巴西橡胶树抗白粉病室内鉴定模型的建立

选取20份巴西橡胶树品系,将白粉病菌纯化后进行大田鉴定和3种温度下的室内鉴定,以评价各品系对白粉病的抗性并建立橡胶树抗白粉病室内鉴定模型。结果表明,20个橡胶树品系人工接种大田鉴定结果为高抗品系6个,抗病品系5个,感病品系3个,高感品系6个。在设置的22、25、28℃3个培养温度条件下,白粉病菌菌丝长度存在极显著差异,培养温度越高,病菌菌丝生长速度越快,菌丝长度越长。同时发现3种温度下白粉病菌菌丝长度比值不存在差异性,具有极其良好的稳定性。建立病情指数(y)与菌丝长度比值(x)的回归方程为:y=-62.072+80.909 54x,该方程可用于预测巴西橡胶树品系对白粉病的抗性等级。同时对橡胶树白粉病室内抗性评价的分级进行了修改,结合回归方程建立了巴西橡胶树抗白粉病室内鉴定模型,旨在为完善高效的巴西橡胶树抗白粉病鉴定评价体系提供基础和技术支持。     

半干旱地区马铃薯覆膜方式的研究

在大田条件下,以不同的种植方式和覆膜时期为处理,研究半干旱区不同种植模式对马铃薯产量和经济效益的影响。结果表明:采用全膜双垄沟播技术种植马铃薯使得产量和经济效益较其他种植模式分别提高9.0%~46.8%和9.20%~59.62%。     

南方坡耕地种植苎麻水土保持机理研究

为了明确苎麻水土保持机理,进而为大面积利用苎麻治理坡耕地水土流失提供理论依据,对苎麻不同利用方式叶面积指数、茎叶截留效应、枯落物持水能力、地下根系分布进行了研究。结果表明：不收获小区苎麻叶面积指数明显大于对照;苎麻不收获小区茎叶截留量最大为2.56 mm,高于其他小区;最大枯落物持水量,不收获小区最大为2.4 mm,饲用小区最小为0 mm;种植苎麻小区不同类型根系鲜重为萝卜根>扁担根>龙头根>细根;苎麻根系深度可达60 cm,玉米根系深度只有30 cm。研究表明,苎麻水土保持效果好,主要是其根系入土深、主根发达、根系分布广、覆盖时间长、叶面积指数大。     

灌区尺度氮磷的迁移转化特征分析

为了解中国土壤中残留农业面源污染物的迁移转化规律及其特征,以前郭灌区典型灌域为研究对象,通过10组试验处理与小区田间试验,在不同深度提取水样,进行水质观测和数据处理,主要对铵氮、硝氮以及磷酸盐在土壤剖面上的迁移转化规律展开分析研究。结果表明,各试验小区表层水的氨氮浓度在施肥后的一段时间内有一个峰值出现,并随后呈现衰减趋势,在灌水量和施肥量越大的情况下,随水向下迁移的铵氮量越大（灌水量NI处理比SI处理多2.2 kg/hm2,施肥量NF处理比SF处理多1.5 kg/hm2）,在施肥越均匀的情况下,随水向下迁移的铵氮量越小（F1处理比F2处理少0.7 kg/hm2）;各试验小区表层水的硝氮浓度具有与铵氮相似的变化趋势,在灌水量越大、施肥量越大及施肥越不均匀的情况下,进入地下水的硝氮量皆越大（灌水量NI处理比SI处理多1.12 kg/hm2,施肥量NF处理比SF处理多0.55 kg/hm2,施肥比例F1处理比F2处理多0.4 kg/hm2）,对地下水造成的污染也越大;各试验小区表层水的磷酸盐浓度在第一次施肥（底肥）呈现一个极大的峰值,然后迅速回落并持续稳定在一个较小的水平内（不超过2.5 mg/L）。     

Genome‐wide identification of pathogenicity genes in Xanthomonas oryzae pv. oryzae by transposon mutagenesis

A transposon mutant library was constructed from the bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo) KACC10331 by Tn5 transposon mutagenesis. The susceptible rice cultivar Milyang 23 was inoculated with a total of 24 540 mutants resistant to kanamycin and 67 avirulent or reduced‐pathogenicity mutant strains were selected for study. Southern hybridization verified that 84 mutant strains had single‐copy insertions and their single‐transposon insertion sites were identified by sequencing analysis combined with thermal asymmetric interlaced (TAIL)‐PCR. The single‐transposon‐tagged sequences of 21 mutant strains belonged to pathogenicity‐related genes previously reported in Xanthomonas species, while the other 46 single‐transposon‐tagged sequences included diverse functional genes encoding, five cell‐wall‐degrading enzymes, three fimbrial and flagella assembly regulators, five regulatory proteins, 15 metabolic regulators and 18 hypothetical proteins, which were identified as novel pathogenicity genes of Xoo.     

