Identification,characterization and full-length sequence analysis of a novel endornavirus in common sunflower (Helianthus annuus L.)

To identify the possible quarantine viruses in seven common sunflower varieties imported from the United States of America and the Netherlands, we tested total RNAs extracted from the leaf tissues using next-generation sequencing of small RNAs. After analysis of small RNA sequencing data, no any quarantine virus was found, but a double-stranded RNA(dsRNA) molecule showing typical genomic features of endornavirus was detected in two varieties, X3939 and SH1108. Full-length sequence and phylogenetic analysis showed that it is a novel endornavirus, temporarily named as Helianthus annuus alphaendornavirus(HaEV). Its full genome corresponds to a 14 662-bp dsRNA segment, including a 21-nt 5′ untranslated region(UTR), 3' UTR ending with the unique sequence CCCCCCCC and lacking a poly(A) tail. An open reading frame(ORF) that encodes a deduced 4 867 amino acids(aa) polyprotein with three domains: RdRP, Hel and UGT(UDP-glycosyltransferase). HaEV mainly distributed in the cytoplasm but less in the nucleus of leaf cells by fluorescence in situ hybridization(FISH) experiment. This virus has a high seed infection rate in the five varieties, X3907, X3939, A231, SH1108 and SR1320. To our knowledge, this is the first report about the virus of the family Endornaviridae in the common sunflower.     

我国北部冬麦区小麦区域试验重复次数和试点数量的优化设计

农作物品种区域试验重复次数和试点数量的合理配置有利于提高试验的成本效率和品种选择效率。本研究分析了2010—2019年期间北部冬麦区小麦品种区域试验的重复次数和试点数量设置的合理性,依据小麦品种试验的信噪比和遗传力水平随重复次数和试点数量的变化规律,提出了重复次数和试点数量的优化设计方案。结果表明:(1)北部冬麦区小麦单点试验的遗传力平均达到0.87,需要的重复次数平均值仅为1.4,说明3次重复可以充分保证试验精确度的需求。(2)北部冬麦区水地组和旱地组小麦区域试验达到0.75的遗传力水平时,需要的试点数量分别为11个和13个,目前有效试点数量分别约为11个和8个,分别达到0.75和0.60的遗传力水平。(3)小麦品种区域试验结果对品种的审定和应用十分重要,而每年都可能有少数试验点因为各种异常情况而报废,为保证试验结果的可靠性,可按H=0.75的水平需求安排试验点数量和重复次数,即重复次数可保持当前的3次;水地组的试点数量可保持在11个左右;旱地组可将试点增加到13个;如要将遗传力提高到0.80的水平,则需约16个试点。     

Intensive hatchery performance of Pacific white shrimp in the biofloc system under three different fertilization levels

Bacterial inorganic nitrogen control using carbon:nitrogen ratio (C:N) manipulation is a tool for aquaculture systems. The present study assessed the hatchery performance of Litopenaeus vannamei between the mysis 1 and postlarvae 5 stages in a zero-exchange biofloc system under different C:N fertilization levels (10:1, 12.5:1 and 15:1) with dextrose. Water quality, performance parameters and water microbiology were compared among treatments. The mean values of the evaluated water quality parameters were appropriate for this production stage. Fertilization with dextrose efficiently controlled ammonia levels, which did not reach the average concentrations considered toxic for the species. In the 10:1 C:N ratio treatment, the levels of ammonia started to increase early and showed significantly higher levels from the third to the last experimental day. There was no difference among groups in means of survival (>76%) and dry weight (0.26 mg) of L. vannamei production parameters and water quality were maintained without water exchange using a biofloc system supplemented with dextrose. Therefore, the use of biofloc systems without water exchange with dextrose as a carbon source in C:N ratios of 10:1, 12.5:1 and 15:1 results in both adequate production indexes and water quality during the misis 1 to post-larvae 5 hatchery phases of L. vannamei. However, the ratios of 12.5:1 and 15:1 keep lower levels of ammonia.     

添加有机硅表面活性剂对低容量喷雾防治小麦蚜虫的影响

室内试验表明,有机硅表面活性剂Silwet408、非离子表面活性剂OP-10和JFC可显著降低药液的表面张力,其中Silwet408在质量分数为0.05%时可使水的表面张力降到22.05 mN/m,表面活性最强。当药液中含有0.001%的有机硅表面活性剂Silwet408时,其在小麦叶片上的接触角即开始显著减小,且在小麦背面的接触角小于在正面的接触角。在10%吡虫啉可湿性粉剂稀释2500倍药液中添加Silwet408,药液的表面张力和其在小麦叶片上的接触角明显降低,雾滴在小麦叶片上扩展面积明显增大。进一步田间试验表明,使用手持离心式低容量喷雾机喷雾,在10%吡虫啉可湿性粉剂药液中添加质量分数为0.05%和0.1%的Silwet408,可显著增加对小麦蚜虫的防治效果。     

Measuring consumer response to ‘Gala’ apples treated with 1-methylcyclopropene (1-MCP)

Post-harvest apple treatment with 1-methylcyclopropene (1-MCP) was previously found to inhibit fruit ripening but also to inhibit the production of volatile compounds that contribute to apple flavor. The first objective of this study was to determine if consumers could distinguish 1-MCP treated and untreated Gala apples [Malus sylvestris L. (Mill.) var. domestica Borkh. Mansf.] following long-term storage. Chemical analysis showed 1-MCP treated fruit had reduced flavor volatiles compared to untreated fruit. Consumer difference tests showed they could distinguish between 1-MCP treated and untreated fruit. A second objective was to compare consumers’ acceptance for 1-MCP treated to untreated apples. Both 1-MCP treated and untreated apples received high overall liking scores that were not significantly different. Equal numbers of consumers indicated preference for 1-MCP treated and untreated fruit and there was no difference in purchase intent. However, subsets of consumers who eat Gala, Fuji or Red Delicious apples showed preference for untreated over 1-MCP treated fruit compared to consumers who do not eat these varieties.     

