Factors affecting imazalil and thiabendazole uptake and persistence in citrus fruits following dip treatments.

The effect of concentration, temperature, and length of treatment with imazalil (IMZ) and thiabendazole (TBZ) was studied with application to citrus fruit. The amount of residues retained by fruit after "home" washing was also monitored. IMZ uptake in citrus fruit was related to treatment duration, whereas TBZ residues was not. Residues of IMZ or TBZ fungicides were significantly correlated with dip temperature (r = 0.943 for IMZ; r = 0.911 for TBZ). Treatment at 50 degrees C produced a deposition approximately 8 and approximately 2.5 times higher than when treatments were carried out at 20 degrees C in IMZ and TBZ, respectively. No significant differences in terms of IMZ deposition were detected after treatments carried out alone or in combination. Uptake of the two fungicides was associated with their physicochemical characteristics as well as different formulation types. IMZ residues showed a great persistence during storage when applied separately, and >83% of active ingredient was present after 9 weeks of storage. IMZ residues increased with dip length, doubling when dip time increased from 0.5 to 3 min. In contrast, TBZ residues did not change with the different dip times. Following postharvest dip treatments of citrus fruit at 20 or 50 degrees C, home washing removed approximately 50% of the IMZ and approximately 90% of the TBZ.     

Residue levels and effectiveness of pyrimethanil vs imazalil when using heated postharvest dip treatments for control of Penicillium decay on citrus fruit

The influence of fungicide concentration and treatment temperature on residue levels of pyrimethanil (PYR) in comparison with the commonly used fungicide imazalil (IMZ) was investigated in orange fruits following postharvest dip treatments. The dissipation rate of PYR residues was recorded as a function of storage conditions. The fungicide efficacy against green and blue molds caused by Penicillium digitatum and Penicillium italicum, respectively, was evaluated on different citrus varieties following the fungicide application at 20 or 50 degrees C. Residue levels of PYR in Salustiana oranges were significantly correlated with the fungicide dosage, but residue concentrations were notably higher (ca. 13-19-fold) after treatment at 50 degrees C as compared to treatments at 20 degrees C. After treatment at temperatures ranging from 20 to 60 degrees C, PYR and IMZ residues in Salustiana oranges were significantly correlated with dip temperatures. Dissipation rates of PYR during storage were negligible in both Salustiana and Tarocco oranges. Results obtained on wounded, noninoculated Miho satsumas revealed that when treatments were performed at 50 degrees C, PYR or IMZ concentrations needed to achieve the complete control of decay were 8- and 16-fold less than by treatment at 20 degrees C. When fruits were inoculated with either P. digitatum or P. italicum, the application of 400 mg L(-1) PYR at 20 degrees C or 100 mg L(-1) PYR at 50 degrees C similarly reduced green and blue mold development. These results were corroborated by storage trials on Marsh grapefruits and Tarocco oranges. The lowest concentration of PYR required to achieve almost total protection of the fruit against decay accounted for 100 mg L(-1) at 50 degrees C and 400 mg L(-1) at 20 degrees C, respectively. Treatments did not affect fruit external appearance, flavor, and taste. It is concluded that postharvest PYR treatment represents an effective option to control green and blue mold in citrus fruit and that integration of fungicide applications and hot water dips may reduce the possibility of selecting fungicide-resistant populations of the pathogen, as a consequence of increased effectiveness of the treatment.     

Orthophenylphenol and phenylhydroquinone residues in citrus fruit and processed citrus products after postharvest fungicidal treatments with sodium orthophenylphenate in California and Florida

Sodium orthophenylphenate (SOPP) has been used extensively for >40 years to control postharvest diseases of citrus fruits. Studies of the metabolism of [(14)C]SOPP have identified orthophenylphenol (OPP) as the major metabolite with phenylhydroquinone (PHQ) as a minor metabolite. The whole-fruit tolerance in the United States for OPP is 10 ppm. This study was conducted to quantify terminal OPP and PHQ residues in whole Navel oranges, grapefruit, and lemons following SOPP applications at maximum application rates and following commercial application and fruit storage practices. OPP and PHQ residues also were determined in products processed from treated Navel oranges. OPP residues in lemons, Navel oranges, and grapefruit treated with SOPP using foamer wash and shipping wax applications remained below the 10 ppm tolerance, and PHQ residues were all < or =0.439 ppm. PHQ residues in whole fruit increased with time in commercial storage. OPP residues in all Navel orange matrices except oil remained relatively stable with time in commercial storage; residues in oil declined substantially while in storage.     

