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Eugenol is an important phenylpropanoid in strawberry and the accumulation is affected by various abiotic stresses. In this study, the expression patterns of two transcription factors (TFs) (FaMYB10 and FaEOBII) and two synthetic genes (FaEGS1 and FaEGS2) involved in eugenol synthesis were characterized in Fragaria × ananassa cv. ‘Xiaobai’. Sequence analysis showed the four genes contained several cis-acting elements that were related to phytohormones and environmental stress signal responsiveness. FaEGS1 and FaEGS2 were clustered in the same group clade. The four genes were expressed in all analysed tissues and, in particular, expressed to higher relative expression levels in leaves. The expression of FaEGS1, FaEGS2, and FaEOBII was the highest in large green fruits, and FaMYB10 had the highest expression in red-ripening fruits. The amount of eugenol showed a stage-specific profile. The expression of these four genes was up-regulated by ethephon (ETH), dark, drought, heat, and salt treatments accompanied by the increase of eugenol production. Concentration and timing of cadmium treatment affected gene expression. Cadmium inhibited the expression of FaEGS1 and FaEOBII, but significantly promoted the expression of FaEGS2 and FaMYB10 and eugenol content. The results provide a basis for elucidating the role of these genes in response to abiotic stresses, and regulating the accumulation of eugenol, an important constituent of volatile compounds in many economically important and aromatic plants.

The biosynthetic pathway of volatile phenylpropanoids, including 4-allyl-2-methoxyphenol (eugenol), has been investigated in petunia (Petunia hybrida). However, the regulatory network for eugenol accumulation in strawberry (Fragaria × ananassa Duch.) fruit remains unclear. Here, an R2R3-type MYB transcription factor (TF; FaMYB63) was isolated from strawberry by yeast one-hybrid (Y1H) screening using the promoter of the FaEGS1 (eugenol synthase 1 [EGS 1]) gene, which encodes the enzyme responsible for the last step in eugenol biosynthesis. FaMYB63 is phylogenetically distinct from other R2R3-MYB TFs, including FaEOBІІ (EMISSION OF BENZENOID II [EOBII]), which also participates in regulating eugenol biosynthesis in strawberry receptacles. Reverse transcription quantitative PCR (RT-qPCR) assays showed that the expression of FaMYB63 was tissue-specific and consistent with eugenol content through strawberry fruit development, was repressed by abscisic acid, and was activated by auxins (indole-3-acetic acid). Overexpression and RNA interference-mediated silencing of FaMYB63 resulted in marked changes in the transcript levels of the biosynthetic genes FaEGS1, FaEGS2, and FaCAD1 (cinnamyl alcohol dehydrogenase 1 [CAD1]) and, thereby, the accumulation of eugenol. Electrophoretic mobility shift, Y1H, GUS activity, and dual-luciferase activity assays demonstrated that the transcript levels of FaEOBІІ and FaMYB10 were regulated by FaMYB63, but not the other way around. Together, these results demonstrate that FaMYB63 directly activates FaEGS1, FaEGS2, FaCAD1, FaEOBІІ, and FaMYB10 to induce eugenol biosynthesis during strawberry fruit development. These findings deepen the understanding of the regulatory network that influences eugenol metabolism in an edible fruit crop.

The citrate content of strawberry fruits affects their organoleptic quality. However, little is known about the transcriptional regulatory mechanisms of citric acid metabolism in strawberry fruits. In this study, the R2R3-MYB transcription factor FaMYB5 was identified and placed in the R2R3-MYB subfamily. FaMYB5 is found in the nucleus and shows tissue- and stage-specific expression levels. Citric acid content was positively correlated with FaMYB5 transcript levels. Upregulated FaMYB5 increased citric acid accumulation in transient FaMYB5-overexpressing strawberry fruits, whereas transient RNA silencing of FaMYB5 in strawberry fruits resulted in a reduction of citric acid content. The role of FaMYB5 was verified using stable transgenic NC89 tobacco. Furthermore, a yeast one-hybrid assay revealed that FaMYB5 influences citric acid accumulation by binding to the FaACO (aconitase), FaGAD (glutamate decarboxylase), and FaCS2 (citrate synthase) promoters. Dual-luciferase assays were used to demonstrate that FaMYB5 could activate FaCS2 expression and repress the transcription levels of FaACO and FaGAD. This study identified important roles of FaMYB5 in the regulation of citric acid metabolism and provided a potential target for improving strawberry fruit taste in horticultural crops.

Salinity is one of the major environmental stresses that limit crop growth and productivity. In this study, the FvMYB24 gene that encodes an R2R3-type MYB transcription factor was cloned and characterized. An expression analysis showed that FvMYB24 had a tissue- and stage-specific profile and was induced by salt treatment. Arabidopsis plants that overexpressed transgenic FvMYB24 exhibited a higher germination rate, fresh weight, chlorophyll content, and longer root length than the wild type (WT) under salt stress. The transgenic plants had higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) and the accumulation of proline, while these plants accumulated lower amounts of malondialdehyde (MDA) compared with the WT. Furthermore, our results also revealed that the overexpression of FvMYB24 up-regulated the expression of several stress-related genes (AtSOS1, AtSOS2, AtSOS3, AtSOD, AtPOD, AtCAT1, AtNHX1, and AtLEA3) in response to salt stress, thus, enhancing the tolerance of transgenic Arabidopsis. An analysis of the cis-acting elements in the SOS1, SOS2, and SOS3 promoters revealed MYB-binding sites. However, FvMYB24 could only bind to the SOS1 promoter to mediate salt tolerance but not to the SOS2 and SOS3 promoters. These findings suggest that FvMYB24 could potentially be used as a positive regulator in transgenic plant breeding to improve the tolerance of strawberry plants to salt.

