间歇升温对芒果冷害及生理生化反应的影响

对低温贮藏中的芒果进行间歇升温处理，结果表明：间歇升温处理延迟了２℃贮藏果冷害引起的乙烯释放及呼吸强度的上升，延迟了果皮多胺水平的上升，使果皮的ＳＯＤ活性维持在较高水平，细胞膜透性增加缓慢，从而显著提高了芒果的抗冷害能力。但间歇升温处理使１０℃贮藏果乙烯释放高峰及呼吸高峰提前且峰高增加，果皮ＳＯＤ活性降低，果皮细胞膜透性增大，从而促进了芒果的成熟衰老。     

Analysis of variation and interrelationships in potato germplasm

Summary As the exploitation of economic characters in potato is reaching a plateau, use of exotic germplasm offers an ideal opportunity for further improvement. Fifty-five accessions from eleven countries were studied under long and short day conditions. Wide variation was noticed for a number of phenological, morphological and tuber characters. Analysis of variation and correlations has demonstrated possibilities for using this diverse germplasm in various potato improvement programs.Abbreviations APC - Andean Primitive Cultivars - AUDPC - Area Under Disease Progress Curve - CCBL - Commerical Cultivars and Breeding Lines - LD - Long Days - SD - Short Days     

Genetic diversity of potato landraces from northwestern Argentina assessed with simple sequence repeats (SSRs)

Andean potato varieties are cultivated in the northwest of Argentina and constitute the most important staple food for the local farmers. The genetic diversity of 155 accessions conserved at the Genebank of Balcarce (INTA) was tested using four microsatellites. Three commercial potato varieties of Tuberosum group and one accession of Curtilobum group were used as outgroups. The presence of bands was scored for each microsatellite and for each accession and the data were analysed by principal coordinate analysis. The polymorphism information content was obtained for each molecular marker from banding patterns. Analysis of molecular variance was carried out with a variable number of accessions for each landrace, from different departments and sites within departments. More than one genotype was detected in the majority of the potato landraces. Some accessions within each landrace did not differentiate. AMOVA revealed that most of the genetic variation occurred among sites within departments and among local varieties. These findings are discussed considering the agricultural practices carried out in the Andean farming system.     

热处理降低哈密瓜果实活性氧代谢减轻冷害

为探讨热处理能否激发哈密瓜果实抗冷性,减轻冷害。该文以"西州密25号"哈密瓜为原料,在已有研究的基础上,将哈密瓜在55℃热水中浸泡3 min,以室温(22±2)℃清水浸泡3 min为对照,待其表面水分完全晾干以后,放置于3~5℃机械冷库中贮藏,测定贮藏期间哈密瓜品质及生理指标。结果表明,与对照相比,热处理诱导哈密瓜果肉过氧化氢H_2O_2和超氧阴离子O_2~-含量短暂增加,但明显减少贮藏中后期(14~35 d)H_2O_2,O_2~-的积累(P0.05),提高活性氧清除酶过氧化物酶和超氧化物歧化酶的活性(P0.05),抑制细胞膜相对渗透率和丙二醛含量上升,降低贮藏后期的冷害发生率(P0.05),缓解果实可溶性固形物和抗坏血酸含量下降(P0.05),保持果实较好的品质。热处理主要通过诱导活性氧信号分子,提高活性氧清除酶活性、减少膜脂过氧化作用,从而减轻果实的冷害。研究结果为哈密瓜采后贮藏技术提供理论参考。     

新型鲜切果蔬杀菌技术研究进展

鲜切果蔬是一种新型的安全、绿色、环保的果蔬产品,符合现代社会对健康食品的要求,有很大的发展前景。杀菌是保证鲜切果蔬品质安全的重要环节,目前应用最多还是含氯杀菌剂,但因其含有诸多弊端,因此新型的替代杀菌技术得到了广泛的研究。从新型化学杀菌技术、物理杀菌技术和生物杀菌技术3方面,系统总结了近些年出现的取代含氯杀菌剂的新型鲜切果蔬杀菌技术,阐述了新型杀菌技术的杀菌效果及其优缺点,并对其未来的应用前景进行了展望。     

