景谷蔗区春植甘蔗高产优化模式栽培技术研究

在抗旱技术下，对甘蔗下种量，行距，施肥量采用二次通用旋转组合设计进行试验，建立产量函数模型，试验表明各因子对产量有显著作用，影响顺序是氮〉下种量〉钾〉磷〉行距，下种量和种植行距，施氮水平和下种量，施氮与施磷，施磷与施钾等交互作用达到了显著或极显著水平，应用产量回归数学模型，结合蔗区自然条件和耕作水平，制定约束水平，通过模拟运筹，制定出旱地蔗区的高产优化模式技术方案。     

滇西秋植甘蔗高产综合模式技术开发研究

在云南旱地上,改传统春植为秋植,在秋植规范栽培技术下,对秋植甘蔗下种量、行距、施氮、施磷、施钾五个重要因素采用二次通用旋转组合设计试验。建立秋植甘蔗栽培数学模型,根据试验示范蔗区不同生产条件,筛选出公顷单产８２．５～９０ｔ、９０～９７．５ｔ、９７．５～１０５ｔ三个产量层次的模式技术供生产示范推广。     

甘蔗新品种粤糖00-236配套栽培技术研究

本研究采用正交试验探讨合理的氮、磷、钾施用量和播种量.在地膜覆盖和土壤水分适宜的条件下,以水平组合处理7(尿素600 kg/hm2、普钙2250 kg/hm2、氯化钾450 kg/hm2、下种量45000双芽/hm2)和处理1(尿素1050 kg/hm2、普钙2250 kg/hm2、氯化钾600 kg/hm2、下种量45000双芽/hm2)栽培粤糖00-2 36品种最优,达到显著增产、增糖、增收的效果.增施(1 500 kg/hm2增至2250 kg/hm2)磷肥,有极显著的增产增糖效果,对植株生长高度亦有显著的提高.下种量的增加(37500双芽/hm2增至45000双芽/hm2)蔗茎产量和有效茎数有显著的增加,并对植株生长高度有增加和对蔗茎粗度有影响减小的趋势.增施尿素(600 kg/hm2增至1050 kg/hm2)和增施钾(450 kg/hm2增至600 kg/hm2)肥,未见有明显的影响.     

粤糖00-236和ROC10适宜植期、下种量与施肥量研究

在湛江蔗区,对甘蔗新品种粤糖00-236和当地主栽培品种ROC10进行不同植期、不同下种量及不同施肥水平的试验.结果表明,提早植期和增施磷肥有显著的增产增糖效果.粤糖00-236的平均蔗茎产量与ROC10相近,但其公顷含糖量极显著高于后者.粤糖00-236特早熟高糖,适合糖厂早期开榨.在本试验条件下,公顷下种量45000段与37500段双芽苗之间、公顷尿素施用量1050kg与750kg之间,以及公顷氯化钾施用量600kg与450kg,蔗茎产量和含糖量均无显著差异.     

翁源蔗区甘蔗施肥量、斩种方式和下种量试验

采用正交试验探讨合理的氮、磷,钾施用量、下种量和不同斩种方式。在地膜覆盖和土壤水分适宜的条件下,双芽苗的萌芽率显著优于半茎苗。本试验条件下,在施1500kg／hm^2过磷酸钙的基础上,增施磷肥有显著的增产效果。在施750kg／hm^2尿素和450kg／hm^2氯化钾的基础上,增施氮和钾虽有增产趋势,但未达显著水平。本试验甘蔗生长中后期遭受严重干旱,可能较大程度上影响到追施的氮肥和钾肥的肥效。     

镇康旱地甘蔗高产优化栽培技术研究

采用五元二次正交通用旋转设计，研究了甘蔗下种量、行距、氮、磷、钾肥用量与产量的关系。结果表明：下种量、行距、氮肥、磷肥、钾肥对产量的作用顺序是：下种量＞氮肥＞行距＞钾肥＞磷肥。通过计算机模拟分析、寻优；提出了公顷产量在５７～７５ｔ之间的优化栽培方案，为镇康旱地甘蔗高产优化栽培提供了科学依据。镇康旱地甘蔗高产优化栽培技术研究@刘少春     

栽培因素对烤烟经济性状的效应分析

利用正交设计与统计分析研究了栽培因素对烤烟经济性状的效应,结果表明在一定范围内,施氮量对烤烟产量的影响是主要因素,留叶数是次重要因素,种植密度是次要因素,其中施氮量效应大于留叶数效应;施氮量对烤烟产值的影响是主要因素,种植密度是次重要因素,留叶数是次要因素,其中施氮量效应大于密度效应.     