Strawberries (Fragaria × ananassa Duch.) are considered a functional food and pleasing fruit in China, mainly because of their high concentration of ellagic acid (EA) and their aroma. A total of 127 volatile compounds were identified by HS–SPME–GC–MS. Changes in volatile constituents and EA were investigated in 50 strawberry cultivars in the red-ripening stage and in 6 cultivars, including ‘Benihoppe’, ‘Snow White’, ‘Yanli’, ‘Kaorino’, ‘Tokun’, and ‘Xiaobai’, at four developmental stages. The results indicated that the components and amounts of volatile compounds and EA markedly varied among and within cultivars. Through multivariate statistical analysis of the volatile compounds, 50 cultivars were divided into 4 clusters. Aromatic components that affected the cluster formation of cultivars were detected. Volatile compounds varied quantitatively among the 6 varieties during the developmental stages, and distinct changes were observed in both red-turning fruits and red-ripening fruits compared with white fruits. Except for ‘Xiaobai’, which showed the highest EA content at the red-ripening stage, the other 5 cultivars exhibited the highest EA level at the large green fruit stage. Partial least squares–discriminant analysis (PLS–DA) of the profiles of volatile compounds indicated that large green fruits were characterized by EA and aldehydes; white fruits were characterized by ketones and alkanes; and red-ripening fruits were characterized by esters, acids, furans, and alcohols. The results contribute new and important information to breeding programs and the desirable cultivation of strawberry production.

‘Bartlett’ is one of the consumer’s favorite pears due to its juicy, delicate texture, and excellent flavor; however, the short storage life of the fruit limits its market value. One main factor affecting fruit quality is the early peel yellowing. In this study, the effects of the delayed precooling and 1-MCP treatment on the fruit quality were investigated. For the delayed precooling treatment, the fruit were held at 20 °C for 0, 12, and 24 h before they were moved to a cold storage (−1 °C). For the 1-MCP treatment, the fruit were exposed to 1-MCP at 0.3 μL/L for 24 h in the cold storage. After 1-MCP treatment, all fruits were stored at −1 °C and evaluated over a 6-month period. Results showed that delayed precooling of the field harvested fruit significantly extended the fruit cooling rate. Treatment with 1-MCP significantly inhibited the fruit respiration and ethylene production, delayed fruit ripening capacity, retarded chlorophyll degradation and eliminated senescence scald; however, these effects were not observed in the non-1-MCP treated fruit. Expression of the ethylene synthesis genes (PcACS1, PcACS4, PcACS5, and PcACO1) and receptor genes (PcETR1, PcETR2, and PcERS) was dramatically increased by delayed precooling time, but their expression was suppressed by 1-MCP treatment. Two genes (PcACS5 and PcETR1) were hierarchical among controls 0, 12 and 24. In contrast, the PcACS2 gene was upregulated by 1-MCP. The transcription level of the chlorophyll degradation genes PcPPH, PcSGR1, PcRCCR, and PcNYC was increasing in the non-1-MCP treated fruit, but inhibited by 1-MCP treatment during the cold storage time and the inhibition level was negatively related to the delayed precooling time. The expression of PcPAO and PcCHL1 dramatically decreased in the non-1-MCP treatments and little effect of 1-MCP treatment on their expression was observed. In conclusion, 0 h of delayed precooling time or 1-MCP treatment prevented peel yellowing and extended storage life of ‘Bartlett’; howerver, 1-MCP treatment delayed fruit ripening and the fruit required 14 days at 20 °C to ripen following 4–6 months of storage.

The apple (Malus domestica) MdMYB1 gene encodes an R2R3-MYB transcription factor (TF) that regulates anthocyanin biosynthesis. The transient and stable expression of the apple basic helix-loop-helix 3 gene, MdbHLH3, produces anthocyanin pigmentation in apple fruit and calli. In order to understand the MdMYB1- and MdbHLH3-related regulatory mechanisms of anthocyanin biosynthesis, we established and characterized the expression of those two genes in stably transformed tobacco (Nicotiana tabacum NC89) plants, including the phenotypic differences in anthocyanin-containing flowers, ovaries, anthers and anthocyanin-free leaves. A real-time PCR analysis showed that the expression levels of the MdMYB1 and MdbHLH3 transgenes were up-regulated in all tobacco organs. However, the bHLH and MYB TFs, NtAN1 and NtAN2, were not detected in tobacco leaves, respectively, indicating that neither can individually activate anthocyanin biosynthesis. However, MdMYB1 induced pigment accumulation in ovaries because NtAN1 is active in that organ. Thus, the endogenous bHLH TF is necessary for anthocyanin biosynthesis in tobacco. Furthermore, MdMYB1 binding to the promoters of the anthocyanin biosynthesis genes MdDFR and MdUFGT activated their expression in apple. However, because NtAN2 is not activated in leaves or ovaries, the pigmentation patterns were not significantly altered in these organs in MdbHLH3-overexpressing tobacco. Thus, the data indicated that MdMYB1 regulated anthocyanin biosynthesis directly by binding the MdDFR and MdUFGT promoters, and interacted with the tobacco bHLH TF, triggering anthocyanin accumulation.

