Induction of flavonoid production by UV-B radiation in Passiflora quadrangularis callus cultures

Callus cultures from several species of Passiflora were initiated in vitro, and their capacity to produce four glycosyl flavonoids (orientin, isoorientin, vitexin, isovitexin) was analysed. The aim of the present work was to examine the possible role of UV-B irradiation and elicitation with methyl jasmonate (MJ) on the production of these compounds in callus cultures. All the species tested (P. incarnata, P. quadrangularis, P. edulis) formed friable callus from leaf explants after 4 weeks on medium supplemented with kinetin and 2,4-dichlorophenoxyacetic acid. Among them, P. quadrangularis turned out to have a faster growth rate and a more friable texture, and was therefore chosen for experiments with elicitors. In callus cultures only small amounts of isoorientin were found, while the concentration of the other flavonoids was below the detection limit. UV-B irradiation of calluses was able to increase the production of all four glycosyl flavonoids. After a 7-day exposure of cultures to UV-B light, the production of isoorientin reached concentrations similar to those found in fresh leaves from glasshouse-grown plants. Elicitation with methyl jasmonate also enhanced orientin, vitexin and isovitexin concentrations, even though the stimulation was about 6-fold weaker for orientin and vitexin and about 40-fold for isovitexin, than that exerted by UV-B treatment. Callus cultures treated with the UV-B dose which most enhanced flavonoid production showed a higher antioxidant activity compared to untreated calluses, with an increase ranging from 28% to 76%. Results show that the secondary metabolite biosynthetic capacity of Passiflora tissue cultures can be enhanced by appropriate forms of elicitation.     

Influence of methyl jasmonate in conjunction with ethanol on the formation of volatile compounds in berries belonging to the Rosaceae

The effect of methyl jasmonate in combination with ethanol on the formation of aroma constituents in berryfruit belonging to the Rosaceae was investigated. Postharvest treatments of raspberries, strawberries and blackberries were carried out. After evaluating the aromatic fractions of the berries, esters and terpenes were the most abundant compounds. There were different effects of the treatment according to the berry species. In contrast to raspberries, which exhibited a significant decline (p < 0.05) in the total amount of volatiles after treatment, a significant (p < 0.05) enhancement of total volatile compounds was observed in strawberries, while no significant effect was found in blackberries. Esters and terpene compounds responded similarly in strawberries and blackberries suggesting similarity in the biochemistry of their aroma synthesis. In contrast, raspberry volatile compounds showed a different pattern, reflecting different biosynthetic pathways for aroma formation in raspberry. The natural volatile compounds, methyl jasmonate and ethanol, seemed to have either promoting effects on the formation of the (−)-enantiomers of chiral terpenes and ionones or inhibitory effects on the synthesis of the corresponding (+)-enantiomers.     

Microbial community composition and enzyme activities in a sandy loam soil after fumigation with methyl bromide or alternative biocides

A sandy loam soil was fumigated in microcosms for 24 h with methyl bromide and chloropicrin (MeBr+CP), propargyl bromide (PrBr), combinations of 1,3-dichloropropene and CP (InLine), iodomethane and CP (Midas), an emulsifiable concentrate of CP (CP-EC), or methyl isothiocyanate (MITC). The effects of these pesticides on fatty acid methyl ester (FAME) profiles and selected enzymatic activities were evaluated in fumigated soils and a nonfumigated control at 1, 3, 7, 14, 21, 28, and 90 days post-fumigation. Bacterial (a15:0, i15:0, i16:0, cy17:0, a17:0 and i17:0) and fungal (18:2ω6, 18:3ω6, 18:1ω9) FAMEs were initially (1 day post-fumigation) reduced by fumigation with CP-EC, InLine, and Midas. Microbial communities of soils fumigated with MeBr+CP, MITC, and PrBr resembled those of the control soil. At 14-28 days post-fumigation, FAME profiles were changed in all fumigated soils relative to the control, with the exception of soils treated with MITC. At 90 days post-fumigation, FAME profiles suggested that actinomycetes (10 Me 16:0, 10 Me 17:0, 10 Me 18:0) and Gram-positive bacteria may recover preferentially after fumigation with most of the pesticides studied. Among the fumigants tested, InLine, Midas, and CP-EC had a higher potential to alter the microbial community structure in the longer term than MeBr+CP, PrBr and MITC, with MITC having the least effect. Soil enzyme activities in fumigated microcosms were significantly (P≤0.037) different from the nonfumigated soil, with the exception of β-glucosidase in soils treated with PrBr and MITC, and dehydrogenase in MeBr+CP-fumigated soils. Over the 90-day study, soil fumigation (average of all fumigants and sampling dates) reduced the activities of arylsulfatase (62%), dehydrogenase (35%), acid phosphatase (22%), and β-glucosidase (6%), suggesting that S mineralization in soils and the total oxidative potential of microorganisms were more affected by fumigation than P and C mineralization. This study also indicates that soil fumigation with MeBr+CP alternative biocides has the potential to alter microbial communities and important key reactions involved in nutrient transformation.     