东北烟区低焦油烟叶关键栽培技术研究

东北烟区作为我国最大的填充型低焦油烟叶产区,研究其低焦油烟叶关键生产技术具有重要意义。在辽宁、吉林通过施氮量、施钾量、留叶数和株距4因素二次回归正交组合试验,研究其对烤烟焦油释放量及内在理化指标的影响。在施氮量、施钾量、留叶数和株距4个处理的单因素效应中,对焦油释放量的影响均表现为株距留叶数施氮量≈施钾量,焦油释放量稳定最低较理想的处理组合为(1)辽宁宽甸点:施氮量4.50 kg/667m~2、施钾量20.08 kg/667m~2、留叶15片,株距0.40m。(2)吉林汪清点:施氮量3.99 kg/667m~2、施钾量18.10 kg/667m~2、留叶20片,株距0.33 m。与当前生产对照比较,较理想的处理组合为施氮量均降低0.5 kg/667m~2,钾氮比均上调0.5,留叶均增加2片,株距减少0.15 m左右。在辽宁宽甸点,施氮量对总植物碱的影响最大,施钾量和留叶数对K_2O的影响最大。在吉林汪清点,株距对叶宽的影响最大。东北低焦油烟叶生产应以群体质量控制为主,其次是养分运筹调控。辽宁低碱高钾、吉林较低的叶宽可作为东北低焦油烟叶的理化特征参考指标,建议在东北烟区进一步对优选组合技术验证后推广,并深入研究低焦油烟叶形成的生理机制。     

施氮量与留叶数对烤烟产量影响的研究

采用二次饲和Ｄ－最优设计。试验研究了施氮量与留叶数对烤烟产量、效益有烟叶化学成分含量的影响。结果表明：亩施氮量３．５０～５．７３ｋｇ、单株留叶数１６～１８片，烟叶亩产量可达１５０～２００ｋｇ，亩产值４００元以上。烟碱含量２．５％～３．０％，还原糖量１５％～１７％。主因素效应以施氮量对产量、产值、还原糖的影响最大，留叶数次之，二因素对烟碱的主效应大小相近。     

施氮量与留叶数对烤烟产量质量影响的研究

采用二次饱和 D—最优设计,试验研究了施氮量与留叶数对烤烟产量、效益及烟叶化学成分含量的影响。结果表明:亩施氮量3.50～5.73kg、单株留叶数16～18片,烟叶亩产量可达150～200kg,亩产值400元以上,烟碱含量2.5%～3.0%,还原糖含量15%～17%。主因素效应以施氮量对产量、产值、还原糖的影响最大,留叶数次之,二因素对烟碱的主效应大小相近。     

Effect of Cultivation Conditions on Retrogradation of Sweetpotato Starch

Sweetpotatoes were grown under four cultivation conditions, i. e. early planting and early harvesting (I, E‐E), standard (II, STD), early planting and late harvesting (III, E‐L), and late planting and late harvesting (IV, L‐L). Retrogradation of the starch isolated from fresh roots was estimated by the hardness and syneresis rate after two weeks of storage at 5 °C. A significant difference in retrogradation among the cultivation conditions and cultivars was observed. The starch tended to exhibit slower retrogradation in late harvesting, where the temperature was low. The differences in amylose content and the proportion of short unit‐chains (DP 9‐11) of amylopectin among cultivation conditions were also significant. Starch retrogradation was positively correlated with the proportion of chains with DP 12‐14 but negatively correlated with the proportion of DP 9‐11. Moreover, there was no significant correlation between amylose content and retrogradation. These results indicate that the main factor for retrogradation under any cultivation condition is the proportion of short unit‐chains of amylopectin. The best performance of sweetpotato starch as a food ingredient would be achieved by selecting both the proper cultivar and cultivation conditions.     