Bosc is a winter cultivar of european pear (Pyrus communis) that has a relatively short storage life partially due to a high ethylene production rate (EPR) during cold storage. ‘Bosc’ pears were harvested at commercial maturity and treated with gas 1-methylcyclopropene (1-MCP) at 0, 0.15, and 0.3 µL·L−1 and stored at −1.1 °C for 8 months. Results indicated that all 1-MCP treatments inhibited EPR and respiration rate (RR), retarded the degradation of chlorophyll and titratable acidity (TA), and extended storage quality; but inhibited ripening capacity. 1-MCP at 0.15 and 0.3 µL·L−1 had the same efficacy on keeping fruit quality although its higher rate was more efficient on inhibiting EPR and RR. The expression of ethylene synthesis genes (PcACS1, PcACS2, PcACS4, PcACS5, and PcACO1) and receptor genes (PcETR1, PcETR2, and PcERS1) was upregulated in control fruit during storage and they were downregulated significantly by 1-MCP treatments. In contrast, the ethylene receptor genes of PcETR5 and PcCTR1 were downregulated in control fruit during storage and were unaffected by 1-MCP treatments. Although the transcription levels of chlorophyll degradation genes PcPPH, PcNOL, PcSGR, PcRCCR, PcNYC, and PcPAO were all upregulated in control fruit during storage and downregulated by 1-MCP; only PcCHL was downregulated in the control and 1-MCP had no consistent effect on it. The relationship of ethylene biosynthesis/perception with chlorophyll degradation and storage quality in european pears was discussed.

‘Bartlett’ pear fruit has a relatively short storage life due to increased ethylene production induced by cold storage. The effects of preharvest aminoethoxyvinylglycine (AVG) (an ethylene biosynthesis inhibitor) spray rate and timing on storability of ‘Bartlett’ pear fruit at three harvest maturities [H1: control fruit firmness (CFF) ≈ 84.5 N; H2: 12 d after H1 when CFF ≈ 76.0 N; and H3: 17 d after H1 when CFF ≈ 73.4 N] were measured with respect to ethylene production, storage quality and ripening capacity during 5 months of storage at −1.1 °C. Compared to non-treated control, AVG at 60 mg L −1 applied 1 week before H1 (WBH1) suppressed ethylene production, respiration rate, reductions in fruit firmness and green color, and reduced senescence disorders (e.g., by 81.5% and 54.0%) while maintaining ripening capacity for H1 and H2 fruit. Compared to 60 mg L −1 , AVG at 120 mg L −1 applied 1WBH1 had similar effects on storage quality but delayed ripening capacity by one month. AVG at 30 mg L −1 applied 1 WBH1 and 120 mg L −1 applied 2 WBH1 had little effect on any of the storage responses measured. AVG treatment did not affect ethylene production or storage quality of H3 fruit. AVG at 60–120 mg L −1 applied 1 WBH1 and 120 mg L −1 applied 2 WBH1 did not affect the initial harvest maturity (H1), but delayed fruit maturation on the tree by 5–7 d. These results suggest that preharvest AVG treatment efficacy on extending harvest window and reducing storage losses of ‘Bartlett’ pear is influenced by application rate, timing and fruit harvest maturity.

1-Methylcyclopropene (1-MCP) is valuable technology for control superficial scald (SS) and to extend storage life of European pears, but initiating ripening capacity (RC) of the 1-MCP treated fruit following cold storage is a challenge. Green ‘Anjou’ and its bud mutation red ‘Anjou’ pears at commercial maturity were treated with 1-MCP at 0.15 μL L−1 and stored at −1 °C for 7 months. While control fruit of both cultivars developed RC and SS, 1-MCP treated green and red pears developed neither RC nor SS in 7 d at 20 °C following 2–7 months of storage. RC development was triggered by post-storage ethylene conditioning (PSEC) in 1-MCP treated red but not green pears following 6–7 months of storage. Ethylene production increased in control fruit and was inhibited by 1-MCP in both green and red pears during storage, however, the 1-MCP treated red but not green pears increased ethylene production after 5 months of storage. PSEC enhanced the ethylene production in 1-MCP treated red but not green pears following 6–7 months of storage. In correspondence, the expression of ethylene synthesis genes (PcACO1, PcACS1, PcACS2, PcACS4, and PcACS5) increased after 6 month of storage in 1-MCP treated red but not green pears. The signal genes (PcETR1, PcETR2, PcETR5 and PcCTR1) were stable at extremely low level in 1-MCP treated green and red pears during cold storage. PSEC up-regulated PcACO1 and PcETR2 after 6 months of storage, and down-regulated the other genes in 1-MCP treated red pears, while it down-regulated all the genes in 1-MCP treated green pears. In conclusion, PcACO1 may play an important role in initiating ripening capacity in 1-MCP treated red ‘Anjou’ pear upon PSEC.

