2014年浑善达克沙地黄柳生长季水分来源同位素示踪研究

黄柳是我国内蒙古东部和辽宁西部沙丘上广泛分布的多年生灌木,是极佳的固沙树种.通过利用氢同位素示踪方法,测定了2014年浑善达克沙地黄柳生长季茎干水与潜在水源(降水、土壤水、地下水)氢同位素比率δD值,并利用多源线性混合模型IsoSource,计算了黄柳对各潜在水源的利用比例.结果表明:在5月黄柳80％以上利用120 ～ 160 cm土壤水和地下水;6月主要吸收0～40 cm土壤水;7月主要吸收120～160 cm土壤水;8月以地下水为主要水源,利用率为82％.这表明生长在不同季节的黄柳对于各潜在水源的利用有特定的适应结果,同时也说明荒漠灌木可以通过自身的调节朝着最优的方向发展,实现最大限度的水分利用.     

农田灌溉模式下塔里木河流域地下水水位的变化分析──以塔里木河上游为例

根据1997、2000年的监测资料,分析了塔里木河上游地下水水位的时空变化,反映了不同的土地利用方式对地下水水位的影响。在农田灌溉模式下,在垂直河道方向上地下水水位的变化受到塔里木河干流水位、农田灌溉和潜水蒸发的影响。沿河道的横切方向上地下水位的变化与距河道距离成正相关,但具有明显的滞后反应,其滞后时间随垂直河道的距离增加而增加。干流水位明显影响地下水的范围为3.5km。农田灌水使地下水水位在3、11月份明显抬升,也在7月份时对地下水水位产生影响,使其抬升。潜水蒸发量随地下水水位的升高而增加,使地下水水位变化趋于缓和。     

连作障碍发生机制研究进展

目的研究不同前作对土壤生物化学性质的影响。方法利用化学和酶学分析及16S多样性测序技术,分析种植7年的不同前作[荞麦(FB)、油菜(FR)、小麦(FW)和绿肥(FG)]烟田土壤的养分、酶活性及细菌群落结构组成。结果(1) FR烟田土壤的有机质、全氮、碱解氮和有效磷含量最高,分别为30.04 g/kg、1.62 g/kg、143.50 mg/kg和88.09 mg/kg,FG烟田次之,但FG烟田速效钾的含量最高(240.10 mg/kg);FG烟田土壤蛋白酶和磷酸酶的活性最高,分别为709.02 μg/(g·d)(酪氨酸)和306.60 μg/(g·h)(对硝基酚),而其脲酶和蔗糖酶的活性仅低于FW烟田,且无显著性差异(P>0.05)。(2)在细菌群落组成上,FB、FG、FW和FR烟田分别检测出770、670、654和597属,归属于Actinobacteria、Proteobacteria、Chloroflexi和Acidobacteria等36门,其中Actionbacteria和Proteobacteria相对丰度最高,分别为26.87%~45.21%和25.82%~30.69%,Treptomyces、Bradyrhizobium、Bacillus和Mycobacterium等拮抗菌和Bradyrhizobium、Rhizobium和Paenibacillus等固氮菌在FB烟田土壤细菌群落的相对丰度最高。结论不同前作对烟田土壤理化性质、酶活性和细菌群落结构的影响不同,绿肥提高了土壤有机质和养分含量以及酶活性;而荞麦改善和提高了烟田土壤细菌种群结构和多样性。     