Occurrence and genotypes of Campylobacter in broiler flocks, other farm animals, and the environment during several rearing periods on selected poultry farms

On 15 Swiss poultry farms, broiler flocks, other farm animals, and the environment were examined during consecutive rearing periods to investigate the occurrence and genetic diversity of Campylobacter. Of the 5154 collected samples, 311 (6%) from 14 farms were Campylobacter positive by culture. Amongst the positive samples, 228 tested positive for Campylobacter jejuni and 92 for Campylobacter coli. Positive samples originated from broilers, the broiler houses, cattle, pigs, bantams, laying hens, a horse, and a mouse. Feed, litter, flies, and the supply air to the broiler house tested negative. By flagellin gene typing (fla-RFLP) and pulsed-field gel electrophoresis (PFGE), 917 Campylobacter isolates were genotyped. Additionally, amplified fragment length polymorphism (AFLP) analysis was performed on 15 assorted strains. On eight farms, matching genotypes were isolated from broiler flocks and other farm animals: Certain genotypes from cattle (farms H, K, L, and M), pigs (farms D and P), or laying hens (farm L) were subsequently found in the broiler flocks, whereas other genotypes initially present in the broiler flocks turned up in cattle (farms A, D, and O). These results emphasize the importance of other farm animals on poultry farms for broiler flock colonization. Indications of persistent contamination of the broiler house were evident on four farms (C, D, I, and L) where matching genotypes were detected in consecutive broiler flocks, but not concurrently in other samples. By fla-RFLP, PFGE, and confirmed by AFLP, some genotypes proofed to be identical across different farms.     

不同烤烟种植模式的物质流、能量流及价值流分析

确定合理的种植模式对提高烟田生态系统的生产效率,促进烟草农业的可持续发展十分重要。以皖南地区4种典型烤烟种植模式为研究对象,采取田间调查分析的方法,从农田生态系统的物质流、能量流和价值流角度研究了不同烤烟种植模式的氮磷钾投入产出、投能结构和价值转换及其数量特征。研究结果表明,各烤烟种植模式均需调控氮、磷肥的施用量及其肥料结构,提高其利用率,并在各烤烟轮作模式中重视钾肥施用及秸秆还田管理。在各作物中种植烤烟的有机能和无机能之比最高(0.71),且其投能组成中人力能最高,其次是化肥能及农机能。烟稻复种连作的T1模式其能量产投比最低,而烤烟轮作的T2模式最高。虽然T1模式的经济纯收入最高,但从价值产投比和物质及能量的高效利用角度综合考虑,烤烟-水稻→小麦-水稻→烤烟的2年轮作种植模式为皖南地区较优的烤烟种植模式,后续可进一步推广应用。     

Genetic diversity and molecular epidemiology of outbreaks of Klebsiella pneumoniae mastitis on two large Chinese dairy farms

Klebsiella pneumoniae is an opportunistic and environmental mastitis-causing pathogen, with potential for contagious transmission. Repetitive element sequence-based PCR was used to determine genetic diversity and explore potential transmission and reservoirs for mastitis caused by K. pneumoniae on 2 large Chinese dairy farms. A total of 1,354 samples was collected from the 2 dairy farms, including milk samples from cows with subclinical and clinical mastitis, bedding, feces, feed, teat skin, and milking liners. Environmental samples were collected from all barns and milking parlors and extramammary samples from randomly selected dairy cows on both farms. In total, 272 and 93 K. pneumoniae isolates were obtained from Farms A and B, respectively (with ~8K and 2K lactating cows, respectively). Isolation rates from clinical mastitis (CM), subclinical mastitis (SCM), and environmental or extramammary samples were 34, 23 and 37%, respectively for Farm A and 42, 3, and 34% for Farm B. The K. pneumoniae isolated from CM milk and extramammary or environmental sources had high genetic diversity (index of diversity >90%) on the 2 farms and from SCM on Farm A. However, on Farm B, 9 SCM isolates were classified as 2 genotypes, resulting in a relatively low index of diversity (Simpson's index of diversity = 0.39; 95% CI = 0.08–0.70). Genotypes of K. pneumoniae causing mastitis were commonly detected in feces, bedding, and milking liners (Farm A), or from teat skin, sawdust bedding, and feed (Farm B). Based on its high level of genetic diversity, we inferred K. pneumoniae was an opportunistic and environmental pathogen causing outbreaks of CM on these 2 large Chinese dairy farms. Nevertheless, that only a few genotypes caused SCM implied some strains had increased udder adaptability and a contagious nature or a common extramammary source. Finally, control of intramammary infections caused by K. pneumoniae on large Chinese dairy farms must consider farm-level predictors, as the 2 outbreaks had distinct potential environmental sources of infection.     