Loss of green skin color and the onset of senescent scald (scald) in ‘Comice’ pears affect fruit quality and reduce the market value. To understand the molecular mechanisms of chlorophyll degradation in the skins of ‘Comice’ pears, fruit were exposed to 1-methylcyclopropene (1-MCP) at 0.15 and 0.3 μL L−1 and stored at -1.1 °C for up to six months. The results showed ethylene production rate, and respiration rate were significantly inhibited in pears treated with 1-MCP at 0.15 and 0.3 μL L−1. Senescent scald was eliminated, and the amount of extractable juice (EJ) remained constant, and chlorophyll degradation was retarded. However, the ripening capacity was inhibited. Ripening capacity recovered (by 14 days following warming to room temperature) in pears treated with 1-MCP at the lower concentration (0.15 μ L L−1) but the fruit treated with 1-MCP at the higher concentration (0.3 μL L−1) failed to ripen. The expressions of the ethylene synthesis genes (PcACS1, PcACS4, PcACS5, and PcACO1) and receptor genes (PcETR1, PcETR2, PcETR5, and PcERS1) were upregulated during storage in the control fruit but were significantly repressed by the 1-MCP treatments. In contrast, the expression of PcACS2 was upregulated by the 1-MCP treatments. The expressions of the chlorophyll degradation genes (PcPPH, PcNOL, PcSGR1, and PcPAO) were significantly higher in the control fruit but suppressed in the 1-MCP-treated fruit. The transcription levels of PcRCCR and PcCLH1 decreased during the six months of cold storage period and 1-MCP had little effect on their expressions. The correlations between chlorophyll degradation and the ethylene synthesis genes and signal-related genes indicated that 1-MCP delayed chlorophyll degradation by inhibiting the ethylene production rate and suppressing the expressions of the PcPPH, PcNOL, PcSGR1, and PcPAO genes, which were closely associated with the chlorophyll catabolic pathway in ‘Comice’ pears.

‘Starkrimson’ is a highly profitable red-skinned european pear (Pyrus communis) cultivar that has a short storage life due mainly to the development of a mealy texture upon ripening and an internal browning (IB) disorder during or after storage. In 2013, ‘Starkrimson’ pears were sprayed with aminoethoxyvinylglycine (AVG) at 0, 30, 60, and 120 mg·L−1 1 week before harvest or treated with 1-methylcyclopropene (1-MCP) at 0.3 µL·L−1 for 24 hours shortly after harvest, then stored at −1.1 °C and evaluated over a 16-week period. The experiment was repeated in 2014. After 2 weeks of storage, control fruit (nontreated) had a higher respiration rate and ethylene biosynthesis than AVG or 1-MCP-treated fruit. Following 12 weeks of storage, control fruit exhibited a greater incidence of mealy texture and greater extractable juice (EJ) after ripening, and by 16 weeks significantly higher IB relative to AVG and 1-MCP-treated fruit. AVG at 30 mg·L−1 had little effect on any of the storage responses measured compared with control. AVG at 60 mg·L−1 reduced ethylene synthesis, respiration rate, and titratable acidity (TA) loss and maintained high eating quality with low EJ. Fruit treated with 60 mg·L−1 AVG also developed markedly less IB following 16 weeks of storage than control or 30 mg·L−1 AVG treatments. AVG at 120 mg·L−1 did not improve storage quality achieved with 60 mg·L−1 but delayed ripening capacity by 1 month. 1-MCP markedly inhibited ethylene synthesis and respiration rate and eliminated IB during 16 weeks of storage; however, 1-MCP-treated fruit required 14 days at 20 °C to ripen to high eating quality following 12 to 16 weeks of storage compared with 5 days for 60 mg−L−1 AVG. Both AVG and 1-MCP suppressed the expressions of ethylene synthesis (PcACS1, PcACS4, PcACS5, and PcACO1) and perception genes (PcETR1, PcETR2, and PcETR5) although 1-MCP was more efficient than AVG. In conclusion, preharvest AVG applications at 60 mg·L−1 or postharvest 1-MCP treatment at 0.3 µL·L−1 extended storage life of ‘Starkrimson’; however, 1-MCP inhibited ripening capacity whereas 60 mg·L−1 AVG did not.

