Application of 2,4-dichlorophenoxypropionic acid 2-ethylhexyl ester reduces mature fruit abscission in Citrus navel cultivars

Summary

2,4-dichlorophenoxyacetic acid (2,4-D) isopropyl ester has been used extensively, since the 1950’s, to reduce mature fruit abscission in Citrus navel cultivars. However, this synthetic auxin is no longer registered for this purpose in the European Union (EU). 2,4-dichlorophenoxypropionic acid (2,4-DP) 2-ethylhexyl ester has been registered in the EU for use in citrus growing and can be an effective replacement for 2,4-D to reduce pre-harvest fruit abscission. Use of the 2-ethylhexyl ester of 2,4-DP sprayed before mature fruit abscission significantly reduced fruit drop in sweet orange (Citrus sinensis L. Osbeck) ‘Washington navel’ and ‘Navelate’. The magnitude of the response depended on the concentration applied. At 15 mg l^–1, the percentage of abscised fruit was reduced by 50–75% compared to untreated trees, depending on the variety and the orchard. Increasing the concentration applied to 50 mg l^–1 did not improve this response. The response to this auxin was as effective as that obtained with 2,4-D applied on the same day at the same concentration (15 mg l^–1). 2, 4-DP treatment had no effect on skin colour or on the internal and external characteristics of the fruit at harvest.     

The role of ethylene in abscission of sweet orange promoted by exogenous application of the abscission agent 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP)

Mature ‘Valencia’ fruit were treated with 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP), and the ethylene inhibitors aminoethoxy vinyl glycine (AVG) and silver thiosulfate (STS), to assess involvement of ethylene in abscission via CMNP. Fruit detachment force (FDF) and ethylene evolution were measured over time. Accumulation of the ethylene precursor 1-aminocyclopropane-1-carboxylate (ACC) in peel upon CMNP application was assessed and impact of application of ACC on FDF was estimated when applied 1 cm away from the abscission zone (AZ), to determine its potential as a signaling molecule in promoting fruit loosening. CMNP when applied alone reduced FDF by 50%. AVG and STS inhibited fruit loosening considerably at 500 µM and 10 mM, respectively, when applied with 2 mM CMNP. ACC accumulation in peel was highest 2 days after CMNP application, which preceded the maximum decline in FDF which occurred a day later, indicating that ACC serves as a potential signaling molecule that triggers abscission in the AZ. The results of the study support the hypothesis that abscission via CMNP application is at least partly ethylene dependent. However, the decline in FDF by ACC was less than 50% of control which suggested involvement of another pathway in abscission via CMNP in sweet orange.     

Reducing preharvest drop of ‘Temple’ orange fruits by 2,4-D — Role of cellulase in the calyx abscission zone

One or two treatments of 2,4-D (18 p.p.m.) applied to ‘Temple’ orange trees during the last 6 weeks before the regular picking-period in late January, successfully reduced natural preharvest fruit abscission, allowing picking to be delayed by at least one month, and thus producing better external and internal fruit quality. It has been demonstrated for the first time that the delaying effect of auxin treatment on preharvest abscission was directly related to the decrease in the activity of endo- and exo-cellular cellulase. Most of the increase in cellulase activity during the abscission process was, however, due mainly to the activity of exo-cellular cellulase. When frost occurred a few days after application of 2,4-D, the auxin treatment significantly decreased total cellulase activity, thus reducing fruit abscission.The data proved that, except for the difference in the length of time between application and the onset of the hormone effect, the control mechanism of 2,4-D on abscission and on cellulase activity in intact fruit is similar to that previously reported for fruit explants.     

