Genotypic differences in storage losses of sugar beet – causes and indirect criteria for selection

To improve the storability of sugar beets, this study aimed at determining reasons for genotypic variability in sugar losses and invert sugar accumulation during storage, and at identifying indirect criteria to select for varieties with low storage losses prior to storage. In 2011 and 2012, 18 genotypes, and in 2012 and 2013, six genotypes cultivated at two locations were stored for 8 and 12 weeks at 8°C under controlled conditions. The same 18 genotypes were grown under stress conditions in Spain in 2012/2013. Sugar losses were closely correlated with the invert sugar accumulation after storage. Genotypic differences in storage losses were primarily caused by differences in the level of infestation with microorganisms. The invert sugar accumulation was lower for genotypes with high marc concentration before storage, pointing to a non‐specific resistance. Additionally, the sugar concentration in dry matter before storage, and the invert sugar concentration after cultivation under stress conditions correlated with the invert sugar concentration after storage. These parameters are therefore suggested as criteria to select for improved storability of sugar beet genotypes.     

真空预冷压力对双孢菇贮藏效果的研究

以双孢菇为试材,研究其在0℃经不同真空预冷终压(0.1、0.3、0.5 k Pa)预冷后,在常压(0.1 MPa)(0±1)℃下的贮藏效果。结果表明,预冷压力对双孢菇预冷后的失重率有显著影响,随着预冷压力的降低失重率升高;与未预冷组相比,真空预冷可有效抑制双孢菇的褐变、萎蔫和细胞膜渗透率的增长,但预冷压力对细胞膜渗透率和褐变影响不明显;真空预冷和预冷压力对开伞度无明显影响;真空预冷和预冷压力对双孢菇呼吸强度和萎蔫程度影响显著,0.3 k Pa组双孢菇样品的呼吸高峰较其他组均延迟,且贮藏结束时的萎蔫程度远小于0.1 k Pa组样品。综合分析得出,双孢菇的最佳预冷压力为0.3 k Pa,此结论为双孢菇的贮藏应用提供了一定的理论参考。     

预冷对海南北运冬瓜冷链运输品质的影响

以海南北运冬瓜为试材,采用4℃冷库对其进行预冷处理,研究不同预冷时间(2、4、6、8 h)对冬瓜果肉温度和质构指标的影响,并对预冷(4℃冷库预冷4 h)及未预冷冬瓜在模拟冷链运输(15℃)过程中的失重率和质构指标进行研究。结果表明,冬瓜在4℃冷库的最佳预冷时间为4 h,果温可从23.6℃降至6.5℃;预冷能够有效控制冬瓜冷链运输过程中的失重,延缓硬度、弹性和咀嚼性指标的下降。     

吉林省主要粮食作物生产风险评价

充分认识吉林省主要粮食作物生产面临的风险,为稳定粮食产量和保障国家粮食安全提供参考。以县级行政单元为研究对象,在运用直线滑动平均法对作物单产进行趋势模拟的基础上,运用非参数信息扩散模型对吉林省玉米、水稻和大豆3种主要粮食作物的生产风险进行了评估。结果表明:不同类型作物生产所面临的风险大小不同,单产损失风险从大到小依次为大豆、玉米、水稻;西北部地区县域的风险普遍较大,其次是东南角地区,而中部地区县域的风险相对较小;吉林省玉米、水稻和大豆3种作物单产损失率30%以上的概率较小。     

雪灾对农业影响的损失评估

为了分析雪灾对宁波市农业影响的损失,并对其进行评估。本研究选取宁波市2014年一次降雪过程,基于自然灾害理论,综合考虑形成雪灾损失的危险性、暴露性、脆弱性和防灾减灾能力,将遥感、地理信息技术与雪灾损失相结合构建雪灾损失评估模型。结合土地利用类型图,提取农业用地,将雪灾对农业影响的损失区域划分为低损失、中损失和高损失,并进行分区评述。结果表明:余姚市的积雪覆盖面积最大,且雪灾各损失等级所占面积均最大,受灾最严重;海曙区、江东区和江北区无积雪覆盖,无雪灾损失。雪灾高损失区域主要位于海拔较高的余姚南部和鄞州西部山区。     

我国三大平原农户储粮减损集成技术

针对我国三大平原气候条件,结合稻谷、小麦、玉米三大主要粮食作物储藏特点,分别提出了适合我国东北、华北和长江中下游三大平原农户储粮减损的集成技术,旨在解决目前我国农村储粮损失巨大的问题,为农户安全储粮提供了技术保障,从而达到农户储粮减损增收的目的.     