Control of postharvest diseases of fruit by heat and fungicides: efficacy, residue levels, and residue persistence. A review

Extensive research has been done in recent years to reduce the heavy dependence on chemical fungicides to control postharvest diseases and disorders of horticultural crops. Alternative strategies were based on improved cultural practices, biological control, plant-defense promoters, and physical treatments such as UV illumination, radiofrequency treatment, heat therapy, and storage technologies. Among these, postharvest heat treatments such as hot water dips, short hot water rinsing and brushing, and hot air conditioning have reduced rot development and enhanced fruit resistance to chilling injury in sensitive cultivars while retaining fruit quality during cold storage and shelf life. Additive or synergistic increases in effectiveness were observed by integrating heat therapy with various chemical compounds, thus leading to significant reductions in the application of active ingredients to protect produce from decay. This paper highlights the knowledge on this topic with emphasis on heat therapy effects and factors affecting the uptake, persistence, and performance of fungicide residues when they are applied in combination with hot water.     

Residue level, persistence, and storage performance of citrus fruit treated with fludioxonil

The potential of postharvest dip treatments with fludioxonil (FLU) (a synthetic analogue of the bacterial metabolite of pyrrolnitrin), in controlling postharvest decay caused by Penicillium digitatum and Penicillium italicum of citrus fruit was investigated in comparison with the conventional fungicide imazalil (IMZ). The ultrastructural changes of fruit epicuticular wax was investigated as a function of water dip temperature, and the possible role of these changes was related to residue accumulation under FLU treatment. Residues retained by fruit were determined as a function of fungicide concentration, dip temperature, and fruit storage conditions. Scanning electron microscopy analysis revealed that fruit dipping in water at 30 or 40 degrees C did not cause differences in cuticular wax's ultrastructure in comparison to control fruit, while treatments at 50, 55, or 60 degrees C caused the disappearance of wax platelets, resulting in relatively homogeneous skin surface, due to partial "melting" of epicuticular wax. Residues of FLU in fruit treated at 20 or 50 degrees C were significantly correlated with the doses of fungicide applied. When equal amounts of fungicide were employed, the residue concentrations were notably higher (from 2.6- to 4-fold) in fruit treated at 50 degrees C than in fruit treated at 20 degrees C. The dissipation rate of FLU in "Salustiana" and "Tarocco" oranges was lower in fruit subjected to treatment at 50 degrees C. The minimal FLU concentration for almost complete decay control in artificially wounded fruit during 7-d storage at 20 degrees C was 400 mg/L active ingredient (ai) in fruit treated at 20 degrees C and 100 mg/L ai in fruit treated at 50 degrees C. Results on nonwounded Tarocco oranges subjected to 3 weeks of simulated quarantine conditions at 1 degrees C, plus 6 weeks of standard storage at 8 degrees C and an additional two weeks of simulated marketing period (SMP) at 20 degrees C revealed that almost complete decay control with FLU applications of 100 mg/L at 50 degrees C and 400 mg/L at 20 degrees C resulted in ca. 0.8 mg/kg FLU fruit residues, in agreement with results on wounded citrus fruit. When equal concentrations and temperatures were applied, FLU treatments were as effective as IMZ. In vitro trials showed a low sensitivity to FLU against P. digitatum and P. italicum isolates. MIC values for the complete inhibition of mycelium growth were >or=100 microg/mL, while ED(50) values ranged from 0.1 to 1 microg/mL for P. digitatum and from 1 to >100 microg/mL for P. italicum. The latter result suggests that care should be taken to avoid exclusive application of FLU in a sustainable program for management of fruit decay. However, integrating fungicide application and hot water dip may reduce the possibility of selecting fungicide-resistant populations of the pathogen, by increasing the effectiveness of the treatment.     