A continuing challenge for commercializing 1-methylcyclopropene (1-MCP) to control superficial scald (SS) and extend storage life of ‘d’Anjou’ pear (Pyrus communis L.) is how to initiate ripening capacity (RC) in 1-MCP treated fruit following cold storage. ‘D’Anjou’ pears harvested at 3 maturities (H1 ≈ 66.7 N, H2 ≈ 58.0 N, and H3 ≈ 55.6 N) were treated with 1-MCP at 0.15 µl L-1 and stored either at the commercial storage temperature -1.1°C (1-MCP at -1.1°C), or at 1.1°C (1-MCP at 1.1°C) or 2.2°C (1-MCP at 2.2°C) for 8 months in 2011 and 2012. Control fruit stored at -1.1°C developed RC and significant SS within 7 d at 20°C following 2-5 and 3-5 months in 2011 and 2012, respectively. While 1-MCP at -1.1°C fruit developed neither RC nor SS for 8 months, 1-MCP at 1.1°C fruit developed RC with relatively low levels of SS within 7 d at 20°C following 5-8 and 6-8 months in 2011 and 2012, respectively. 1-MCP at 2.2°C fruit lost quality (yellowing and decay) quickly during storage. Post-storage ethylene conditioning could not ripen 1-MCP at -1.1°C fruit until 7-8 and 8 months in 2011 and 2012, respectively, however, ripened 1-MCP at 1.1°C fruit following 4-6 months in both production years. H1 and H2 fruit were similar in responding to 1-MCP with respect to developing RC. 1-MCP treated H3 fruit developed RC following 7-8 months of storage at -1.1°C in 2011 but did not develop RC for 8 months in 2012. In conclusion, storage at 1.1°C can facilitate the initiation of RC in 1-MCP treated ‘d’Anjou’ pears with relatively low SS following 6-8 months of cold storage; PSEC can ripen the 1-MCP at 1.1°C fruit following 4-6 months of cold storage. Late harvest may not be a useful protocol for ripening 1-MCP treated ‘d’Anjou’ pears due to an inconsistent efficacy among production years.

A continuing challenge for commercializing 1-methylcyclopropene (1-MCP) to extend the storage life and control superficial scald of ‘d’Anjou’ pear ( Pyrus communis L.) is how to initiate ripening in 1-MCP treated fruit. ‘D’Anjou’ pears harvested at commercial and late maturity were treated with 1-MCP at 0.15 μL L −1 and stored either at the commercial storage temperature −1.1 °C (1-MCP@−1.1 °C), or at 1.1 °C (1-MCP@1.1 °C) or 2.2 °C (1-MCP@2.2 °C) for 8 months. Control fruit stored at −1.1 °C ripened and developed significant scald within 7 d at 20 °C following 3–5 months of storage. While 1-MCP@−1.1 °C fruit did not develop ripening capacity due to extremely low internal ethylene concentration (IEC) and ethylene production rate for 8 months, 1-MCP@1.1 °C fruit produced significant amounts of IEC during storage and developed ripening capacity with relatively low levels of scald within 7 d at 20 °C following 6–8 months of storage. 1-MCP@2.2 °C fruit lost quality quickly during storage. Compared to the control, the expression of ethylene synthesis ( PcACS1 , PcACO1 ) and signal ( PcETR1 , PcETR2 ) genes was stable at extremely low levels in 1-MCP@−1.1 °C fruit. In contrast, they increased expression after 4 or 5 months of storage in 1-MCP@1.1 °C fruit. Other genes ( PcCTR1 , PcACS2 , PcACS4 and PcACS5 ) remained at very low expression regardless of fruit capacity to ripen. A storage temperature of 1.1 °C can facilitate initiation of ripening capacity in 1-MCP treated ‘d’Anjou’ pears with relatively low scald incidence following 6–8 months storage through recovering the expression of certain ethylene synthesis and signal genes.

Influence of preharvest sunlight exposure on superficial scald development in 'd'Anjou' pears during cold storage was investigated. The biochemical changes related to scald including α-farnesene, conjugated trienols (CTols), antioxidants, antioxidant enzyme activities were monitored among separated blushed and shaded peels of unbagged fruit as well as the whole peel of bagged fruit. In unbagged fruit, scald symptom was restricted to shaded peel; while there was no difference in α-farnesene between blushed and shaded peels, CTols increased significantly in shaded peel along with scald development after 3months storage. Bagging treatment increased both α-farnesene and CTols significantly and enhanced scald. Preharvest sunlight exposure significantly increased certain antioxidant contents and antioxidant enzyme activities in blushed peel at harvest and during storage. These results reveal a direct role of CTols during development of scald, however, antioxidant systems may play an important role in α-farnesene oxidation to CTols and scald susceptibility in 'd'Anjou pears.

Soil pH is an important factor affecting the availability of soil nutrients that impact plant growth. Given the susceptibility of soil pH to excessive fertilization and the widespread use of manures, it is essential to examine the influence of soil pH on the distribution and availability of soil nutrients. We sampled and analyzed brown soils from pear orchards in thirteen towns in Wendeng county. Samples were obtained from areas along or between rows of trees at specified distances and depths. The results showed that the soil pH fluctuated from 4.06 to 6.59 in October 2008 and from 4.24 to 7.57 in April 2009. The quantity of soil samples with pH below 5.50 increased by 34.6%. Analysis of the soil pH for samples obtained along the rows of trees showed that the pH decreased as the depth increased (except for the range 5.5 to 6.0); soil pH in the samples obtained between the rows of trees demonstrated different trends. The average organic matter (O.M.) content as well as the N ( NH 4 + ) and available P, K, Cu, Zn, Fe, and Mn contents in the samples collected in October 2008 were higher than those observed in April 2009. Conversely, the values for other available nutrients were lower than those in the samples collected in April 2009. The available nutrients and organic matter (O.M.) content in different pH ranges varied. The soil pH was significantly or very significantly correlated with N ( NH 4 + and NO 3 - ), available K, Cu, Fe, and exchangeable Ca for the October 2008 samples, while a significant or very significant correlation existed between N ( NH 4 + ), available P, Zn, exchangeable Ca, and exchangeable Mg for the April 2009 samples. The correlations between soil pH and the amounts of available nutrients and organic matter (O.M.) along the rows of trees in September 2009 were nearly consistent with those between the rows.