玉米根系分泌物对烟草黑胫病菌的抑制活性及其抑菌物质分析

目的明确玉米、辣椒单作和间作种植后根围土壤细菌群落的变化与病害发生的关系,解析土壤微生物在玉米和辣椒多样性种植中控制病害的作用。方法比较玉米/辣椒间作和分别单作后根围土壤微生物对玉米小斑病和辣椒疫病发生的影响,并应用Illumina Miseq高通量测序技术比较不同处理根围细菌群落的差异。结果单作玉米的根围土壤微生物能显著抑制辣椒疫病的发生(P<0.05),辣椒单作、玉米/辣椒间作后玉米根围土壤微生物降低玉米小斑病的趋势明显。根围土壤细菌群落分析结果表明：单作玉米根围气单胞菌属、堆囊菌属和固氮螺菌属等的相对丰度显著高于间作玉米和单作辣椒根围(P<0.05);单作辣椒和间作玉米根围土壤中拟杆菌门相对丰度上调,并且其中的拟杆菌属、农研丝杆菌属、鞘氨醇杆菌属和Muribaculum的相对丰度也显著上调(P<0.05)。结论玉米/辣椒间作和间作后有利于帮助彼此降低病害的发生。单作或间作后导致土壤细菌群落的变化是其缓解病害发生的重要机制。     

基于LF-NMR及MRI 的2种速生材干燥过程中水分分布状态研究

为了解太阳能干燥过程中速生材内部水分状态及迁移规律,采用低场核磁共振及核磁共振成像检测桉、杨木干燥过程中水分分布、含量变化及迁移过程,借助扫描电镜在微观层面进行分析。结果表明：核磁共振信号强度与称重法所测含水率相关性系数高达0.99以上,因此低场核磁共振可准确测定木材中的水分含量;桉木和杨木饱水试样的核磁共振信号中均存在3种峰,桉木弛豫时间分别为1.32、32.75、403.70 ms,杨木为2.66、32.75、352.12 ms,对应着结合水及两种状态的自由水;随着干燥进行,不同状态水分的横向弛豫时间逐渐减小,木材对水分的束缚增加。当桉木含水率为27.28%,杨木含水率为35.71%左右时,水分散失转为以结合水为主。通过核磁共振成像中氢质子密度的不同可对水分含量进行区分,进而可观测干燥过程中木材内部水分移动状态。因此,通过低场核磁共振及核磁共振成像可研究速生材干燥过程中的内部水分状态及分布。     

用虚拟水理论探讨干旱区生态用水问题

新疆有限的水资源不可避免地导致绿洲农业经济用水与生态用水的矛盾.虚拟水理论是有别于传统水资源配置的一个新理论.通过分析目前新疆绿洲农业生产用水与生态用水的现状,计算出新疆主要农作物的虚拟水含量,尝试用虚拟水策略探讨干旱区水资源的合理利用,并分析该理论在新疆水资源利用方面的前景,以及存在的一些问题.     

土壤处理对西洋参根际线虫数量动态的影响及对防治茎线虫根腐病的效果

 Root rot of American ginseng (Panax quinquefolium) caused by Ditylenchus destructor is a novel disease found recently in Beijing area. The effects of three soil treatments (fumigating with chloropicrin, chloropicrin + lvfeng organic manure and nematicide fosthiazate) on the number of rhizospheric nematodes, survived plants, root yield and root rot of 3-year ginseng plant were compared. The effects were also investigated at the second year after treatment. The results indicated that the number of parasitic nematodes in rhizosphere of treated soil reached the peak value in late June to early July as the soil temperature raised in the growing season. Compared with the regular treatment, the number of plant parasitic nematodes was reduced while non-plant parasitic nematodes increased. The number of non-plant parasitic nematodes in the soil treated with chloropicrin + lvfeng organic manure was 2 times than that treated with chloropicrin only. The ratio of non-parasitic to parasitic nematodes of three treatments was higher than the control. Percent of survived plants was 94.8%-96.4% and diseased root was decreased obviously. The control efficacy was more than 89% at the first year after treatment. The survived plants and plot yield of ginseng increased significantly and the control efficacy was around 40% at the second year. The best of the three treatments was by chloropicrin + organic manure.     