Methyl jasmonate plays a role in fruit ripening of ‘Pajaro’ strawberry through stimulation of ethylene biosynthesis

The role of methyl jasmonate (MJ) in strawberry (Fragaria × ananassa Duch. cv Pajaro) fruit ripening was investigated by monitoring its endogenous concentrations in fruit at various stages of development and the effects of exogenously applied MJ at these stages on ethylene biosynthesis. The concentration of endogenous trans-MJ was significantly higher in the white fruit (31.7–162.2 ng g⁻¹) and decreased sharply in half and fully ripe fruit. Higher concentrations of endogenous trans-MJ at the white stage of strawberry fruit development followed by a decline during fruit ripening indicate that MJ may play an important role in modulating fruit ripening. Significantly increased ethylene production was measured in the fruit when MJ was applied at white, half ripe and at fully ripe stage. The application of MJ (50 μM) resulted in significantly highest ethylene production and increased activities of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase as compared to all other treatments. The effect of exogenously applied MJ on ethylene production, ACC synthase and ACC oxidase activities was dependent on concentration of MJ applied and on fruit developmental stage. In conclusion, MJ in strawberry modulates fruit ripening, as its concentration is higher in white fruit and is declined with the progression of ripening and exogenous application of MJ increases ethylene production, activities of ACC oxidase and ACC synthase depending upon the concentration of MJ applied and fruit developmental stage.     

Effects of valsartan alone or in combination with benazepril on blood pressure and left ventricular hypertrophy in spontaneously hypertensive rats

AIM:To evaluate the effects of different doses of valsartan alone or with concomitant be-nazepril on blood pressure,left ventricular hypertrophy,RAASfunction and endoxi nlevel in spontaneously hy-pertensive rats(SHR).METHODS:Thirty SHR(fourteen-week-old,male)were divi ded into five groups(six rats in each group):SHR control group:fed with normal saline;benazepril group:fed with 1 mg·kg^-1·d^-1benazepril);low dose valsartan group:fed with 8 mg·kg^-1·d^-1valsartan;high dose valsartan group:fed with 24 mg·kg^-1·d^-1valsartan;combination drug therapy group:fed with valsartan(8 mg·kg^-1·d^-1)and benazepril(1 mg·kg^-1·d^-1),all for 8 weeks.WKY control group(n=6):fed with normal saline for 8 weeks.RESULTS:SBP,LVM/BW,TDMof SHR were remarkably lower than those of control after drug i n-tervene,and effect on SBP was most remarkable in high dose valsartan group and i nthe combi nation drug ther-apy group;effect on LVM/BW,TDM were most remarkable in combination drug therapy group.Renin activi-ties in plasma and myocardiumwere remarkably i ncreased in drug i ntervene groups.The levels of AngⅡi nplasma and myocardiumwere remarkably increased in two different dose of valsartan treati ng group,and thelarger dose of valsartan were,the higher levels of AngⅡin plasma and myocardium were;decreased in be-nazepril treati ng group and combination drug therapy group.Na⁺-K⁺-ATPase activities in myocardi umwere remarkably i ncreased and the level of endoxi n i n myocardium were remarkably decreased as SBP de-creased after drug intervene.CONCLUSION:Different dose of valsartan alone or combi ned with benazeprilcan decrease SBP of SHR,have the effect of inhibiti ng progression of ventricular hypertrophy.The effect ofcombination drug therapy group was most remarkable among five groups and can avoi d the si de effect of highAngⅡin plasma and myocardiumduri ng long-termuse of valsartan alone.     

An increase in citrus fruit (Kiyomi tangor) abscission induced by ABA is accompanied by an IAA increase in the abscission zone and ethylene production

Summary

Change in IAA concentrations in the peduncle, branch and intervening abscission zone were measured to clarify the involvement of IAA in citrus fruit drop in response to ABA application. Results indicating the importance of an IAA increase in the abscission zone were obtained. One day after application of ABA, the concentration of IAA in the abscission zone showed a temporary increase and then a decrease. The concentration of IAA in the abscission zone was dependent on the concentration of ABA applied. Changes in the production of ethylene, which is involved in the process of abscission and which is induced by IAA, in explants from treated leafy inflorescences, were examined. The fruit-abscission ratios were also investigated in relation to the time required for preparation. Explants sampled 0±1.d after application showed little abscission or ethylene production during the first 24 h incubation. During the next 24 h, almost all the ABA-applied explants abscinded, as did the control, but the former produced 3±4 times more ethylene. ABA-applied explants, sampled 2.d after application, abscinded and produced ethylene markedly during the first 24.h, whereas the control explants did not abscind. Control and ABA-applied explants, sampled 3 d after application, showed no differences in their abscission ratios and ethylene production. These findings indicate that a temporary IAA rise in the abscission zone, observed one day after application, is involved in ethylene production in ABA-induced citrus fruit drop.     