果脯中SO2残留量与硫处理方法相关性的研究

果脯生产过程中进行硫处理,能改善成品的色泽,防止褐变。本试验结果表明:果脯经硫处理,成品和糖液中SO_2残留量受亚硫酸盐使用浓度、使用方法、处理时间、原料种类及制作工艺等诸因素的影响。采用0.2％亚酸酸氢钠溶液浸泡果坯8h,或1％亚硫酸氢钠溶液浸泡果坯2h的硫处理方法,可使果脯中SO_2残留量保持在国家标准规定的允许范围内,并对保持和改善果脯色泽,提高产品质量有较好的效果。     

Biocontrol Efficacy of Two Antagonistic Yeasts Against Postharvest Diseases in Peach Fruits During Storage Periods

Two antagonistic yeasts, Thichosporon pullulans and Cryptococcus laurentii, were investigated for their biocontrol potential to blue mold rot and rhizopus rot on harvested peach fruits (Prunus persica L. Batsch, cv. Okubao), alone or in combination with a Iow dose of iprodione (50 μg mi-1 ). The results indicated that T. pullulans and C. laurentii were effective at reducing disease incidence and severity of blue mold rot and rhizopus rot in peach fruits. Biocontrol efficacy of C. laurentii and T. pullulans were significantly enhanced by combination with a Iow dose of iprodione (50 μg mi-1) against blue mold and rhizopus rot in peach fruits. T. pullulans and C. laurentii combined with a low dose of iprodione (50 μg mi-1 ) resulted in better disease control than either iprodione or the yeasts used alone. Dipping fruits in suspensions of antagonist cells showed the similar control effect as the treatment with iprodione (500 μg ml-1 ).     

中国果蔬汁饮料制造业分析及建议

运用传统产业组织理论分析了中国果蔬汁饮料制造业的市场结构、企业行为以及经济绩效。结果表明,我国果蔬汁饮料制造业行业集中度较低,属于垄断竞争型的市场结构。目前市场上尚未形成具有支配性力量的企业,市场竞争激烈,企业间的竞争行为倾向于品牌的构建,同时行业经济绩效呈现增长态势。     

Sensitivity in the estimation of parameters fitted by simple linear regression models in the ratio of blueberry buds to fruits in Chile using percentage counting

Blueberry exporting is an important activity in Chile, with fresh blueberries commanding the highest prices and being among the most exported products to the European and North American markets. To maintain quality in the centres of consumption, farmers must continuously improve the logistics of harvesting and shipping the blueberries. Thus every year they must calculate the production of the orchard well in advance in order to hire staff and ensure the logistic cold chain. For this calculation they use a count of flower buds and a simple linear model of which the slope parameter represents the number of fruits per bud. However, due to the cost of the counting procedure, some producers count only a fraction of each plant (25%, 50% or 100%), and furthermore they do not know what effect the variety and productive age of the plants may have on the estimation. The objective of this work is to measure the impact of the cultivated variety, the age of the plant in productive years, and the percentage of fruits counted in estimating the parameter fruits per bud. The study involved monitoring 310 plants of different varieties and ages distributed in northern, central and southern Chile (over an area of approximately 700 km × 200 km). The parameter was estimated by fitting simple linear regression models (SLRM) as a function of the number of fruits and flower buds. To evaluate the impact on the parameter, the SLRM was fitted considering the variables observed in all the plants, by percentage counted, by variety and by variety-age of the plant. The major findings indicate significant differences in the estimation of the parameter, suggesting that in order to estimate fruits per bud the whole plant must be counted and its age and variety taken into account.     

Pattern of genetic diversity of cultivated and non-cultivated mashua, <Emphasis Type="Italic">Tropaeolum tuberosum</Emphasis>, in the Cusco region of Perú

This paper analyzes the genetic diversity of mashua cultivars grown in six communities in the Cusco region of Perú, of non-cultivated forms collected in the same region, and a sample of cultivars from the germplasm collection at the International Potato Center (CIP). From the DNA fingerprinting generated by SRAP markers, it is clear that mashua is a genetically variable crop with a range of similarity ranging from 65 to 99%. The widest range of variation was found for the most isolated community, Sayllafaya. Another important finding was that most of the non-cultivated accessions are likely feral races resulting from escape to cultivation rather than wild relatives. In general the range of variation of the cultivars from the communities and their feral relatives are not represented in the cultivars sampled of the collection maintained at the International Potato Center, Perú.