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。     

Screening and Verification of Low Nitrogen Tolerant and Nitrogen Sensitive Cotton Germplasm

[Objective] The aim of this study is to evaluate nitrogen efficient cotton germplasms and improve nitrogen use efficiency. [Method] Eighty cotton germplasms were selected and evaluated in the hydroponic experiment under low (0.25 mmol·L^－1) and high (5 mmol·L^－1) nitrogen concentration. Different traits for screening were identified and nitrogen use efficiency types were classified. Field experiments were also performed for comparison and confirmation of the identified germplasms. [Result] The results showed that there were significant differences in the total plant dry matter, shoot nitrogen accumulation and nitrogen absorption efficiency in cotton germplasms at the two nitrogen levels. Based on coefficient of variation, principal component analysis and correlation, six traits including total plant dry matter, shoot dry matter, root dry matter, total nitrogen accumulation, shoot nitrogen accumulation and nitrogen absorption efficiency were used as screening indicators. According to the Heatmap clustering analysis and the nitrogen efficiency comprehensive index, two germplasms (Lu05R59 and CCRI 69) were identified as low nitrogen tolerant and nitrogen efficient, and two germplasms (Coker 201 and Xinluzhong 30) as low nitrogen sensitive and nitrogen inefficient. The results of field experiment were consistent with the results of the hydroponic culture at the seedling stage. [Conclusion] It was finally determined that Lu05R59 and CCRI 69 were the low nitrogen tolerant and nitrogen efficient germplasms, and Coker 201 and Xinluzhong 30 were low nitrogen sensitive and nitrogen inefficient germplasms. The results of these studies provide the possibility for screening and rapid identification of nitrogen use efficiency in cotton at the seedling stage, and provide the ideal materials and theoretical basis for further study of cotton nitrogen efficient.     

风化煤对农田土壤重金属汞的钝化修复

风化煤钝化修复土壤主要是其活性官能团与重金属发生络合、鳌合等一系列反应,进而降低重金属在土壤中的可迁移性和生物有效性,以达到修复土壤的目的。本文系统研究了风化煤对重金属汞(Hg)的吸附特性及其对Hg在土壤中径向迁移和生物可利用性的影响。结果显示:风化煤对酸碱有一定的缓冲作用,pH对Hg的平衡吸附量影响不大,最大吸附量为8.19 mg/g,该吸附为吸热反应。风化煤对Hg的吸附作用采用Freundlich方程描述较好,为多分子层吸附,吸附动力可用拟二级速率方程描述。土柱试验中风化煤用量为1、2、4、8 g时,淋溶液中Hg含量分别下降2.62、1.66、1.10、0.70μg/g,风化煤的使用可以降低Hg从土壤向溶液的迁移。盆栽试验进一步验证了风化煤对土壤中Hg迁移的阻控作用,其中添加风化煤黄壤中移栽30 d和70 d收获的白菜叶中Hg含量较未添加风化煤黄壤中下降了0.14μg/kg和0.09μg/kg;添加风化煤和外源Hg黄壤中Hg含量是未添加风化煤黄壤的2.4倍,而收获的30、70d小白菜叶中Hg含量前者分别为0.53、0.82μg/kg,后者分别为0.35、0.48μg/kg,理论上可认为前者较后者分别下降了0.31、0.33g/kg。可见,风化煤实现了对土壤中Hg的吸附、钝化,减缓了其生物可利用性,是一种廉价高效的环境友好型钝化剂。     

Interacting effects of yak dung deposition and litter quality on litter mass loss and nitrogen dynamics in Tibetan alpine grassland