SA和MeJA处理对‘鬼椒王’果实胎座辣椒素类物质含量的影响

探究水杨酸（Salicylicacid,SA）和茉莉酸甲酯(Methyl Jasmonate,MeJA)不同浓度处理下‘鬼椒王’果实胎座中辣椒素和二氢辣椒素含量的变化。采用高效液相色谱法（HPLC）,对不同浓度SA和MeJA喷施后的‘鬼椒王’5个生长期的果实胎座辣椒素和二氢辣椒素含量进行测定。结果表明：（1）不同浓度SA和MeJA处理条件下,处理与对照中辣椒素和二氢辣椒素含量呈现出相同的变化趋势,先增加,并在40 d左右（即果实转红期）达到最高,40~50 d含量降低。（2）SA处理中,较低浓度（1.5 mmol/L）的喷施最有利于辣椒素和二氢辣椒素的积累,最大含量分别为98.400 mg/g和5.771 mg/g,而高浓度（2.5、3.5、5.0 mmol/L）的处理显著抑制了辣椒素的积累。(3)MeJA处理下,4个浓度水平的MeJA（1.0、1.5、2.5、3.5 mmol/L）处理均促进辣椒素和二氢辣椒素的积累,其中,在2.5 mmol/L MeJA的处理下,辣椒素和二氢辣椒素达到最大值,分别为116.181 mg/g和7.035 mg/g。本研究为外施SA和 MeJA促进辣椒中辣椒素的含量提供了科学依据。     

樱桃中苹果蠹蛾溴甲烷熏蒸试验研究

试验设11~15℃、16~20℃、21~26℃3个温度区间,试验用苹果蠹蛾幼虫人工接种到樱桃上,分别用4种不同溴甲烷剂量进行处理,每个处理设5个重复,1个对照,试验在温控室的熏蒸桶中进行。结果表明,在11~15℃,溴甲烷剂量48 g/m3,熏蒸2h;16~20℃,溴甲烷剂量40 g/m3,熏蒸2h;21~26℃,溴甲烷剂量32g/m3,熏蒸2h,均能够100%杀死樱桃中苹果蠹蛾幼虫。考虑温度对樱桃品质的影响,建议将11~15℃、溴甲烷剂量48g/m3,熏蒸2h,作为溴甲烷熏蒸樱桃中苹果蠹蛾的技术参数。     

外源调节物质对铬(Cr6+)胁迫下小麦种子萌发的缓解效应

为明确外源调节物质对Cr⁶⁺胁迫下小麦种子萌发的缓解机制,利用水培试验研究了葡萄籽提取物（grape seed extract,GSE）、氯化血红素（hematin chloride,Hemin）和茉莉酸甲酯（methyl jasmonate,MeJA）对Cr⁶⁺胁迫下小麦种子萌发的影响。结果表明,Cr⁶⁺胁迫显著降低了小麦种子发芽率、幼苗根长、株高、干物质积累量及种子α-淀粉酶活性,同时提高了小麦根系渗透调节物质的含量,并引发氧化胁迫。外源GSE、Hemin和MeJA均可有效缓解Cr⁶⁺胁迫对小麦种子萌发的不良影响,促进种子萌发和幼苗生长,提高小麦根系可溶性糖和可溶性蛋白含量,增强α-淀粉酶、超氧化物歧化酶（superoxide dismutase,SOD）、过氧化氢酶（catalase,CAT）、抗坏血酸过氧化物酶（ascorbase peroxidase,APX）和谷胱甘肽还原酶（glutathione reductase,GR）的活性。其中,GSE对Cr⁶⁺胁迫的缓解效果最佳。总之,外源调节物质可以通过提高Cr⁶⁺胁迫下小麦种子萌发过程中的淀粉水解能力、渗透调节能力和抗氧化能力,提高小麦的耐Cr⁶⁺性。     

相转移催化合成甲基葡萄糖苷二油酸酯

以α-甲基葡萄糖苷和油酸甲酯为原料,在四丁基溴化铵(TBAB)和K2CO3的共同催化作用下,无溶剂法合成了甲基葡萄糖苷二油酸酯,并对产品进行了IR表征.探讨了相转移催化酯交换反应机理,考察了原料配比、催化剂种类及用量、反应温度、反应时间等因素对油酸甲酯转化率的影响.最佳工艺条件为:n(甲基葡萄糖苷):n(油酸甲酯)=1.1:2,w(TBAB):w(油酸甲酯)=3.5%,w(K2CO3):w(油酸甲酯)=2.5%,反应温度115-120℃,反应时间4.5 h,反应压力～6 kPa.上述条件下,产品收率可达92%,产品质量较好.     

覆盖不透膜、少用甲基溴的土壤消毒效果及对温室番茄生长的影响

2001~2003年在山东省青州市温室中进行了2次减量甲基溴、覆盖不透膜(VIF膜)土壤消毒试验。在田间相同条件下,用甲基溴对种植番茄的大棚土壤进行消毒处理,分别覆盖不透膜和普通聚乙烯膜(PE膜)。试验结果表明,甲基溴低量处理37.5 g/m2覆盖VIF膜与常规用量50 g/m2覆盖PE膜比较,在对根结线虫病控制、生长特征及产量上均无显著差异。使用VIF膜可显著减少甲基溴渗漏,减少用量25%以上,从而减少对臭氧层的破坏。     

Soil solarization in various agricultural production systems

Soil solarization is a natural, hydrothermal process of disinfesting soil of plant pests that is accomplished through passive solar heating. Solarization occurs through a combination of physical, chemical, and biological mechanisms, and is compatible with many other disinfestation methods to provide integrated pest management. Commercially, it is used on a relatively small scale worldwide as a substitute for synthetic chemical toxicants, but its use is increasing as methyl bromide, the major chemical fumigant, is phased out due to its ozone-depleting properties. Solarization currently is an important and widespread practice for home gardeners. In production agriculture, the principal use of solarization (on a treated area basis), is probably in conjunction with greenhouse grown crops. Another application for which solarization has come into common use is for disinfestation of seedbeds, containerized planting media, and cold-frames. Around the world, solarization for disinfesting soil in open fields is being implemented at a relatively slow but increasing rate. It has been mainly used for commercial production in areas where air temperatures are very high during the summer and much of the cropland is rotated out of production due to excessive heat. As global concerns regarding environmental quality grow along with the human population in the 21st century, concepts such as solarization and other uses of solar energy in agriculture will likely become increasingly important.