Potassium nutrition of the strawberry plant. Effect of potassium treatment and of the rooting media on components of yield and critical leaf potassium concentrations

Strawberry plants, cv. Cambridge Favourite were grown (a) with 5 different levels of potassium from planting to dormancy, followed by a constant level of K in the flowering and fruiting phase; or (b) with a constant level of K from planting to dormancy, followed by 4 different levels of K during the flowering and fruiting phase. The experiment was carried out in 3 different rooting media—sand, peat and rock wool. Application of K ranging from 0.125 to 2 mEq/litre in the nutrient solution over the period from planting to dormancy had no significant effect on any of the components of yield subsequently measured. Application of K ranging from 0.25 to 2 mEq/litre over the flowering and fruiting period produced significant effects on yield, mainly because of increased flower production. Yields for different rooting media, and even between plants grown in the same medium, varied considerably due to factors other than potassium nutrition, but the leaf potassium concentration at the fruit ripening stage associated with maximum yield of fruit (>7 g per berry) was constant at about 1.2% K, irrespective of the actual yield.     

基于电感耦合等离子体质谱仪分析矿物元素含量的大豆产地溯源

为表征相似地域特性的溯源指标,提高矿物元素对大豆产地溯源的准确性及稳定性。采用电感耦合等离子体质谱仪分析黑龙江省北安市9个农场及黑河市嫩江县6个农场共42个大豆样品中矿物元素含量,对所得的矿物元素含量数据进行方差分析、主成分分析和判别分析。结果显示:北安市和黑河市嫩江县矿物元素溯源指标,第1主成分主要由V、Fe、La、Ce、Pr、Nd、Dy、Er、Yb 9种元素构成,贡献率最大,为28.390%;第2主成分主要由As、Se、Lu、Ir、Au 5种元素构成,贡献率为14.435%;第3主成分主要由Ca、Ni、Cd、Ba 4种元素构成,贡献率为10.881%。利用大豆中矿物元素含量的分析,实现了省内大豆主产区产地溯源,并获得了黑龙江省两个大豆主产区溯源指标,分别为Na、K、Mn、Rb、Ba和Au 6种元素。综合2个主产区42个大豆样品矿物元素分析结果,实现了对黑龙江省两大主产区大豆产地溯源的准确判别,正确判别率为100%。     

Tetracycline resistance genes persist at aquaculture farms in the absence of selection pressure

The prophylactic and therapeutic use of tetracyclines in aquaculture has been shown to contribute to the spread of tetracycline resistance in the environment. In this work, the prevalence of four different tetracycline-resistance genes, tetA, tetC, tetH, and tetM, in sediments from four aquaculture farms and their surroundings in the Baltic Sea was monitored by quantitative polymerase chain reaction (qPCR). The presence of three additional tetracycline-resistance genes (tetE, tetG, and tetW) was studied qualitatively by standard PCR, and the amount of bioavailable tetracyclines and total amounts of tetracycline and oxytetracycline in samples were also measured. None of the farms were using tetracycline at the time of the sampling and one of the farms had stopped all antibiotic use six years prior to the first sampling. Two of the farms were sampled over four successive summers and two were sampled once. Our results showed greater copy numbers of tetA, tetC, tetH, and tetM at the farms compared to pristine sites and demonstrated the presence of tetE, tetG, and tetW genes in the sediments under aquaculture farms at most sampling times. However, no resistance genes were found in samples collected 200 m from any of the farms. None of the samples contained therapeutically active concentrations of tetracyclines at any of the sampling times, suggesting that the increase in the prevalence of tetracycline resistance genes is caused by the persistence of these genes in the absence of selection pressure.     