The focus of the study described herein is the characterization of the high-pressure hydraulic electronic unit injector (HEUI) and of the electronic unit injector (EUI) diesel injection systems. The characterization items include injection pressure, injection rate, injector response time, needle lift, start up injection transient, and dynamic discharge coefficient of the nozzles. Macroscopic and microscopic spray visualizations were also performed. The effects of injection conditions and nozzle configurations on injection characteristics were reviewed. Nozzle sac pressure was measured to correlate with the up-stream injection pressure. A LabVIEW data acquisition and controls system was implemented to operate the injection systems and to acquire and analyze data. For an HEUI system, based on the results of the study, it can be concluded that common-rail pressure and length of the injection rate-shaping pipe determine the injection pressure, while the pressure rising rate and injection duration determine the peak injection pressure; it was also found that the nozzle flow area, common-rail pressure, and the length of the rate-shaping pipe are the dominating parameters that control the injection rate, and the rate shape is affected mainly by common-rail pressure, especially the pressure rising rate and length of the rate-shaping pipe. Both injection pressure and ambient pressure affected the spray tip penetration significantly. The penetration increased corresponding to the increase of injection pressure or decrease of ambient pressure. The variation of spray penetration depends on the type of injection system, nozzle configuration, and ambient pressure. The large penetration variation observed on the HEUI sprays could be caused by eccentricity of the VCO (valve-covered-orifices) nozzle. The variation of the mini-sac nozzle was 50% less than that of the VCO nozzle. The near-field spray behavior was shown to be highly transient and strongly depended on injector design, nozzle configuration, needle lift and oscillation, and injection pressure.

To improve storage/shipping quality of sweet cherry (Prunus avium L.), the effect of calcium chloride (CaCl2) added to hydro-cooling water on physiological and biochemical processes related to fruit and pedicel quality was investigated on two major cultivars. The fruit tissue Ca content increased up to 29-85% logarithmically for 'Sweetheart' and 39-188% linearly for 'Lapins' as CaCl2 rate increased from 0.2% to 2.0% at 0 °C for 5 min. The increase of fruit tissue Ca content was accompanied by reductions in respiration rate, ascorbic acid degradation, and membrane lipid peroxidation, which enhanced total phenolics content and total antioxidant capacity, and resulted in increases in fruit firmness and pitting resistance and decreases in titratable acidity loss and decay of both cultivars. Pedicel browning was inhibited by CaCl2 at 0.2% and 0.5%, but increased by higher rates at 1.0% and 2.0%, possibly via modifying membrane lipid peroxidation.

The dependencies of line intensity and linewidth of degenerate four wave mixing (DFWM) on the crossing angle have been investigated via OH A2Σ − X2Π transitions in a flame. The measured results were compared with the theoretical predictions and other experimental results. It was found that the saturation effect was important and must be considered. When using the DFWM method to measure the temperature, a suitable crossing angle should be chosen and the absorption correction should be taken into account.

The degenerate four-wave mixing (DFWM) spectra method was employed to measure the temperature in a premixed propane-oxygen flame via OH radicals. The focus was to study the dependencies of the signal-to-noise ratio and linewidth of DFWM on the crossing angle. It was found that temperature measurements via DFWM could be made with crossing angles up to 13 °. Also, the DFWM signals were detectable for a crossing angle up to 25 ° with acceptable signal-to-noise ratio. The results suggest that it is possible to use DFWM two-dimensional imaging as a realistic diagnostic technique.

Some research has studied the effects of ethanol blended diesel (E-diesel) on emissions due to the availability of ethanol. However, a co-solvent or emulsifier is needed to provide better mixing of these two fuels, which would complicate the production process. In recent years, researchers have reported that biodiesel is a good co-solvent in terms of its miscibility with ethanol. Therefore, the present study utilizes the name “E-Biodiesel” representing the blend of ethanol and biodiesel as an alternative fuel. In this paper, the effects of blending ratios (B100, B80E20, and B60E40) of ethanol-biodiesel on viscosity, spray vaporization, engine combustion, and exhaust emissions are investigated. The viscosity measurements show that appropriate ethanol-biodiesel blends could approach the viscosity of ultra-low sulfur diesel (ULSD). The effect of blends on fuel spray structure is investigated by using two single-hole injectors with different nozzle orifice diameters (80μm and 150 μm) and high-speed Schlieren imaging. The results indicate that different patterns of spray vaporization are observed due to the addition of ethanol at different ambient pressure. The combustion and emission tests are carried out in a multi-cylinder high-speed diesel engine, and the effects of E-Biodiesel are significant with respect to the power output, fuel consumption, and emissions. As a result, nitrogen oxides (NOX ) and particulate matter (PM) could be reduced simultaneously by the adjustment of injection timing and exhaust gas recirculation (EGR). Therefore, with proper blending ratios of biodiesel and ethanol, E-biodiesel could be considered viable as an alternative fuel in the future.Copyright © 2011 by ASME

