡丹切花开放衰老进程的主要因子,这与目前得出的ACS是植物乙烯生物合成限速酶的研究结果相一致。     

纳米银对瓶插月季切花乙烯作用的拮抗效应

 以月季‘影星’（Rosa hybrida‘Movie Star’）切花为试材,用5、10和30 mg · L^-1纳米银（nano-silver,NS）溶液,0.5 mmol · L^-1硫代硫酸银（silver thiosulfate,STS）溶液和去离子水（对照）分别预处理花枝（长为25 cm）基端2 h后再移至去离子水中瓶插,之后用10 μL · L^-1外源乙烯处理24 h,观测切花瓶插期间的观赏品质,瓶插寿命,花径和花枝鲜样质量等指标的变化。结果表明：乙烯处理可加快切花失水凋萎及叶片脱落,并抑制花朵开放,而NS处理可显著减轻乙烯处理的不利影响,其中以30 mg · L^-1 NS处理效果最佳,该处理月季切花的瓶插寿命比乙烯处理延长7 d。另外,取月季切花的花朵（带5 cm花茎,无叶）进行上述试验,进一步证实乙烯处理可抑制花朵开放,而NS处理可显著减轻乙烯对花朵开放的抑制作用。     

Effects of temperature on fruit thinning with ethephon in ‘Golden Delicious’ apples

The effect of temperature on the ability of 2-chloroethylphosphonic acid (ethephon), when applied at 20 mm stage of fruit development, to induce ethylene evolution of fruit and leaves and abscission of fruit and leaves was determined using 9-year-old root-bagged ‘Golden Delicious’/M.27 apple (Malus domestica Borkh.) trees in environment-controlled growth rooms. Ethephon at 400 μL L⁻¹ effectively thinned apples, and its thinning effect was not affected by increasing day/night temperature from 21.1/10 to 32.2/21.1 °C. Fruit ethylene evolution was enhanced by application of ethephon. Peak fruit ethylene evolution occurred 1 day after application of ethephon when day/night temperature was 32.2/21.1 °C whereas it occurred 2 days after application of ethephon at a day/night temperature of 21.1/10 or 26.7/15.6 °C. Ethephon increased leaf ethylene evolution drastically but it did not induce leaf abscission regardless of temperature.     

Cuticular cracking in pepper fruit. I. Effects of night temperature and humidity

Summary

The objective of the present study was to characterize some of the anatomical and physiological characteristics of fruit cracking in bell pepper (Capsicum annuum L.). Scanning-electron micrographs show that initiation of fruit cracking in bell pepper is by formation of mini-cracks on the cuticle layer; these then enlarge into cracks and traverse the epidermal cells. Pepper cultivars differ in their sensitivity to cracking, partly because of differences in fruit pericarp thickness. Limitation of night transpiration by high humidity or low temperature increased the turgor potential of the fruit pericarp and enhanced cracking. Likewise, leaf pruning suppressed night transpiration and concomitantly increased cracking. Fruit cuticle transpiration was found to be low in the early stages of fruit development and to increase as the fruit became susceptible to cracking. Environmental conditions which enhanced cracking also increased cuticle transpiration in a sensitive pepper cultivar but not in a less sensitive one. We suggest that fruit cracking in bell pepper occurs because reduction in night transpiration causes high turgor pressure in the fruit. As the cuticle becomes permeable to water, the inner turgor pressure causes the cuticle to crack. Differences in cultivar sensitivity may be partly due to differences in pericarp thickness and cuticle properties, but additional factors may be involved.     

Abortion of reproductive organs in sweet pepper (Capsicum annuum L.): a review

Summary

Levels of abortion of reproductive organs (i.e., buds, flowers, and young fruits) in sweet pepper plants (Capsicum annuum L.) are high, and cyclical fluctuations occur in fruit set. Stages susceptible to abortion are very young buds (< 2.5 mm), buds close to anthesis, and flowers and fruits up to 14 d after anthesis. An overview of factors and processes involved in flower and fruit abortion in sweet peppers is presented. More light, higher CO₂ concentrations, and lower planting density, increase the availability of assimilates per plant, and decrease fruit abortion. The cyclical pattern in fruit set is caused by changes in demand for assimilates. High flower abortion occurs when fast growing fruit (at approx. 3 weeks after anthesis) are present, due to competition for assimilates. Fruit set increases when fast growing fruit are almost mature and have a low assimilate demand. Prior to abortion, auxin export from the reproductive organ diminishes, ethylene production increases, and lower levels of activity of sucrose-cleaving enzymes are found. Severe water stress and low nutrient supply also increase abortion levels. Low night- and high day-time temperatures hamper pollen development, causing low seed set, which can result in fruit abortion. Two theories have been used to explain abortion: unbalanced demand for and supply of assimilates, and hormonal dominance of developing fruit over young fruit. Attempts to prevent abortion or to diminish the cyclical pattern of fruit set have not yet been successful, but new suggestions are presented.     

Ethylene Production During Senescence of Flowers

A method of determining ethylene production by detached flowers is described. A surge of ethylene has been shown to accompany the wilting of carnation flowers at the end of senescence. This surge is independent of fungal infection and it is concluded that in the infected flower the major source of ethylene production is the host tissues.