Simple and rapid determination of thiabendazole,imazalil, and o-phenylphenol in citrus fruit using flow-injection electrospray ionization tandem mass spectrometry

A simple and rapid analytical method for thiabendazole (TBZ), imazalil (IMA), and o-phenylphenol (OPP) in citrus fruit has been developed by using flow-injection electrospray ionization tandem mass spectrometry for the first time. The method involves the combined use of stable isotopically labeled internal standards (thiabendazole-(13)C(6), imazalil-d(5), and p-phenylphenol-d(9)) and a multiple reaction monitoring technique. The average recoveries for the fungicides at the tolerance levels (TBZ and OPP, 10 mg/kg; IMA, 5 mg/kg) ranged from 77 to 101%, with the coefficients of variation (CVs) ranging from 0.7 to 4.2% (n = 5). At half the tolerance levels (TBZ and OPP, 5 mg/kg; IMA, 2.5 mg/kg), the average recoveries ranged from 62 to 112%, with the CVs ranging from 0.7 to 8.4% (n = 5). The CVs of the average recoveries, obtained from lemon samples fortified with three fungicides at the tolerance levels, obtained on three different days over two weeks, ranged within 2%. The analysis time, including sample preparation and determination, is only 15 min.     

Residue levels and storage decay control in Cv. Star Ruby grapefruit after dip treatments with azoxystrobin

Cv. Star Ruby grapefruit (Citrus paradisi Macf.) were subjected to a 3-min dip in water at room temperature (20 degrees C) or at 50 degrees C with or without 25, 50, or 100 mg/L azoxystrobin (AZX). Then, the fruits were subjected to cold quarantine at 2 degrees C and 90-95% relative humidity (RH) for 3 weeks and then stored for 5 weeks at 8 degrees C and approximately 85% RH and for another 2 weeks at 20 degrees C and 80% RH to simulate a 2-week marketing period (SMP). No AZX residues were detected in the albedo and pulp following treatments at 20 or 50 degrees C, the total amount of residues being recovered from the flavedo tissue. There was a relationship between the AZX uptake in fruit and the amount of fungicide employed at 20 or 50 degrees C. When AZX was applied to the fruit at 25 mg/L at 20 degrees C, the residue level averaged 0.11 mg/kg (active ingredient, whole fruit basis). This residue concentration increased by 50 and 75% when the application rate increased from 25 to 50 or 100 mg/L, respectively. A similar pattern of accumulation was detected in fruit subjected to treatments at 50 degrees C. However, treatments at 50 degrees C produced residue levels higher than the treatments at 20 degrees C, with increases ranging from 63 to 84%, for the same concentration. Storage conditions did not affect the amount of AZX residues in the fruit. Treatment at 50 or 100 mg/L at 20 degrees C reduced the incidence of moderate to severe chilling injury (CI). Water dips at 50 degrees C reduced the incidence and severity of CI to a very low extent, with no additional advantages when hot water was used in combination with AZX. Treatments with 50 or 100 mg/L of AZX at 20 degrees C produced beneficial effects in decay control similar to those of 25 mg/L AZX at 50 degrees C or hot water alone. Better results were achieved with 50 or 100 AZX at 50 degrees C, providing complete control of decay during cold storage and with negligible decay after SMP. It was concluded that when AZX was applied at 50 degrees C, low doses of fungicide and minimal residue levels in fruit were required to control the postharvest decay of grapefruit. This treatment does not impair fruit quality and offers very interesting prospects for large scale application, due to the reduced potential toxicity of AZX to nontarget organisms and to the environment.     