Gibberellic acid and fruit set in sweet orange

A single GA₃-spray at petal-fall to the entire tree enhanced initial set in the ‘Navelate’ sweet orange (Citrus sinensis L. Osbeck), but this effect was transient and in most cases final yield was not increased. When followed by girdling, final yield was increased even in the most productive orchards, this effect being due to an increase in fruit number while fruit size was unaffected. The response was markedly dependent on the GA₃ concentration, 5 mg l^?1 giving the best results. Higher concentrations up to 20 mg l^?1 even reduced yield compared to the untreated control trees. Chlormequat reduced the number of fruits finally cropped without affecting their size, an effect which may be explained through a reduction in the endogenous gibberellin levels.     

Influence of salicylic acid and methyl jasmonate on glucosinolate levels in turnip

Summary

The effects of the elicitors, salicylic acid (SA) and methyl jasmonate (MJ), on glucosinolate levels and composition were assessed in turnip plants. Data on glucosinolate levels in leaves, secondary roots, and primary roots of hydroponically-grown turnip are presented. Treatment with either elicitor increased the total amount of glucosinolates, particularly levels of the aromatic 2-phenylethyl- and indole-glucosinolates, in secondary roots. In contrast, SA or MJ either reduced or did not affect the levels of aliphatic glucosinolates. These results suggest that application of SA or MJ induced the biosynthesis of aromatic and indole glucosinolates in turnip, indicating a strategy for the production of plants rich in these substances, which could be used as raw material for the production of functional foods, nutraceuticals and pharmaceuticals.     

Sugar changes in Clementine and orange fruit during ripening

Summary

Juice and rind sugar content, fruit volume and rind colour were determined in cvs Fina, Oroval and Hernandina Clementines and in cvs Navelina, Washington Navel and Navelate oranges, cultivars that are harvested at different periods during the season. An accumulation of sugars was observed in all cultivars during ripening, mainly due to an increase of sucrose in the juice and of reducing sugars in the rind. Cv Hernandina, a late Clementine, showed a slower rate of sugar increase in rind.     

荔枝ACS1基因的分离及其与幼果脱落的关系

【目的】植物中ACC合成酶(ACC synthase,ACS)和ACC氧化酶(ACC oxidase,ACO)是调控乙烯形成的关键酶。荔枝ACO基因已分离获得,在此基础上,笔者进一步从荔枝中分离出ACS基因,进而分析该基因与荔枝幼果脱落的关系。【方法】通过RT-PCR和RACE扩增技术相结合的方法分离荔枝ACS基因;利用遮阴、环剥摘叶和100 mg·L-1NAA处理促进荔枝幼果脱落,进而用实时荧光定量PCR分析荔枝ACS基因与幼果脱落的关系。【结果】首次从荔枝中分离出ACS基因,命名为Lc-ACS1。Lc-ACS1推导的氨基酸序列与多种植物的ACS蛋白有较高的同源性,其中与甜橙和蓖麻的同源性最高,为76%。该基因包含ACS基因特有的11个不变氨基酸残基和7个保守区。遮阴、环剥摘叶和100 mg·L-1NAA处理都可以显著促进荔枝幼果脱落,且环剥摘叶后幼果乙烯释放量高峰出现在第2天。Lc-ACS1基因在任何一种促进荔枝幼果脱落过程中的表达量都高于对照,且基因表达量的高峰都早于相对落果率高峰。【结论】LcACS1基因可能是调控荔枝幼果脱落中的关键基因。     

适宜山东阳信栽培的梨早熟和中熟品种

对近年引进的18个梨早、中熟新品种的外观和内在品质、耐贮性及市场前景等进行综合评定认为,早熟品种伏宝(暂定名)、玛瑙、绿宝石梨,中熟品种晚秀、圆黄、黄冠梨等6个品种适宜阳信栽培。简要介绍了该6个品种在阳信的主要性状表现。     