Effects of low environmental salinity on the cellular profiles and expression of Na+, K+-ATPase and Na+, K+, 2Cl? cotransporter 1 of branchial mitochondrion-rich cells in the juvenile marine fish Monodactylus argenteus

The goal of this study was to determine the osmoregulatory ability of a juvenile marine fish, silver moony (Monodactylus argenteus), for the purpose of developing a new experimental species for ecophysiological research. In this study, M. argenteus was acclimated to freshwater (FW), brackish water (BW), or seawater (SW). The salinity tolerance of this euryhaline species was effective, and the fish survived well upon osmotic challenges. The largest apical surface of mitochondrion-rich cells was found in the FW individuals. Immunohistochemical staining revealed that Na(+), K(+)-ATPase immunoreactive (NKA-IR) cells were distributed in the interlamellar region of the gill filaments of the silver moony in all experimental groups. In addition to the filaments, NKA-IR cells were also found in the lamellae of the FW individuals. The number of NKA-IR cells in the gills of the FW individuals exceeded that of the BW and SW individuals. The NKA-IR cells of FW and SW individuals exhibited bigger size than that of BW fish. The NKA activities and protein expression of the NKA α-subunit in the gills of the FW individuals were significantly higher than in the BW and SW groups. Additionally, the relative amounts of Na(+), K(+), 2Cl(-) cotransporter 1 (NKCC1) were salinity-dependent in the gills. Immunofluorescent signals of NKCC1 were localized to the basolateral membrane of NKA-IR cells in all groups. In the gills of the FW individuals, however, some NKA-IR cells did not exhibit a basolateral NKCC1 signal. In conclusion, the present study illustrated the osmoregulatory mechanisms of this easy- and economic-to-rear marine teleost with euryhaline capacity and proved the silver moony to be a good experimental animal.     

A dead-end filtration method to remove particle-associated pathogens in aquaculture systems

To reduce the incidence of bacterial diseases in recirculating aquaculture systems, 27 marine bacterial species were introduced into Instant Ocean maintained at 25°C. Those species were enumerated before and after filtration to evaluate the efficiency of the filtration procedure. The effects of sari filter and nylon filter on the survival of sea bass challenged with Vibrio alginolyticus were also determined. The results of laboratory studies indicated that the ability to remove pathogens was typically 1–3 log orders. Above 90% Vibrio sp., i.e., which were attached to particles, were removed by either 20-μm nylon net or four layers of sari. A 9.53% mortality of sea bass was reported in pilot filtration test using sari material as an end filter, while this percentage increased to 33.35% in control groups. It is concluded that a simple filtration procedure that involves the use of four-layer sari material can reduce the numbers of pathogens attached to particles in aquaculture system. The results of this study provide the basis for pathogen reductions in full-scale facilities.     

低温胁迫对扁桃休眠枝条电解质渗出率的影响

[目的]研究低温胁迫对扁桃休眠枝条冻害的影响,比较不同品种的抗寒性.[方法]以新疆4个主栽扁桃品种为材料,通过人工低温处理休眠枝条,测定枝条组织电解质渗出率.[结果]各温度处理区间不同时间处理后电解质渗出率的平均值总体趋势是由低至高;在持续时间上进行比较,12 h达到了极显著水平;4个品种之间比较,双果和小软壳均达到了极显著水平.[结论]在相同低温不同持续时间的处理下,随着低温时间持续,电解质渗出率整体表现为随着时间的延长逐渐升高然后降低的趋势;在不同低温及不同持续时间处理下,被测试的4个品种随着温度的降低,扁桃休眠枝条对低温所能忍受的持续时间则会缩短;4个品种抗寒力强弱的顺序为:双果、纸皮、寒丰、小软壳.     

晋南盆地夏播玉米种植密度对产量及其相关性状变异系数的影响

为确定‘郑单958’玉米品种在晋南盆地夏播的合理种植密度,充分发挥该品种的增产效能,在山西临汾采用随机区组设计方法研究了种植密度对产量及其相关性状变异系数的影响。结果表明:在降雨正常年份,籽粒产量、千粒重、穗长、穗粗和单穗重在不同种植密度间存在差异,而出粒率、穗行数和收获指数不存在差异;种植密度对相关性状的变异系数影响序列为单穗重>籽粒产量>千粒重>穗长>穗粗>穗行数>出粒率>收获指数;穗长、穗粗和穗轴重对单穗重(籽粒)的贡献大小为:穗长>穗粗>穗轴重。晋南盆地夏播玉米增加种植密度可显著提高籽粒产量,其籽粒产量是随干物质积累的增加而协同提高,对收获指数性状影响较小。该项研究为晋南盆地夏播玉米增加种植密度提供了理论和技术支撑。