高氧处理抑制草莓果实采后腐烂与抗病性诱导的关系

为探索高氧处理抑制果实腐烂与抗病性诱导的关系,本试验研究了60%和100% O₂及空气处理对草莓果实在5℃15 d冷藏及后续20℃空气中1 d货架存放期间果实腐烂和抗病相关酶活性变化的影响。结果表明,高氧处理能有效抑制草莓冷藏期间果实腐烂的发生,诱导总酚含量的增加,提高苯丙氨酸解氨酶、多酚氧化酶、几丁质酶、β-1,3-葡聚糖酶活性。经高氧处理冷藏15 d后的草莓果实在转移至20℃空气中1 d货架存放期间,果实腐烂仍受到明显抑制,同时保持较高的总酚含量和较高的苯丙氨酸解氨酶和多酚氧化酶活性。100% O₂对腐烂的抑制作用大于60% O₂处理。这些结果表明,高氧抑制草莓果实的腐烂与抗病相关酶活性的升高密切相关,抗病性诱导是高氧抑制草莓果实腐烂的重要原因。     

Factors affecting the synergy of thiabendazole, sodium bicarbonate, and heat to control postharvest green mold of citrus fruit

The efficacy of thiabendazole (TBZ) to control postharvest decay caused by Penicillium digitatum of citrus fruit can be enhanced by co-application with sodium bicarbonate (SBC) and/or heat treatment. The impact of these treatments was investigated in citrus fruit, as a function of TBZ and SBC concentration and temperature, and were related to the amount of TBZ residues in fruit (total residues), in fruit surface, in the cuticular wax, and in the inner fruit. The residue levels of TBZ were determined in 'Valencia' oranges following a 1 min dip in an aqueous mixture of SBC at 0.5, 1, or 2 wt %/vol and TBZ at 600 or 400 mg/L (active ingredient, a.i.) at 20 or 40 degrees C and after 0 and 20 days at 17 degrees C and 90% relative humidity. The influence of SBC and heat on the TBZ residue concentration on the fruit surface, in cuticular wax, and on the inner cuticle tissue was determined in 'Salustiana' oranges after a 1 or 3 min dip in TBZ alone at 600 mg/L and 20 or 50 degrees C or for 1 min in TBZ at 600 mg/L and SBC at 2% and 20 degrees C. The efficacy of heat treatments with water, SBC, and TBZ, applied separately or in combination, was investigated on artificially inoculated 'Nova' mandarins and 'Valencia' oranges for the control of postharvest green mold caused by a TBZ-sensitive (TBZ-s) or TBZ-resistant (TBZ-r) isolate of P. digitatum. The residue levels of TBZ in fruit, evaluated as total residues, were not affected by the co-application of SBC in most samples. While TBZ residues in the fruit surface were not significantly affected by the dip temperature or by co-application of SBC, the rates of diffusion and penetration of TBZ into cuticular wax markedly increased in the presence of SBC or when TBZ was applied in combination with heat. TBZ residues in the inner tissue of fruits treated at 20 degrees C were not dependent upon the dip time or by the presence of SBC and were similar to those found in fruit treated with TBZ at 50 degrees C for 1 min, whereas significantly higher values were recorded in samples treated with TBZ at 50 degrees C for 3 min. When TBZ at 600 mg/L and 20 degrees C was applied in the presence of SBC at concentrations of 1-2 or 0.5-2%, it effectively reduced decay caused by the TBZ-resistant isolate of green mold in 'Nova' mandarins and 'Valencia' oranges. This treatment was also significantly more effective than TBZ alone to control green mold caused by a TBZ-s isolate in 'Valencia' oranges. The combination with SBC and mild heat (40 degrees C) and TBZ at 400 mg/L generally improved the control of a TBZ-r isolate of green mold with respect to the combined treatment at 20 degrees C. TBZ efficacy was also improved when applied at reduced rates (200 mg/L) and 50 degrees C, significantly suppressing green mold caused by a TBZ-s isolate of P. digitatum and effectively controlling a TBZ-r isolate. The rate of weight loss of 'Valencia' oranges was significantly increased by SBC treatment and was positively dependent upon the concentration of SBC used in the treatment, while the temperature of the treatment solution had little influence on later weight loss.     