Effect of Storage Conditions on Germination in Wheat

The percentage germination was determined for storage of wheat at four grain moisture contents (15, 18, 21 and 24 %), four temperature levels (4, 15, 25 and 40°C) and three levels of mechanical damage (0, 15 and 30 %). The effect of each level of moisture was investigated using three replicates for each temperature and each level of mechanical damage. During storage, at 0.25, 0.5 and 1 % dry matter loss (DML), germination tests were carried out on samples taken from each of the above treatments. The percentage germination was compared statistically amongst treatments. The analysis showed significant differences among most of the treatments. The percentage germination decreased very slowly at a low moisture level (15 %), low temperature (4°C) and low level of damage (0 %), while it decreased rapidly at a high moisture level (24 %), high temperature (40°C) and high level of damage (30 %). For example, the percentage germination was 41 % when the wheat was stored at 4°C, 15 % mechanical damage and 24 % moisture content after a storage time of 36.5 days, while the percentage germination was 88.3 % when the wheat was stored at 4°C, 15 % mechanical damage and 15 % moisture content after a storage time of 104 days.     

The effects of wall parameters on CH4 catalytic combustion in micro-channels

The paper uses CFD simulation to investigate the catalytic surface reaction and heat loss characteristics of premixed CH4/air in micro-channels with Platinum catalyst. A 3D model is used with the detailed surface elementary reaction mechanism, which includes the coupled heat transfer of wall and flow domain, solid wall thermal conductivity and the convection and surface radiation between wall and the environment. The results show that the thermal conductivity has a big impact on the uniformity of wall temperature. The convective heat transfer coefficients and the surface emissivity are the key factors to determine the external heat loss of micro-combustor. An increase of wall depth can reduce the external heat loss per unit area, but it increases the total heat loss. The change of the amount of heat loss changes the reaction rate and residence time of mixed gas in the channel, which affect the methane conversion. The research indicates that the material with bigger thermal conductivity is better to fabricate micro-combustors, and the multi-methods are needed to reduce the wall heat loss.     

中国南方喀斯特地区水土流失特殊性研究

近20年来,人们对中国南方喀斯特地区的研究日渐深入,在石漠化已成为研究热点的今天,笔者提出应当强调该地区水土流失的特殊性这一基本条件。以其特殊性为出发点,才能科学地认识该地区水土流失的本质和危害性。中国南方喀斯特地区特殊的水土流失是诸多因素造成,地质背景是特殊性产生的前提条件,气候背景是特殊性产生的重要原因,自然因素的特殊性是水土流失特殊性产生的直接原因,人文因素对水土流失的产生有巨大驱动作用。石漠化是这一地区特殊水土流失的结果。其特殊性的研究意义在于获得适用于该地区水土流失特点的评价标准、研究方法和防治手段,最终指导石漠化防治工作。     

Combined effects of sodium chlorite dip treatment and chitosan coatings on the quality of fresh-cut d’Anjou pears

This study evaluated the effects of sodium chlorite (SC) alone and its sequential treatment with edible coatings on browning inhibition and quality maintenance of fresh-cut d’Anjou pears. Edible coatings were prepared from chitosan (CH) and its water-soluble derivative carboxymethyl chitosan (CMCH), separately. Pear wedges were immersed in SC solution, followed by coating with CH or CMCH solutions. The samples were packed in unsealed bags and stored at 4 °C for subsequent color, firmness, and weight loss measurement. The effects of the SC and coating treatments on polyphenol oxidase (PPO) inhibition and microbial inactivation were also evaluated. Results indicated that SC exhibited significant (P < 0.05) inhibition of browning and PPO activity. The SC treatment was also strongly effective in inactivating Escherichia coli O157:H7 on pear slices. Coating SC-treated pear slices with CH adversely affected the quality of pear slices by accelerating the discoloration of cut surfaces and increasing the PPO activity. On the contrary, coating SC-treated samples with CMCH significantly prevented the browning reaction and inhibited PPO activity. In addition, SC and CH/CMCH coatings maintained tissue firmness and did not affect weight loss. Our study may provide a scientific basis for the use of SC + CMCH treatment as an alternative preservation treatment for fresh-cut fruits and vegetables.