施肥对热带雨林下种植砂仁土壤氮矿化和硝化作用的影响

采用封顶埋管法(Close-TopIncubation)研究了施肥后西双版纳热带雨林下种植砂仁土壤的氮素净氨化、净硝化和净矿化速率。结果表明,种植砂仁的热带雨林土壤有机氮的净氨化、硝化和矿化速率明显受外来无机氮的影响,施入铵态氮肥后,土壤中的氨化速率明显提高(P<0.01),由对照土壤的-0.66(mg·kg-1·30d-1)增加至施肥处理土壤的1.65(mg·kg-1·30d-1),但硝化速率和矿化速率却显著降低(P<0.01),分别由对照土壤的6.79(mg·kg-1·30d-1)和6.13(mg·kg-1·30d-1)减少至施肥处理土壤的2.60(mg·kg-1·30d-1)和4.25(mg·kg-1·30d-1),导致了土壤中NH4+-N的积累。     

Epidemiology of beet necrotic yellow vein virus in sugar beet at different initial inoculum levels in the presence or absence of irrigation

A field experiment was set up in 1988 to study the development of rhizomania disease of sugar beet at different inoculum levels of beet necrotic yellow vein virus (BNYVV) in soil. Five, tenfold different, inoculum levels were created by addition of the approximate amounts of 0, 0.5, 5, 50 and 500 kg infested soil per ha (the latter corresponding to 0.01% v/v calculated to the tillage layer). A drip irrigation treatment was applied to study the influence of soil moisture on disease. Susceptible sugar beet, cv. Regina, was grown for three consecutive years.In the first year, root symptoms were not observed, but BNYVV-infected plants were detected by ELISA in low numbers at all inoculum levels at harvest. After late drilling in 1989, high numbers of infected plants, up to 90–100% in plots with the highest inoculum level, were detected already in June. Root symptoms were also observed from June onwards. In both these years disease incidence increased in time and was significantly influenced by the initial inoculum level. In the third year, the whole field was heavily diseased, and only for the non-irrigated plots incidence differed for different initial inoculum levels. The expression of symptoms by BNYVV-infected plants was influenced by initial inoculum level, thus by the amount and timing of primary infection.Root weight at harvest was not affected, but sugar content decreased with increasing inoculum level already in 1988, leading to a reduction in sugar yield of 10% at the highest inoculum level. In 1989, both root weight and sugar content decreased progressively with increasing inoculum level, resulting in sugar yield reductions of 11–66% (down to approximately 3000 kg ha^–1) for low to high inoculum levels compared to the control. As the control plots became contaminated, all yields were low in 1990, still showing a decrease with increasing inoculum level in the non-irrigated plots, but an overall mean sugar yield of 3323 kg ha^–1 for the irrigated ones.Sodium and -amino nitrogen content of the root, additional quality parameters determining extractability of sucrose, showed an increase and decrease, respectively, with increasing initial inoculum level already in the first year. The relative differences in contents compared to those from the control were largest for Na content. A significant negative correlation was found between Na (mmol kg^–1 root) and sugar content (% of fresh weight); linear for 1988, exponential for 1989 and 1990.In spring 1989, the infestation of individual plots was assessed using a quantitative bioassay estimating most probable numbers (MPNs) of infective units of BNYVV per 100 g dry soil. The relationship between the MPns determined and root weight, sugar content and sugar yield at harvest could be described by Gompertz curves. The increase in disease incidence with increasing MPN in 1989 was adequately fitted with a logistic equation.     

覆盖对烟田土壤酶活性及烤烟叶片荧光特性的影响

通过对烤烟大田3种不同覆盖方式的覆盖效应比较表明:覆盖明显增强了土壤过氧化氢酶和蔗糖酶活性,对脲酶活性有一定抑制作用;在烤烟生长前期,液膜覆盖处理土壤过氧化氢酶活性较对照和地膜覆盖处理分别平均提高5.72%、23.19%,且覆盖处理间差异达0.05显著水平;覆盖处理的蔗糖酶较对照平均提高0.8%,但3个处理间差异均不显...