Thiabendazole uptake and storage performance of cactus pear [Opuntia ficus-indica (L.) Mill. Cv Gialla] fruit following postharvest treatments with reduced doses of fungicide at 52 degrees C

The storage response of cactus pears [Opuntia ficus-indica Miller (L.) cv. Gialla] was investigated over 6 weeks at 6 degrees C, plus an additional week of simulated marketing period (SMP) at 20 degrees C, after a 3-min dip treatment with thiabendazole (TBZ) at 1000 mg/L at 20 degrees C or 150 mg/L TBZ at 52 degrees C. Untreated fruits were used as control. Following TBZ treatments at 20 and 52 degrees C, total residues were recovered from the peel of cactus pear, as the concentration of residues in the pulp was negligible. Treatments with 1000 mg/L TBZ at 20 degrees C resulted in a 2.82 mg/kg residue uptake (active ingredient, whole-fruit basis), whereas treatment at 150 mg/L TBZ left 1.09 mg/kg. TBZ showed great persistence over both storage and SMP: on average, in the fruits treated at 20 and 52 degrees C, over 72 and 68%, respectively, of TBZ was still present after SMP. Postharvest treatments with 1000 mg/L TBZ at room temperature did not affect the expression of slight-to-moderate chilling injury (CI), but reduced severe CI by approximately 50% and decay development by 63.4% in comparison to those of untreated fruit after SMP. The effectiveness of TBZ was much higher with the treatment at 150 mg/L TBZ at 52 degrees C, providing 91% control of severe CI and approximately 89% suppression of decay; no treatment damage occurred during storage and SMP. External appearance was better in fruit treated with 150 mg/L TBZ at 52 degrees C. Respiration rate, titratable acidity, soluble solids concentration, and acetaldehyde in the flesh were not significantly influenced by treatments. Ethylene production rate and ethanol levels in the flesh were significantly higher in the TBZ-treated fruit as opposed to those in the untreated control fruit.     

Residue levels and storage responses of nectarines, apricots, and peaches after dip treatments with fludioxonil fungicide mixtures

Mature apricots (Prunus armeniaca), nectarines [Prunus persica var. nectarine (Ait.)], and peaches [P. persica (L.) Batsch.] were subjected to a 2 min dip treatment with warm water at 48 degrees C or with fludioxonil (FLU) at 100 mg L-1 and 20 degrees C or at 25 mg L-1 FLU and 48 degrees C and then stored at 5 degrees C and 90-95% relative humidity (RH) for 1 week plus 1 additional week at 18 degrees C and approximately 80% RH. Fruit residue uptake was determined as a function of fungicide concentration, dip temperature, treatment time (only on nectarines), and fruit storage conditions. FLU residue level was closely related to fungicide concentration and treatment temperatures and was dependent on fruit species. FLU residues showed great persistence over both storage and shelf life. Fruit dipping in water at 48 degrees C effectively reduced decay development in cvs. 'May Grand' nectarines and 'Pelese' apricots but was ineffective in cvs. 'Red Top' and 'Sun Crest' nectarines during 7 days of storage compared with nontreated fruit. Decay rates in cvs. 'Glo Haven' peaches and 'Fracasso' apricots were very low in fruit dipped in water at both 20 and 48 degrees C. Fungicide treatments at 20 and 48 degrees C resulted in the total or almost total suppression of decay in all cultivars. During shelf life, fruit became very prone to decay, averaging 25.7-100% depending on the cultivar. Fruit dipping in hot water effectively reduced decay in 'Pelese' and 'Fracasso' apricots, 'Sun Crest' peaches, and 'May Grand' nectarines as compared to control, but was ineffective in 'Glo Haven' and 'Red Top' peaches. Fungicide treatments at 20 degrees C were more effective than hot water in most cultivars. The combination of FLU with water at 48 degrees C further improved the fungicide performance. Indeed, reduced levels (a fourth) of active ingredient were required to achieve a control of decay comparable to that for treatment at 20 degrees C. Residue levels in fruit after treatment with 100 mg L-1 FLU at 20 degrees C or with 25 mg L-1 FLU at 48 degrees C averaged approximately 0.6-2 mg kg-1, which were notably lower than the maximum residue limit (5 mg kg-1) allowed in the United States for stone fruit.     