A similar surge of ethylene production has been observed when the inflorescence wilts on the plant between 20 and 40 days from flower opening.

At temperatures above 7·2° C. (45° F.) the ethylene surge was accompanied by collapse of the petals and rapid loss of water. Cut flowers kept continuously below 7·2° C. slowly declined in weight, the petals became flaccid and ethylene production was negligible. Infection of the flowers with fungus did not materially alter the effect of temperature on the ethylene production.     

Post-harvest physiology of waratah inflorescences (Telopea speciosissima,Proteaceae)

The post-harvest development and senescence of cut waratah inflorescences (Telopea speciosissima R.Br.) held at 20° C is described. Individual flowers of the raceme opened and after 4 or more days the perianth abscised, wilted and changed color from bright red to blue-red. The end of vase life was defined as a readily discernible wilting and blueing of either flowers or of the bracts which subtend the inflorescence. During vase life the fresh weight, water content and anthocyanin concentration of both flowers and bracts decreased. Water uptake by the whole inflorescence decreased, the cumulative nett water loss increased and the fresh weight of the inflorescence decreased. Ethylene production by flowers increased to a maximum and then declined, while the low ethylene production by bracts slowly decreased. Vase life was extended from 7.9 to 11.7 days when the vase water was treated with chlorine bactericide (sodium dichloroisocyanurate, 25 mg l⁻¹ available Cl). This increased vase life was accompanied by increased water uptake, decreased nett water loss, and a slower rate of decrease in flower and bract fresh weight and water content. Vase life was also extended by early harvest, when 6% of individual flowers were open rather than 48%. It was concluded that decreased water uptake and flower abscission were the major physiological factors which limited vase life.     

The effect of micro-organisms on susceptibility to freezing-damage in petals of cut rose flowers

The susceptibility of cut rose flowers to freezing-damage at sub-zero temperatures was examined. A correlation was found between visible freezing-damage and electrolytic conductance of petal leachate; electrolytic conductance was therefore used to evaluate the extent of freezing-damage.Inoculation of flowers with microbial suspension rendered them more susceptible to freezing-damage. The antibiotic streptomycin reduced the susceptibility to freezing-damage of flowers inoculated with micro-organisms, but did not affect the susceptibility of freshly-cut, untreated flowers.The significance of these findings is discussed in relation to temperature management during storage of cut flowers. It is suggested that freezing-damage is influenced by the presence of bacteria which proliferate during later phases of flower development and act as ice nuclei in the flower.     

杏品种花器官耐寒性研究

以杏２５个品种的花朵为材料,在低温下,通过测定花蕾和盛开花的电解质渗出率,配以Ｌogistic方程,结合组织褐变观察,确定的杏花蕾和盛开花的ＬＴ50（半致死温度）与实际 观察结果基本一致,杏花蕾抗低温温度为－７～１１℃,盛开花朵抗低温温度为－３～－６℃。丙二醛含量和乙烯释放量与其抗寒性有关。     

Variation in the effects of ethephon on flowering and extension growth in chrysanthemum as a function of temperature,season, and genetics

Summary

Ethephon (2-chloroethylphosphonic acid), an ethylene-releasing agent, is used in the production of Summer-to-Autumn-flowering chrysanthemums (Chrysanthemum morifolium Ramat.) to avoid early budding under long-day conditions. This study was carried out to show the variation in response to ethephon due to temperature, season, and cultivar. The seasonality of growth and flowering capacities, growing temperatures, and the genetic background of chrysanthemum make the effects of ethephon unstable and variable. The most important factor modifying the effect was the response to temperature, which showed seasonal variation. Ethephon briefly suppressed extension growth and flowering after chilling and at high growing temperatures. On the other hand, it induced dormancy and rosette formation, and suppressed flowering after Summer, and at lower temperatures. This suggests that ethylene is involved in the induction of dormancy.     

乙烯处理对番茄离体小花柄脱落的影响

 以番茄‘辽园多丽’品种为材料, 比较花蕾期、开花期及幼果期的小花(果) 柄对乙烯诱导脱落的敏感性。结果表明, 开花期小花柄最易接受乙烯的诱导而脱落, 20μL·L ^-1乙烯是最佳诱导浓度。该浓度处理的小花柄在脱落后期, 各部位POD、CMC-Na 酶及E_xo-PG活性升高, 但不同部位的POD、CMC-Na酶、E_xo-PG活性及可溶性蛋白含量变化不一致。     

Promotion of floral initiation in ‘Fuerte’ avocado by low temperature and short daylength

Potted avocado (Persea americana Mill., cv. ‘Fuerte’) plants were maintained in growth cabinets for up to 32 weeks and new growth observed for flower formation. Flowers were formed if temperatures were 20°C or below, but with 25° or 30°, even if only for 1 hour per day, flower formation was inhibited. Time to flowering was accelerated, but number of flowers reduced, if daylength was shortened from 15 h to 9 h. With low temperature and short days, full bloom was about 4 months after starting experiments. Spring flowering of cv. ‘Fuerte’ in the field could follow flower induction about 4 months previously with the onset of winter temperatures and daylengths.