A combination of gum arabic and chitosan can control anthracnose caused by Colletotrichum musae and enhance the shelf-life of banana fruit

Summary

Anthracnose, caused by Colletotrichum musae, is the major disease affecting the quality of banana fruit during storage. To control banana anthracnose, the combined effects of coatings with gum arabic [GA; at 5, 10, 15 or 20% (w/v)] and 0.75% (w/v) chitosan (CH) were investigated and compared to untreated controls. In vitro results showed significant (P < 0.05) inhibition of mycelial growth and conidial germination of C. musae in all combined treatments compared to the untreated controls after 7 d of incubation at room temperature (25°C). However, potato dextrose agar (PDA) plates amended with 10% (w/v) GA gave the most promising results among all test treatments in suppressing mycelial growth (86%) and inhibiting conidial germination (80%), while no effective inhibition of conidial germination was observed in the controls. In vivo results confirmed that 10% (w/v) GA was the optimum concentration to control fruit decay (70%), while showing efficacy on the reduction of growth of C. musae on artificially inoculated banana fruit. The combined coatings of GA + CH also significantly delayed ripening in terms of weight loss, fruit firmness, soluble solids content, and titratable acidity. These results support the possibility of using 10% (w/v) GA combined with 0.75% (w/v) CH as an alternative strategy to control post-harvest anthracnose disease in banana fruit.     

Hormonal regulation of physiological leaf spot and premature leaf abscission in ‘Golden Delicious’ apple trees

Exogenous growth substances (GA₄₊₇, IAA, PBA, and ABA) alone and in combination were applied as leaf dips to young ‘Golden Delicious’ apple trees in a growth room at 21 °C. All treatments containing GA₄₊₇ accelerated the incidence of physiological leaf spot over treatments without GA₄₊₇, ABA alone delayed the appearance of leaf spot. PBA, PBA + GA₄₊₇, and PBA + GA₄₊₇ + IAA retarded the abscission of spotted leaves.GA₄₊₇ and GA₄₊₇ + PBA also accelerated leaf spot development in bearing ‘Golden Delicious’ trees in the orchard.Fumigation of apple trees with ethylene at 2, 10, and 20 ppm had no influence on the occurrence of leaf spot or premature abscission.     

Problems seeded in the past: lagged effects of historical land-use changes can cause an extinction debt in long-lived species due to movement limitation

Landscape Ecology - Land-use change is one of the main threats to biodiversity on the global scale. Legacy effects of historical land-use changes may affect population dynamics of long-lived...     

Antioxidant activity and oxygen-scavenging system in orange pulp during fruit ripening and maturation

The antioxidant activity (ferric reducing/antioxidant power, FRAP) and oxygen-scavenging system of pulps during the fruit ripening and maturation were investigated in three cultivars of sweet orange (Citrus sinensis (L.) Osbeck). The highest FRAP values and activities of antioxidant enzymes and contents of nonenzymes were detected in ‘Red Flesh’ navel orange. The activities of oxygen-scavenging enzymes, superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (G-POD), decreased with ripening and maturation of fruit. Ascorbate peroxidase (AsA-POD) and dehydroascorbate reductase (DHAR) activities were also stably declined, whereas glutathione reductase (GR) activity and nonenzymes in the ascorbate–glutathione cycle displayed a single-peak pattern which paralleled the significant changes in FRAP values. In addition, the ratios of ascorbate/dehydroascorbate (AsA/DHAsA), reduced glutathione/oxidized glutathione (GSH/GSSG) were also decreased. Changes in the activities of antioxidant enzymes and the contents of nonenzymes during ripening indicated that the antioxidant system plays a fundamental role in the ripening of orange fruits.     