Study of carbendazin residue accumulation on greenhouse and field-grown strawberries, after successive treatments with benomyl

Benomyl, a systemic fungicide used in preharvest treatments to prevent Botrytis and other fungal diseases, metabolizes to carbendazim (MBC). A study was undertaken to determine if the total residues of MBC of greenhouse and field-grown Douglas strawberries accumulate in fruits after successive fortnightly treatments with a commercial preparation of benomyl. Statistical analysis of the data obtained indicates that residues of MBC do not accumulate in fruits; on the contrary, they decrease over time.     

Comparison of ozone and UV-C treatments on the postharvest stilbenoid monomer, dimer, and trimer induction in var. 'Superior' white table grapes

Postharvest treatment of seedless white table grapes (var. 'Superior') with different gas ozone concentrations (3.88 and 1.67 g/h) for 1, 3, and 5 h induced an increase in stilbenoid biosynthesis [trans-resveratrol, piceatannol, and viniferinas (resveratrol dehydrodimers and dehydrotrimers)] during storage at 22 degrees C and 95% relative humidity. The maximal resveratrol concentration was reached after 2 days of storage, and this amount was similar to that induced by optimized UV-C treatments (1 min, 510 W, 40 cm). Although similar resveratrol concentrations accumulated in grapes after both UV-C and O3 treatments (maximum ozone production and time), the ozone treatment was more efficient in inducing viniferins accumulation in grape berries. A sequence in the biosynthesis of stilbenoids was observed, starting with the resveratrol monomer, continuing with the resveratrol dehydrodimers epsilon-viniferin and delta-viniferin, and ending with four different resveratrol dehydrotrimers. These trimers were different from alpha-viniferin, a trimer previously reported to be induced in grapes after biotic and abiotic stresses. Two alpha-viniferin isomers were also detected in the ozone-treated grapes, although at very low concentrations that prevented their quantification.     

Dehydrin from citrus, which confers in vitro dehydration and freezing protection activity, is constitutive and highly expressed in the flavedo of fruit but responsive to cold and water stress in leaves

A cDNA encoding a dehydrin was isolated from the flavedo of the chilling-sensitive Fortune mandarin fruit (Citrus clementina Hort. Ex Tanaka x Citrus reticulata Blanco) and designed as Crcor15. The predicted CrCOR15 protein is a K2S member of a closely related dehydrin family from Citrus, since it contains two tandem repeats of the unusual Citrus K-segment and one S-segment (serine cluster) at an unusual C-terminal position. Crcor15 mRNA is consistently and highly expressed in the flavedo during fruit development and maturation. The relative abundance of Crcor15 mRNA in the flavedo was estimated to be higher than 1% of total RNA. The high mRNA level remained unchanged during fruit storage at chilling (2 degrees C) and nonchilling (12 degrees C) temperatures, and it was depressed by a conditioning treatment (3 days at 37 degrees C) that induced chilling tolerance. Therefore, the expression of Crcor15 appears not to be related to the acquisition of chilling tolerance in mandarin fruits. However, Crcor15, which was barely detected in unstressed mandarin leaves, was rapidly induced in response to both low temperature and water stress. COR15 protein was expressed in Escherichia coli, and the purified protein conferred in vitro protection against freezing and dehydration inactivation. The potential role of Citrus COR15 is discussed.     