Distribution of Campylobacter spp. in selected U.S. poultry production and processing operations.

A study was conducted of 32 broiler flocks on eight different farms, belonging to four major U.S. producers. The farms were studied over I complete calendar year. Overall, 28 (87.5%) of the flocks became Campylobacter positive, and only four (12.5%) remained negative throughout the 6- to 8-week rearing period. In the majority of flocks, sampled every 2 weeks throughout production, Campylobacter-positive fecal and cecal samples were not detected until 4 to 8 weeks of age. In only six of the flocks were environmental samples found to be positive before shedding of Campylobacter was detected in the birds. Even in some of the Campylobacter-negative flocks, contamination of the rearing environment was positive for Campylobacter but did not result in the birds subsequently excreting the organism. These findings are discussed in relation to U.S. husbandry practices and present uncertainty about sources of Campylobacter infection for poultry flocks. Birds were often transported to the processing plant in coops that were already contaminated with Campylobacter, and the organisms were sometimes found in samples of scald water and chill water. After chilling, the proportions of Campylobacter-positive carcasses from different producers ranged from 21.0 to 40.9%, which is lower than in other studies, and possible reasons are considered.     

南平烟区植烟土壤理化性状聚类分析与施肥对策

为了加强烤烟平衡施肥的分类指导和制定烤烟专用肥配方提供依据,根据烤烟种植面积分布,采集了南平烟区植烟土壤样品1101份,测定了主要理化性状,并运用聚类分析进行综合评价。结果表明,南平烟区植烟土壤偏酸,质地主要为壤土,交换性镁、有效铁、有效锰、有效铜含量丰富,有机质、全氮、全磷、速效磷、有效硫、有效锌含量中等,碱解氮、速效钾、交换性钙、水溶性氯含量较低,全钾、有效硼含量低。土壤pH变异最小,变异系数为7.71%;速效磷、水溶性氯和有效硼变异较大,变异系数分别达到80.30%、77.90%和75.87%。南平烟区植烟土壤可分成5个类群,各类群土壤均应施用氧化钙或与氧化镁交替施用调节pH。烤烟施肥上,第Ⅰ类群土壤应“控氮增钾,适磷补硼”,第Ⅱ类群土壤应“适氮增钾,补磷控硫”,第Ⅲ类群土壤应“适氮磷,重施钾,补硼氯”,第Ⅳ类群土壤应“适氮增钾,控磷硫,补硼氯”,第Ⅴ类群土壤应“适氮控磷增钾,补硼氯”。     

密度和施氮量互作对烤烟叶片组织结构的影响

为探究种植密度和施氮量对烤烟中部叶片组织结构的影响,以烤烟品种NC102为材料,采用裂区设计,以种植密度为主区,施氮量为副区,在大田条件下分别采集10、20、40和73 d叶龄的中部叶片,制作石蜡切片并观察组织结构。结果表明,叶片厚度、栅栏组织厚度、海绵组织厚度、叶面积随叶龄增加均增加,栅栏细胞密度反之。随种植密度的降低和施氮量的提高,叶片厚度、栅栏组织厚度、海绵组织厚度、叶面积、比叶重均增加,栅栏组织密度降低。施氮量对栅栏细胞密度的影响早于种植密度,对栅栏组织厚度的影响晚于种植密度。73 d时叶片厚度、栅栏组织厚度、组织比、叶面积、比叶重受低种植密度和高施氮量的正交互作用影响,密度越低,施氮量增加对叶片组织结构的影响更加显著。在一定范围内,适当调节种植密度和施氮量,利用其交互作用,可以改善叶片结构,达到优质适产的目的。