The effects of grazing‐induced dung deposition on plant growth and soil attributes are well established, but little is known about dung effects on litter decomposition. Here, we tested effects of yak dung on litter decomposition and nutrient content in a Tibetan alpine meadow. We incubated litter of four common alpine meadow species using litter bags in the field. Two low‐quality species (Kobresia capillifolia and Elymus nutans) with low nitrogen (N), high C/N and Lignin/N, and two high‐quality species, (Saussurea nigrescens and Thermopsis lanceolata) were incubated in monoculture with and without dung addition. Mass loss of leaf litter, fibre fraction (cellulose, hemi‐cellulose and lignin), N and phosphorus (P) were measured after 6, 12 and 18 months of incubation in the field. Dung addition significantly increased decomposition constants for low‐quality litter species, but not for high‐quality litter species. Dung addition promoted cellulose and hemi‐cellulose loss, but lignin loss was not affected by dung addition, except after 12 months for high‐quality litter species. Dung reduced N immobilization after 6 months and did not affect subsequent release in low‐quality litter species, and promoted N release after 6 and 12 months in high‐quality litter species. Regardless of litter quality, dung increased P release after 6 and 12 months. Our results suggest grazing‐induced dung deposition may accelerate C and nutrient turnover, primarily through increasing the mass loss of low‐quality litter, P release from litter and N release from high‐quality litter. The mechanisms underlying the effects of dung deposition need to be clarified in future studies.     

科尔沁沙地典型沙丘植被光谱特性

采用Field Spec4(美国ASD)的便携式光谱仪对科尔沁5种典型沙丘植被的光谱曲线进行测量,并对其特征进行提取分析。结果表明,1)5种典型沙丘植被黄柳(Salix gordejevii)、冷蒿(Artemisia frigida)、麻黄(Herbal ephedrae)、差巴嘎蒿(Artemisia halodendron)和小叶锦鸡儿(Caragana microphylla)的光谱形态大致相同。根据原始光谱差异和多个光谱特征参数可以区分植被类型。"红边斜率"由高到低依次为冷蒿(0.99%)小叶锦鸡儿(0.68%)黄柳(0.59%)麻黄(0.58%)差巴嘎蒿(0.56%)。2)对差巴嘎蒿不同季节光谱反射率特性进行比较分析得知,随植被生长期推移,差巴嘎蒿呈现出"双峰"和"红移"现象,但该现象并不明显。由于研究区在7月份出现持续干旱,植被缺水严重,导致差巴嘎蒿的"红边位置"在7月6日出现微小浮动,显现两个"红边平台"。3)分析不同覆盖度下差巴嘎蒿的光谱特性,差巴嘎蒿的导数光谱呈现"双峰"特性,且当覆盖度大于40%时,"红边位置"与覆盖度并无直接联系,但"红边斜率"与覆盖度呈正比关系。对不同覆盖度下差巴嘎蒿光谱可见光波段的连续统去除,得到吸收深度随覆盖度的增加而增大,吸收峰面积随覆盖度的增加而减小,对覆盖度敏感性参数比较可知,研究该地区差巴嘎蒿覆盖度变化优先考虑吸收峰面积。因此,基于植被高光谱特性的分析,对于今后利用遥感监测沙丘植被长势、植被分类识别及反演植被覆盖度等的应用提供重要的参考价值。     

基于主成分分析和Copula函数的灌溉水利用系数影响因素研究

以新疆生产建设兵团第十二师中型灌区为研究对象，采用首尾法测算2018年和2019年4个样点灌区的灌溉水利用系数，在采用主成分分析法对指标体系降维处理的基础上，用Copula函数构建PCA-Copula评价分析方法，对灌溉水利用系数各影响因素的影响程度和影响规律进行计算分析。结果表明：两年测算数据表明，4个样点灌区灌溉水利用系数都在0.63以上，且最大值达到0.668，分别高于同期全疆、全国平均水平5.05%、10.15%；主成分分析得出，渠道衬砌率（0.944）、滴灌灌溉面积比（0.746）、作物需水量（0.635）、实际灌溉面积（0.734）等都具有超过60%的正贡献率，而葡萄种植比（-0.586）和灌区毛灌溉用水量（-0.645）等具有超过58%的负贡献率。利用PCA-Copula分析评估方法得出，作物种植比例和节水灌溉工程状况对十二师中型灌区灌溉水有效利用系数影响显著（P<0.05），其中葡萄净灌溉定额和灌区毛灌溉用水量对灌溉水有效利用系数的影响极其显著（P<0.01），相关系数分别为0.875、0.742，同时利用Spearman等级相关系数检验法和线型回归来检验PCA-Copula评价法与熵值法的密切程度，检验结果其相关系数分别为 0.87（P＜0.05）和0. 52（P＜0.001），表明PCA-Copula评价方法适用于研究灌溉水利用系数影响因素。     