幼果期调亏对不同覆膜柑橘产量品质及水分利用效率的影响

调亏灌溉具有节水保肥、提质增效等特点,该研究尝试在调亏灌溉基础上引入地表覆膜技术,利用覆膜的保水控水作用,解决水分亏缺带来的土壤水分不足及后期减产问题。以鄂西地区树龄10 a的柑橘树（红肉脐橙,枳砧）为研究对象,探究覆膜条件下水分亏缺对柑橘品质、产量及水分利用效率（water use efficiency, WUE）的影响。试验于2019－2021年在幼果期设置轻度（L：80%～90%田间持水量）、中度（M：70%～80%田间持水量）、重度（S：60%～70%田间持水量）3个程度水分亏缺水平,另设置A（日本透湿性膜）、B（杜邦特卫强膜）、C（中国银黑双色膜）和不覆膜4个覆盖水平,以不覆膜充分灌溉为对照进行试验。结果表明：水分亏缺和覆膜均可显著改善柑橘果实品质（P<0.05）,其中M-A和M-B处理是提高柑橘品质的最优处理。水分亏缺和覆膜对产量及WUE的影响也达到显著水平,两者均能有效提高WUE,L和M处理均显著增加了柑橘产量,而S处理显著减小了柑橘产量,且两者的交互作用对产量及WUE影响也显著,其中M-A和M-B处理的产量和WUE均达到最高水平,2019、2020、2021年M-A和M-B处理的产量分别为44 793.6、45 325.1、43 126.8 kg/hm2和44 870.5、44 727.7、41 783.5 kg/hm2,WUE分别为7.31、7.68、7.08 kg/m3和7.47、7.47、6.89 kg/m3。因此,最优处理为柑橘品质、产量和WUE均达到较高水平的M-A和M-B。该研究可为鄂西地区柑橘产业的灌溉管理和提质增效提供理论依据。     

氮磷钾肥对红壤地区幼龄柑橘生长发育和果实产量及品质的影响

利用盆栽试验研究了氮、磷、钾肥对幼龄柑橘树生长发育和果实产量及品质的影响。结果表明,施用氮、磷、钾肥明显影响柑橘树新生叶片数和叶片大小;对柑橘三梢抽梢和生长状况也产生明显影响,不施氮、磷、钾肥处理的柑橘树三梢生长量分别为OPT处理(施足各种养分)的14.5%、74.5%和91.6%。不施氮、磷、钾肥处理的柑橘树开花数分别为OPT处理的28.9%、89.8%和91.9%;成果率分别为24.3%、83.3%和93.0%。不施氮、磷、钾肥柑橘果实产量分别下降22.2%、16.8%和21.2%;柑橘果实的品质指标尤其是外观品质受到严重影响。试验结果还表明,氮肥对红壤上种植的幼龄柑橘树的营养生长的影响程度大于磷肥,钾肥对营养生长影响程度最小,然而对柑橘产量和品质,氮、钾肥的影响程度大于磷肥。3年的试验结果说明,合理施用氮、磷、钾肥能明显促进幼龄柑橘树体生长发育,同时能提高柑橘产量和改善果实品质。     

Impact of postharvest disease control methods and cold storage on volatiles, color development and fruit quality in ripe 'kensington pride' mangoes

Postharvest diseases of mango fruit (Mangifera indica L.) cause economic losses during storage and can be controlled by chemical, physical, or biological methods. This study investigated the effects of different physical and/or chemical disease control methods on production of volatiles, color development and other quality parameters in ripe 'Kensington Pride' mango fruit. Hard mature green mango fruit were harvested from an orchard located at Carnavon, Western Australia. The fruit were heat-conditioned (8 h at 40 +/- 0.5 degrees C and 83.5 +/- 0.5% RH), dipped in hot water (52 degrees C/10 min), dipped in prochloraz (Sportak 0.55 mL x L(-1)/5 min), dipped in hot prochloraz (Sportak 0.55 mL x L(-1) at 52 degrees C/5 min), dipped in carbendazim (Spin Flo 2 mL x L(-1)/5 min), and dipped in hot carbendazim (Spin Flo 2 mL x L(-1) at 52 degrees C/5 min). Nontreated fruit served as control. Following the treatments, the fruit were air-dried and kept in cold storage (13 +/- 0.5 degrees C) for three weeks before being ripened at 21 +/- 1 degrees C. The ripe pulp of the fruit that was treated with hot prochloraz or carbendazim at ambient and high temperatures showed enhanced concentrations of volatiles, while heat conditioning and hot water dipping did not significantly affect the volatile development. Ripening time, and color development were measured daily while disease incidence and severity, weight loss, firmness, and concentrations of soluble solids, titratable acidity, ascorbic acid, total carotenoids, and volatiles were determined at the eating soft ripe stage. Hot water dipping or fungicide treatments (at ambient or at a high temperature) reduced postharvest diseases incidence and severity. Fruit quality (soluble solids concentration, titratable acidity, ascorbic acid and total caretonoids) was not substantially affected by any of the treatments.     

