微生物素在果蔬采后保鲜中的应用进展

微生物素在果蔬采后保鲜中有重要的应用价值,但目前实际应用在果蔬采后保鲜领域中的并不多。本文分析了目前已经应用到果蔬保鲜领域的微生物素种类,有乳酸链球菌肽、溶菌酶、木霉发酵液等,分析了其抑菌保鲜原理及研究现状;并结合微生物素的特点,提出了微生物素在未来果蔬采后保鲜中的发展趋势,即面对冷藏技术使用不完善的现象,可以开发利用更多的微生物素种类,如纳他霉素、红曲霉素、短梗霉多糖等,为今后果蔬采后保鲜领域的健康可持续发展提供参考。     

世界溶解浆生产消费情况及未来发展趋势

文中总结分析了1961—2017年世界溶解浆生产和消费情况。溶解浆的生产和消费呈现由发达国家（地区）向发展中国家（地区）转移的趋势短期内不会改变。溶解浆生产属于技术和资金密集型产业，随着中国和印度等发展中国家制浆造纸工业的技术进步，溶解浆的生产量将增加，进口占比逐年降低。世界溶解浆的生产和消费量在今后若干年内仍呈增长趋势。2017年世界溶解浆的消耗量为792.9万t，进口量占比为64.3%。乐观预测到2030年世界溶解浆消费量将达到1 230万t，在2017年的基础上增加60%。中国是世界最大的溶解浆生产国、进口国和消费国，但溶解浆的生产成本居高不下，浆料品质不够稳定，与先进国家存在一定差距。亟待投入研究力量，开发适宜的溶解浆生产工艺，提升溶解浆质量并降低生产成本。     

长期少免耕对中国东北玉米农田土壤呼吸及碳氮变化的影响

在黑土区37年不同耕作模式定位试验田，采用原位法比较常规旋耕灭茬起垄（CT）、旋耕留高茬行间深松-少耕（RT）、免耕（NT）和深翻（PT）4种耕作模式土壤呼吸速率及其与土壤温度和湿度的关系，测定土壤总碳氮、无机氮，微生物碳氮的变化。结果表明，玉米生育期间土壤呼吸呈单峰变化，开花期达最大值，生长季平均呼吸速率依次为RT > NT > CT > PT。4个处理土壤温度与土壤呼吸速率间存在显著指数关系。不同耕作模式0~10 cm土壤温度可解释土壤呼吸速率变异的38.3%~67.9%，温度敏感性系数Q10范围为2.1~5.3；RT和NT处理显著提高0~20 cm土壤碳氮含量；RT处理在0~20 cm土壤中微生物碳含量均高于CT、NT和PT处理。RT处理土壤呼吸对温度响应提高，RT和NT处理显著增加上层土壤总碳氮含量，利于土壤质量提升。     

油菜角果数量及关键表型参数的自动化检测方法研究

为有效替代人工方式考种油菜、观测角果,研究了一种用于测量批量角果的数量和关键表型参数的自动化检测方法。设计了角果散铺和图像采集装置,利用拨动加振动的方式将堆积角果均匀散开并拍摄视频;使用二维码作为标记块,以有效地提取关键帧并拼接为包含全部角果的整幅图像;提出了基于凹点提取与匹配的图像分割方法,分割各种形态下的重叠角果,准确率达到98%以上。在关键表型参数测量中,利用了最大类间方差法以判断角果的正置或侧置姿态,以此估计角果横切面的近似椭圆长短轴,再计算角果的长度、表面积和体积。实验结果表明该方法具有很好的检测精度,对不同品种的油菜适应性较好,长度、表面积和体积的估计误差分别不大于2.9%、4.8%和5.0%。该方法可以有效替代人工方式的油菜考种,为相关农业科研领域提供基础数据。     

Identification of culturable microbial functional groups isolated from the rhizosphere of four species of mangroves and their biotechnological potential

This study identified microbial functional groups like total culturable bacteria, potential N₂-fixing free living bacteria, N₂-fixing hydrocarbonoclastic bacteria, N-assimilating hydrocarbonoclastic bacteria, total fungi, actinobacteria, P-solubilizers, lipolytic microorganisms, and starch, cellulose, pectin and protein degrading microorganisms, isolated from the rhizosphere of four species of mangroves (Red, Black, White, and Button) from the natural protected area at the Terminos Lagoon, Campeche, México. Overall, microbial populations showed significant differences (P < 0.05) among the four mangrove species. The rhizosphere of White mangrove showed better chemical and textural soil properties, and harbored the highest microbial populations when compared to the remaining mangrove species. The principal component analysis indicated that two components accounted the 85.3% of the total variation. The most significant textural and chemical soil properties were the major components, CP1 (organic matter and total organic carbon) and CP2 (sand and clay). Microbial populations correlated (P < 0.05, Pearson coefficient) with sand and clay particles, and with some soil chemical properties such as organic matter. The total nitrogen and organic carbon significantly correlated with cellulose degraders, while phosphorus with N₂-fixing bacteria, total fungi, and with pectin and starch degraders.     