By selecting a number of resonant A 21 rotational lines in the optical–optical double resonance multiphoton ionization spectroscopy (OODR‐MPI) of ammonia‐d3, we have obtained rotationally resolved spectra of the ND3 B←A 21←X 00 transitions in the range of 550–730 nm, in which not only were we able to reanalyze rotationally the previously studied bands [J. Opt. Soc. Am. B 7, 1884(1990)], but also to assign rotationally and vibronically some novel spectra pertaining to the ν1, ν3, ν4, and ν3+ν4 excitations. Based on the symmetry assignment and the relationship of the vibronic coupling level energies between the single and dual mode cases, we have found that the Jahn–Teller splitting of the ND3 B state invokes a novel type of the Fermi resonance, the nonadiabatic Fermi resonance. By taking account of this Fermi resonance, the modified vibronic coupling parameters of the ν3 and ν4 modes were calculated to be λ3=0.047 and λ4=0.023, which agrees well with the previous theoretical expectation that the ammon...

The fine structure of the b(1)3Πu state of the lithium dimer was observed for the first time and studied using Doppler‐free polarization spectroscopy. The triplet state was accessed by excitation of the A 1Σ+u(v=2,J=33)∼b(1)3Πu (v=9,N=32,F1,e) spin–orbit perturbed levels. The remaining two fine structure levels were excited by using the Zeeman interaction to mix levels of different J. Two polarization geometries, π pump and σ pump, were used to study separately different groups of MJ levels in magnetic fields up to 3 kG. An irreducible tensor derivation of the fine structure and Zeeman Hamiltonian matrix in Hund’s case (b) symmetrized basis functions was carried out and used to determine the perturbation parameters and the spin–spin and spin–rotation fine structure constants by a fit to the Zeeman splitting pattern. The spin–orbit contribution to the fine structure is too small in the high J states to be found accurately. The electronic spin–orbit coupling perturbation for the interaction between the sing...

Polarization spectroscopy offers certain advantages for sub-Doppler studies of Mj sublevels in Zeeman effect studies due to the Mj dependence of the line strength functions and the Zeeman selection rules. This is demonstrated in a comparison with sub-Doppler intermodulated fluorescence spectroscopy.

New U.S. Environmental Protection Agency regulations are forcing locomotive manufacturers and railroads to reduce pollutant emissions from locomotive operation. Locomotive engines will be required to meet the applicable standards at the time of original manufacture. A variety of emissions-reduction technologies can be used, such as alternative fuels, additives in lubricant oil, and aftertreatment technologies (e.g., selective catalytic reduction and particulate traps). Emissions reduction can also be accomplished inside the cylinder, using advanced diesel fuel injectors that have a significant impact on the quality of spray and charge preparation before engine combustion and subsequent events. High-speed optical measurements have been collected at elevated ambient pressures for sprays from a modular common rail injection system at Argonne National Laboratory in order to investigate spray structure and dynamics. High-speed laser imaging was used to explore the effects of various parameters on the spray structure. The experimental parameters included were ambient gas density, injection pressure, number of spray holes, injection strategy, and internal orifice size. Spray symmetry and structure were found to depend significantly on the nozzle geometry or manufacturing variances and the operating conditions.

Wall-wetting due to liquid fuel film motion and fuel droplet impingement on combustion chamber walls is a major source of unburned hydrocarbons (UBHC), and is a concern for oil dilution in PFI engines. An experimental study was carried out to investigate the effects of injection timing, a charge motion control device, and the matching of injector with port geometry, on the "footprints" of liquid fuel inside the combustion chamber during the PFI engine staffing process. Using a gasoline-soluble dye and filter paper deployed on the cylinder liner and piston top land surfaces to capture the liquid fuel footprints, the effects of the mixture formation processes on the wetted footprints can be qualitatively and quantitatively examined by comparing the wetted footprint locations and their color intensities. Real-time filming of the development of wetted footprints using a high-speed camera can also show the time history of the fuel wetting process inside an optically accessible engine. The results show that the cold-start in-cylinder wetted footprint is quite engine specific, depending on the intake-port to injector matching. The tumble mixture-motion plate inserted in the intake port creates more turbulence and enhances mixing during the intake process, and therefore significantly reduces the wetted fuel footprint. Limited UBHC measurements were also performed on the engine to compare with the imaging results.

The third order nonlinear optical properties of a trimer branched chromophore system and its linear molecule analog are investigated. Two-photon absorption and degenerate four wave mixing measurements were carried out on both systems. An enhancement in the nonlinear optical effect is observed for the branched trimer molecule in comparison to the linear chromophore system. Ultrafast time-resolved measurements were carried out to probe the excited state dynamics in the branched structures. The time-resolved measurements suggest that the two important processes affecting the nonlinear optical properties in the trimer system, charge transfer stabilization and initial electronic delocalization, occur on two different time scales.