不同水源磁化处理对生菜光合和矿质元素及产量的影响

【目的】探究不同水源磁化处理对生菜光合特性等生理生化和产量的影响。【方法】在日光温室条件下,以意大利生菜为供试对象,采用随机区组设计,设置2个因素:磁化(M)和灌溉水源(T),磁化设置未磁化处理(M0)和磁化处理(M1)2个水平,灌溉水源设置淡水(T1)、再生水(T2)、微咸水(T3)3个水平,共6个处理。通过盆栽试验研究了3种水源磁化处理对生菜净光合速率、抗氧化酶活性、矿质元素及产量等的影响。【结果】不同水源磁化处理灌溉效果有所差异。生长中期,M1T1、M1T2处理分别较M0T1、M0T2处理的净光合速率显著提高11.16%、14.73%。3种水源磁化处理灌溉的超氧化物歧化酶、过氧化物酶、过氧化氢酶活性显著提高12.77%~23.09%。M1T1、M1T2处理分别较M0T1、M0T2处理的生菜叶片氮质量分数显著提高7.71%、6.83%,生菜产量分别显著提高9.42%、10.15%,但M1T3与M0T3处理的生菜产量无显著差异。不同水源磁化处理的生菜叶片P、Ca、Mg、Na、K质量分数有不同程度的提高,水分利用效率提高5.03%~11.65%。【结论】磁化水灌溉有利于生菜光合等生理生化活动,提高产量和水分利用效率,淡水和再生水磁化效果优于微咸水。     

中国长江流域冬麦区小麦品种试验精确度回溯分析

为全面评价长江流域小麦品种区域试验精确度的发展水平,分析了2011—2021年度中国长江流域冬麦区单年单点和一年多点小麦区域试验的试验精确度和品种比较精确度,对产量、穗数、穗粒数、千粒重、生育期、株高、基本苗和最高茎数等性状的试验精确度差异进行了比较。结果表明,长江流域冬麦区单年单点品种试验精确度较好,试验误差变异系数(CEV)在5%和10%以下的试点数占比分别在60%和95%以上,但品种比较精确度(RLSD_0.05)在3%以下的试验比例不到10%,长江上游和中下游单点品种试验RLSD_0.05在10%以下的试点数分别占比约60%和90%。一年多点区域试验精确度和品种比较精确度显著优于单年单点试验,上游和中下游试验平均CEV分别在8%和5%以下。采用试点固定模型时,长江上游和中下游试验平均RLSD_0.05分别为2.19%和1.49%,符合国家小麦品种审定标准对品种比较精确度的要求;但采用试点随机模型时,小麦品种试验尚无法鉴别出品种间3%的产量差异。试验对生育期、株高、基本苗、千粒重和穗数的RLSD_0.05优于产量性状,而最高茎数和穗粒数的RLSD_0.05较低。     

政府购买服务承接能力建设问题研究——以部属公益二类事业单位为例

政府购买服务是我国公共服务供给的一种模式创新,对经济社会高质量发展具有重要意义。党的十八大以来,部属公益二类事业单位作为政府购买服务新的重要的承接主体,在实践中服务能力与服务质量不断得到提升,但由于历经时间不长,部属公益二类事业单位的承接能力与政府购买服务的要求还不完全相适应,还存在着一些需要研究解决的矛盾。文章对承接能力的概念、内涵和基本特征进行了创新性分析界定,在此基础上,结合当前部属公益二类事业单位政府购买服务承接能力的现状与问题,提出了加强承接主体能力建设的思路与对策。     

Field evolution of insecticide resistance in the brown planthopper (Nilaparvata lugens Stål) in China

The brown planthopper (Nilaparvata lugens Stål) is one of the most destructive pests of rice crops in Asian countries including China, Vietnam, Thailand, etc. Evolution of resistance in this pest insect to isoprocarb, buprofezin, pymetrozine, imidacloprid and other neonicotinoid insecticides has been reported. In order to investigate the current status of resistance to commonly used insecticides, nine field populations of N. lugens were collected from Central China, East China and South China, and resistance to insecticides was monitored from 2009 to 2012. All the 9 field populations collected in 2012 had developed extremely high resistance to imidacloprid, with resistance ratios (RR) ranging from 209.3 to 616.6. Resistance to imidacloprid was much higher in 2012 than in 2009. The RR of thiamethoxam varied from 17.4 to 47.1, and the RR of nitenpyram varied from 1.4 to 3.7 in 2012. Of the 9 field populations, six populations showed higher resistance to nitenpyram in 2012 than in 2011. RR for buprofezin varied from 110.1 to 221.6 in 2012 whereas resistance was at a medium level (RR 20.4 ∼ 39.4-fold) in 2009. RR for pymetrozine ranged from 34.9 to 46.8 in 2012. As for isoprocarb, RR ranged from 21.7 to 38.1 in 2012. The obvious increase in resistance to widely applied insecticides indicates that insecticide resistance management strategies are urgently needed to prevent or delay further increase of insecticide resistance in N. lugens.