面包面团发酵性能研究

面团的发酵性能直接影响面包的品质,本研究考察了酵母、糖和食盐用量对面包面团发酵性能的影响,分析了面团在发酵过程中pH值和体积的变化。通过试验发现,面团的发酵速度与酵母和糖的用量成正比,但是过多的酵母和糖均会降低面团的持气性;加入一定的食盐会抑制面团的发酵,而适量的食盐却能在一定程度上改善面团的持气性。通过酵母、糖、食盐的配比试验发现,当酵母添加量为1.0%、糖添加量为10%、盐添加量为10%时,面包面团具有最佳的发酵效果和持气性。     

盐胁迫对羽衣甘蓝种子萌发的影响

为探明盐胁迫对羽衣甘蓝种子萌发特性的影响，明确种子萌发期对盐胁迫的耐受能力，本试验以羽衣甘蓝种子为试验材料，研究不同浓度的NaCL（0、40、80、120、160、200mmol/l）和NaHCO（3 0、20、30、40、50、60mmol/l）对种子萌发胁迫的作用。结果表明:1、2 种盐胁迫处理下，羽衣甘蓝种子的发芽率、发芽势、发芽指数和活力指数等指标均随着盐浓度的升高逐渐降低；2、高浓度的NaHCO³盐溶液对羽衣甘蓝种子的胚根、胚芽的生长抑制较NaCL 盐溶液显著；3、2 种盐     

基于高通量测序分析牛粪堆肥中细菌群落动态变化

文章以奶牛粪便和玉米秸秆作好氧堆肥,堆肥持续36 d。采用16S rRNA基因高通量测序技术分析堆肥过程中细菌群落特征,通过Alpha多样性分析、样本层级聚类分析和距离热图(Heatmap)分析,结果表明,堆肥过程中细菌群落结构发生显著变化。门分类水平细菌群落结构分析表明,变形菌门(Proteobacteria)和厚壁菌门(Firmicutes)在堆肥前期和高温期相对丰度较高,酸酐菌门(Acidobacteria)在堆肥后期相对丰度较高;属分类水平细菌群落结构分析表明,在堆肥初始阶段各属相对丰度相近,环脂酸芽孢杆菌属(Tumebacillus)在堆肥升温期占优势,肠杆菌属(Enterobacter)、未命名细菌(norank_c_OPB54)和玫瑰弯菌属(Roseiflexus)为堆肥高温期优势类群,类似芽球菌属(Blastocatella)出现在堆肥高温期末期,在降温期和腐熟期成为优势菌属。Spearman相关性分析表明,除肠杆菌属(Enterobacter)、未命名细菌(norank_c_OPB54)、假黄色单胞菌属(Pseudoxanthomonas)外剩余11个属均与含水率、有机物降解率、C/N和NH_4~+-N/NO_3~--N之间呈显著相关,肠杆菌属与pH呈极显著正相关(P0.001),未命名细菌(norank_c_OPB54)与温度呈极显著正相关(P0.001)。研究表明,在牛粪堆肥期间细菌群落结构发生显著变化,细菌群落结构变化与堆肥理化因子存在相关关系。     

不同群体中华鳖的形态多样性分析

对长江口、太湖和洪泽湖3个不同区域的中华鳖野生群体的16项生物形态特征进行测量,利用多元统计分析方法对其进行形态多样性差异的比较研究。聚类结果显示,长江口群体和太湖群体首先聚类,再与洪泽湖群体聚合;主成分分析中,共得到了3个主成分,其贡献率分别为56.208%、10.894%和7.165%,累积贡献率为74.267%,其种间形态差异主要取决于头部的一些形态特征;判别分析中,洪泽湖群体、太湖群体和长江口群体的判别准确率分别为100%、100%和93.3%,平均为97.8%。试验结果表明,在3个中华鳖群体中,长江口群体与洪泽湖群体之间分类水平已经达到亚种以上,而长江口群体和太湖群体还未达到亚种水平,说明采用形态差异多元分析进行中华鳖种间遗传多样性研究的可行性,同时也为种质保护和遗传育种提供了一定的理论基础。