生草栽培对柑橘园土壤水分与有效养分及果实产量、品质的影响

试验研究生草栽培对柑橘园土壤水分和有效养分含量及果实产量品质的影响结果表明,生草栽培7～11月份干旱时期可提高果园土壤含水率;生草栽培初期降低果园土壤有效氮、磷、钙、镁、锰、铜和锌等矿质养分含量,但生草栽培2年后土壤有效氮、钾、铁和锌等矿质养分含量高于清耕对照。生草栽培可提高果实产量和果实可溶性固形物含量,降低果实柠檬酸含量,且种植百喜草比白三叶效果更明显     

Update on uses and properties of citrus flavonoids: new findings in anticancer, cardiovascular, and anti-inflammatory activity

Significantly, much of the activity of Citrus flavonoids appears to impact blood and microvascular endothelial cells, and it is not surprising that the two main areas of research on the biological actions of Citrus flavonoids have been inflammation and cancer. Epidemiological and animal studies point to a possible protective effect of flavonoids against cardiovascular diseases and some types of cancer. Although flavonoids have been studied for about 50 years, the cellular mechanisms involved in their biological action are still not completely known. Many of the pharmacological properties of Citrus flavonoids can be linked to the abilities of these compounds to inhibit enzymes involved in cell activation. Attempts to control cancer involve a variety of means, including the use of suppressing, blocking, and transforming agents. Suppressing agents prevent the formation of new cancers from procarcinogens, and blocking agents prevent carcinogenic compounds from reaching critical initiation sites, while transformation agents act to facilitate the metabolism of carcinogenic components into less toxic materials or prevent their biological actions. Flavonoids can act as all three types of agent. Many epidemiological studies have shown that regular flavonoid intake is associated with a reduced risk of cardiovascular diseases. In coronary heart disease, the protective effects of flavonoids include mainly antithrombotic, anti-ischemic, anti-oxidant, and vasorelaxant. It is suggested that flavonoids decrease the risk of coronary heart disease by three major actions: improving coronary vasodilatation, decreasing the ability of platelets in the blood to clot, and preventing low-density lipoproteins (LDLs) from oxidizing. The anti-inflammatory properties of the Citrus flavonoids have also been studied. Several key studies have shown that the anti-inflammatory properties of Citrus flavonoids are due to its inhibition of the synthesis and biological activities of different pro-inflammatory mediators, mainly the arachidonic acid derivatives, prostaglandins E 2, F 2, and thromboxane A 2. The anti-oxidant and anti-inflammatory properties of Citrus flavonoids can play a key role in their activity against several degenerative diseases and particularly brain diseases. The most abundant Citrus flavonoids are flavanones, such as hesperidin, naringin, or neohesperidin. However, generally, the flavones, such as diosmin, apigenin, or luteolin, exhibit higher biological activity, even though they occur in much lower concentrations. Diosmin and rutin have a demonstrated activity as a venotonic agent and are present in several pharmaceutical products. Apigenin and their glucosides have been shown a good anti-inflammatory activity without the side effects of other anti-inflammatory products. In this paper, we discuss the relation between each structural factor of Citrus flavonoids and the anticancer, anti-inflammatory, and cardiovascular protection activity of Citrus flavonoids and their role in degenerative diseases.