Artificial neural network modeling of microbial community structures in the Atlantic Forest of Brazil

Microbial communities vary across the landscape in forest soils, but prediction of their biomass and composition is a difficult challenge due to the large numbers of variables that influence their community structures. Here we examine the use of artificial neural network (ANN) models for extraction of patterns among soil chemical variables and microbial community structures in forest soils from three regions of the Atlantic Forest of Brazil. At each location, variations in soil chemical properties and FAME profiles of microbial community structures were mapped at 20 × 20 m intervals within 10 ha parcels. Geostatistical analyses showed that spatial variability in soil physical and chemical variables could be mapped at scale distances of 20 m, but that FAME profiles representing the microbial communities were highly variable and had no spatial dependence at the same scale in most cases. RDA analysis showed that FAME signatures representing different microbial groups were positively associated with soil pH, OM, P and base cations concentrations, whereas microbial biomass was negatively associated with the same environmental factors. In contrast, ANN models revealed clear relationships between microbial community structures at each parcel location, and generated verifiable predictions of variations in FAME profiles in relation to soil pH, texture, and the relative abundances of base cations. The results suggest that ANN modeling provides a useful approach for describing the relationships between microbial community structures and soil properties in tropical forest soils that were not able to be captured using geostatistical and RDA analyses.     

High clay content accelerates the decomposition of fresh organic matter in artificial soils

Clay is generally considered an important stabiliser that reduces the rate of decomposition of organic matter (OM) in soils. However, several recent studies have shown trends contradicting this widely held view, emphasising our poor understanding of the mechanisms underlying the clay effects on OM decomposition. Here, an incubation experiment was conducted using artificial soils differing in clay content (0, 5, and 50%) at different temperatures (5, 15, and 25 °C) to determine the effects of clay content, temperature and their interaction on fresh OM decomposition. CO₂ efflux was measured throughout the experiment. Phospholipid fatty acids (PLFAs), enzyme activities, microbial biomass carbon (MBC), and dissolved organic carbon (DOC) were also measured at the end of the pre-incubation and incubation periods in order to follow changes in microbial community structure, functioning, and substrate availability. The results showed that higher clay contents promoted OM decomposition probably by increasing substrate availability and by sustaining a greater microbial biomass, albeit with a different community structure and with higher activities of most of the extracellular enzymes assayed. Higher clay content induced increases in the PLFA contents of all bacterial functional groups relative to fungal PLFA content. However, clay content did not change the temperature sensitivity (Q₁₀) of OM decomposition. The higher substrate availability in the high clay artificial soils sustained more soil microbial biomass, resulting in a different community structure and different functioning. The higher microbial biomass, as well as the changed community structure and functions, accelerated OM decomposition. From these observations, an alternative pathway to understanding the effects of clay on OM decomposition is proposed, in which clay may not only accelerate the decomposition of organic materials in soils but also facilitate the SOM accumulation as microbial products in the long term. Our results highlight the importance of clay content as a control over OM decomposition and greater attention is required to elucidate the underlying mechanisms.     

清凉峰自然保护区华南梅花鹿种群数量与分布研究

于2006年1—3月,采用雪地足迹计数法和样带法对清凉峰国家级自然保护区内野生华南梅花鹿种群与分布进行调查研究,结果表明,在38条样带中有13条样带发现有华南梅花鹿,这13条样带构成一个狭长地带;清凉峰自然保护区内野生梅花鹿种群最低密度为0．90头／km^2,最高密度为2．79头/km^2,平均密度为1．84头／km^2,种群数量为104（51～156）头。研究揭示,华南梅花鹿主要在海拔800-1200m的范围内活动,栖息地植被类型以草甸和灌丛为主。     

杉木干基萌芽能力的遗传变异

分析了两片杉木子代林伐桩和杉木无性系采穗圃萌条数量的遗传变异情况。结果表明：杉木子代林伐桩萌条数量在产地间、产地内家系间及组合间均存在极显著差异，并有中等以上遗传力；遗传变异系数在３７％～３９％之间；产地的遗传方差分量与产地内家系间的相近。伐桩萌条数量与基径粗度的关系随伐桩年龄的变化而表现不一；不同砍伐季节伐桩萌条数量也存在较大差异。杉木无性系采穗圃无性系间有效萌条数量存在极显著差异，无性系的萌芽能力有较高的重复力。     

低海拔地区浙江红花油茶无性系的开花物候特性

为研究低海拔区域浙江红花油茶无性系开花物候特性,对浙江金华东方红林场的22个浙江红花油茶无性系开花物候、花期长短、开花数量进行了调查观测。结果表明:低海拔地区浙江红花油茶无性系花期始于1月下旬,结束于4月中下旬,花期长达62.5 d,花期较集中,但开花期容易受到气候的影响。不同浙江红花油茶无性系开花物候差异显著,开花期最早的是无性系dy144,最晚的是无性系hy31。花期持续时间最长的是无性系hy54、hy179,花期持续时间均值为53.5 d;最短的是无性系hy58,花期持续时间均值为26.5d。22个无性系之间开花数量存在极显著差异(P<0.01)。根据本试验的研究结果,其中无性系dy156、hy8、hy28、hy31、hy43、hy47、hy59、hy63、hy54、hy71、hy179可以考虑作为园林观赏推广品种。