‘脐橙52’山地果园优质丰产栽培技术

‘脐橙52’具有生长势较强、适应性良好、丰产优质的特点。山地果园栽培应以搞好水土保持、改善土壤结构为重点,协调根部与地上部平衡生长,以延长果树的经济收益期。定植密度宜先密后疏,既提高土地利用率,又可获得早期产量效益。成年树修剪采取冬剪和夏剪相结合,早施稳果肥,第2次生理落果后及时疏果,提高果实的整齐度。生物防治病虫害,开展果林结合、果牧结合、草生栽培等生态型果园管理模式。     

橘红心黄瓜类胡萝卜素的积累与变化规律探究

为研究橘红心黄瓜果实类胡萝卜素积累过程及变化规律,以橘红心水果黄瓜和旱黄瓜为研究对象,以与其生长习性类似的普通黄瓜为对照,利用分光光度计法对上述材料的类胡萝卜素含量分别进行测定,并利用RHS植物比色卡对各材料瓤色进行比较分析。试验结果表明,不同黄瓜材料的类胡萝卜素含量存在显著差异。其中材料‘JHH-3’在果实发育40 d时类胡萝卜素质量分数高达252.95 mg·L~(-1),而从果实瓤色看,当果实发育40 d时材料‘JHS-1’和‘JHH-3’瓤色最深,说明黄瓜果实瓤色与类胡萝卜素含量存在正相关。而在众多材料中材料‘JHS-3’转色最早,材料‘JHS-1’次之。     

An innate cholinergic system and its regulation in mature dendritic cell

AIM:To investigate whether there was nicotinic acetylcholine receptor subunit α 7(nAChR α 7), choline acetyltransferase(ChAT), acetylcholinesterase(AChE) expression and its regulation in mature dendritic cells(DCs). METHODS:Bone marrow(BM)-derived DCs from healthy BALB/c mice were incubated with rmGM-CSF and rmIL-4, and stimulated to mature with LPS. Meanwhile, light microscope and flow cytometry were used to identify DCs, as well as immunocytochemistry, immunofluorescence, flow cytometry and RT-PCR methods were used to dectect expression of nAChR α 7,ChAT and AChE. Flow cytometry was also used to analyze nAChR α 7 expression with mecamylamine (MEC) in 12 h. RESULTS:Both protein and mRNA expression of cholinergic system nAChR α 7，ChAT and AChE were found in mature DCs. Furthermore, nAChR α 7 distributed principally in cell membrane, while ChAT and AChE in cytoplasm. Protein expression of AChE was stronger as compared with ChAT (P<0.05), and there was a trend toward increasing as compared with nAChR α 7. And then, the expression of nAChR α 7 was down regulated by MEC as compared with the group without MEC stimulation(P<0.05). CONCLUSION:An innate cholinergic system was in mature DCs， which was affected by extrinsic factor (i. e., MEC). And it may be involved in anti-inflammation immune adjustion of cholinergic closed-circuit.     

壳聚糖与有益微生物组合的生物保鲜剂用于丰都红心柚常温贮藏试验

丰都红心柚系从丰都县实生普通红心柚混杂群体中选育出的中熟红柚新品种,以其果肉色泽红艳,汁多化渣,酸甜可口,无核无异味的优良品质深受消费者青睐,多次评为部、省优质果品,2001年获中国名牌产品殊荣.迄今,已建生产基地4800km^2,部分柚园已试投产,年产果近万吨.为延长市场供应期和缓解成熟期过于集中所造成的种种压力,对其进行贮藏保鲜仍然是最有效的途径.但随着病原菌抗性逐渐增强以及消费者对果品质量安全要求不断提高,人们日益关注化学防腐保鲜剂的潜在危害,开发天然的、无公害高效的生物保鲜剂已越来越受到科技工作者的重视并取得显著成效.本试验是对高分子质量壳聚糖进行降解,形成更具生理活性的低分子质量壳聚糖（夏文水,1998）,并与有益微生物适当组合,配制成发挥二者功能的新型生物保鲜剂,用于丰都红心柚常温贮藏条件下防腐保鲜.     

桂林市宽皮柑桔的生产现状、存在问题及发展探讨

根据桂林市宽皮柑桔的生产现状，分析生产上存在的一些问题，提出今后一段时间内桂林市宽皮柑桔的发展思路、目标及对策。