This paper examines the action of various metal catalysts on red emitter formation. The chlorine content of chemically generated singlet oxygen was monitored by chemical analysis and chromatography. The presence of chlorine in chemically generated singlet oxygen indicates that chlorine plays some role in red emitter formation. The radiative life of the emitter was calculated from spatial chemiluminescence decay in the chemiluminescence cell. Results showed that red emission is represented by a characteristic spectrum independent of the catalyst used. This observation eliminates the possibility of a metal-containing emitter. A consideration of Cl2, ClO2.O2, Cl2O2, and O4 as possible emitting species is given. Experimental red spectra obtained show a series of fringes which may be caused by quantum interference in a bound-free transition© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Presentation des spectres de rotation magnetique. Observation de la fluorescence de bande large a partir des niveaux perturbes de A 1 Σ u + ∼b 3 Π u . Comparaison de la methode d'analyse de rotation magnetique et d'autres methodes pour la fluorescence

Ion-dip spectroscopy, a variant of stimulated-emission pumping, previously allowed us to characterize the rotational structure of the fast-predissociating species NH3A˜1A2″ By using the vibronic levels of the A level as the intermediate state in a straight optical–optical double-resonance multiphoton ionization method, we obtained new spectra of the ND3B˜1E″ν3, ν4, and ν3 + ν4 vibronic levels. Spectral assignment, including rotational analysis, was made, in which direct, convincing experimental evidence of the Jahn–Teller effect for the B˜ν3 and ν4 modes is presented for ND3. The Jahn–Teller coupling parameters are approximately λ3 ≈ 0.043 and λ4 ≈ 0.060, respectively.

The technique, Perturbation Facilitated Optical-Optical Double Resonance, has provided spectroscopic access to and molecular constants for the 3 3 Σ g + ( v = 1–9), 2 3 Π g ( v = 0–24), 1 3 Δ g ( v = 3–14), b 3 Π u ( v = 0–17), and a 3 Σ u + ( v = 0–6) states of the 6 Li 2 molecule. Perturbation Facilitated Optical-Optical Double Resonance takes advantage of two weak spin-orbit perturbations, A 1 Σ u + ( v = 2, J = 33) ∼ b 3 Π u ( v = 9, F 1 , N = 32) and A 1 Σ u + ( v = 9, J = 20) ∼ b 3 Π u ( v = 15, F 1 , N = 19), to excite from X 1 Σ g + ( v = 0 or 1) into single rotation-vibration levels of 3 Λ u ( F 1 fine structure component only) via the spin-mixed intermediate levels. The 3 Λ u ( F 1 only) states are sampled in resolved fluorescence spectra from Perturbation Facilitated Optical-Optical Double Resonance-populated 3 Λ g levels.

6 Li 2 1 3 Δ g (F 1 ) → b 3 Π u (F 1 v = 0–11) rotationally resolved fluorescence spectra are recorded following perturbation-facilitated optical—optical double resonance excitation of 1 3 Δ g via spin—orbit mixed A 1 Σ + u ∼ b 3 Π u (F 1 e) intermediate levels. The f-symmetry Λ-components of b 3 Π u (F 1 ) are broadened above the 0.05 cm −1 detection threshold owing to predissociation by the vibrational continuum of the a 3 Σ + u state. The observed v = 0–11, N = 31f level widths were used to determine the potential energy curve for the Li 2 a 3 Σ + u state in the region 2.35 R E −1 (relative to E = 0 at the minimum of X 1 Σ + g ). The a 3 Σ + u ∼ b 3 Π u curve crossing is at R = 2.57 A and E = 11246 cm −1 and the electronic part of the − B N·L L -uncoupling matrix element is 〈b Π¦ L + ¦aΣ〉 = 1.216 H at an R -centroid Rv b ϵ a = 2.61A.

Rotationally resolved 6Li2 2 3Πg→a 3Σ+u fluorescence spectra have been obtained by perturbation facilitated optical–optical double resonance spectroscopy. Principal molecular constants for the a 3Σ+u first excited state of 6Li2 are (2σ uncertainties): Te =8180.9±5.4 cm−1, ωe =73.0±1.4 cm−1, ωexe =3.95±0.14 cm−1, Re =4.13±0.08 A, and De =336.0±5.4 cm−1. Transitions into 0≤v≤6 and N=18, 20, 31, 33 were observed and the total number of bound rotation–vibration levels was computed to be 193 for the a 3Σ+u state of 6Li2.

The 6 Li 2 A 1 Σ u + υ A = 2, J = 33 and υ A = 9, J = 20 levels are shown to be spin—orbit perturbed by the b 3 Π u υ b = 9, F 1 e N = 32 and υ b = 15, F 1 e N = 19 levels from which an electronic matrix element of 3 Π oc | H SO |A 1 Σ + > = 0.114±0.006 cm −1 is determined. Previous estimates of this quantity are shown to be incorrect. Although the main and extra levels are separated by less than the 900 K Doppler width of A 1 Σ u + − X 1 Σ g + rotational lines, sub-Doppler intermodulated fluorescence and perturbation-facilitated optical—optical double resonance spectra allow direct observation of the separation of main and extra levels. The mixing coefficients and other perturbation parameters are inferred from a steady state kinetic model of the composite main plus extra lineshape.

With a view to upgrading the diagnostics of supersonic mixing cw chemical laser flowfields, two improved methods have been developed. The improved LIF method is noted for its capability to display the whole cold flowfield and to obtain distinct shock wave patterns with a spatial resolution normal to the incident laser beam higher than 0.5 mm. The second method deals with measuring the spatial intensity profile of the HF overtone emission in a hot reactive flow by using an OMA system. The results should help in elucidating the nature of diffusion between fuel and oxidizer streams in a supersonic chemical laser.