Effects of gibberellic acid on tiller-bulb number and growth performance of Lilium davidii var. unicolor

Lilium davidii var.unicolor(Lanzhou lily)is an important economic crop in the northwest cold and arid regions of China.Effective regulation of tiller-bulb development and plant growth is the key to improving yield and quality of the lily.This study attempted to evaluate the effect of gibberellic acid(GA3)on tiller-bulb development and plant growth of Lanzhou lily by applying GA3 at various concentrations(0 mg/L,10 mg/L,30 mg/L,60 mg/L,and 100 mg/L)before planting and in the seedling period.Results showed that the 60-mg/L GA3 application had an inhibiting effect on tiller-bulb formation and increased the ratios of single and double bulbs but decreased the ratios of bulbs with three or more tiller bulbs,as com pared to the control(CK)and other GA3 treatments.The difference in flower number did not reach significant levels among the treatments.The tillering-related endogenous hormones IAA(indole-3-acetic acid)and Z(zeatin)content de creased,while IAA/Z increased with the 60-mg/L GA3 treatment during tiller initiation.And also,the shoot-bulb number and total daughter-bulb number decreased significantly with the 60-mg/L GA3 treatment.Furthermore,the 10-mg/L GA3 application promoted growth of Lanzhou lily significantly and resulted in an increase in plant height;bulb diameter;bulb circumference;and biomass of shoots,bulbs,fibrous roots,and the whole plant.Therefore,GA3 application is promising as a new regulation method for inhibiting tiller-bulb development and promoting bulb growth in Lanzhou lily production.

农户土地承包经营权抵押风险预期影响因素及防控模拟研究

基于农户抵押融资风险视角对影响农村土地承包经营权抵押贷款风险预期的因素进行深入剖析,模拟构建土地承包经营权抵押贷款风险管理与防控体系。运用多元Logistic回归模型与Boe-Tie理论分析框架。研究结果表明:第一,自变量家庭年纯收入、就业情况满意度、土地承包经营权抵押贷款意愿、承包地抵押价值、'三权分置'普法宣传、村干部对土地承包经营权抵押态度、承包地离村住宅距离、承包地是否连片、农业环境是影响农户土地承包经营权抵押贷款风险预期的主要因素。第二,运用Bow-Tie分析框架,以政府、银行、农户三方主体为立足点,从主动威胁源、风险点防控与被动后果应急处置措施的双重视角,构建了'农户土地承包经营权抵押贷款无法偿还'的风险管理和防控策略模拟体系,采取相对应的具体措施屏障应对可能存在的潜在'危险'风险与导致'后果'。研究结论:结合调查实际与理性行为理论、博弈论和福利经济学等相关理论,农户对土地承包经营权抵押贷款风险预期决策处在'稳定生存静态理性'和'经济发展动态感性'兼顾的阶段,在农户的'价值理性偏好判断'形成之前,二者间没有明显的过渡趋势。通过对成熟区、发展区和萌芽区的不同农村试点提出市场调节分散模式、政府调控引导模式和集体组织控制模式的差异化抵押贷款风险防控施策模式,为坚决推进和打好防范化解'抵押贷款'系统性重大风险的攻坚战提出针对性的借鉴性建议。

Comparison of soil physico-chemical properties under different land-use and cover types in northeastern China's Horqin Sandy Land

The Horqin Sandy Land of northeastern China was originally a grassland with plenty of water and lush vegetation dominated by palatable grass species along with sparsely scattered woody species. However, it has experienced severe desertification in recent decades due to its fragile ecology together with inappropriate human activities. Currently, the landscape of the Horqin Sandy Land is dominated by irrigated croplands and sand dunes with different degrees of vegetation cover, as the region has become the most important part of the semiarid agro-pastoral ecotone of northern China. In this study, we compared soil physical and chemical properties under different land-use and cover types （irrigated cropland, rainfed cropland, sandy grassland, fixed dunes, and mobile dunes）. We found that soil particle size distribution; organic C, total N, and total mineral element, microelement, and available microelement and nutrient contents; pH; CEC; and bulk density differed significantly among the land-use and cover types. In general, soil quality was highest in the cropland, intermediate in the sandy grassland, and lowest in the dunes. The most important soil quality attribute, soil organic carbon （SOC） storage, decreased in the fol-lowing order： irrigated cropland （5,699 g/m^2） 〉 sandy grassland （3,390 g/m^2） 〉 rainfed cropland （2,411 g/m^2） 〉 fixed dunes （821 g/m^2） 〉 mobile dunes （463 g/m^2）. SOC was significantly positively correlated with a large proportion of the other soil physico-chemical parameters. Our results suggest that the key issue in restoration of the degraded soils will be to increase SOC storage, which would also create a high potential for sequestering soil C in desertified areas of the Horqin Sandy Land.

The response of Caragana microphylla seedlings to water table changes in Horqin Sandy Land,China

This paper focuses on the growth response of Caragana microphylla seedlings to changes of artificially controlled water table in Horqin Sandy Land, China. Monitoring results of soil water content shows that soil moisture is closely correlated to groundwater depths. Soil volumetric water increased rapidly when close to water sources and finally stabilized in a saturated state. The soil moisture trend of CK （control） increased gradually at 0-50 cm of soil depth then decreased to 4% below 50 cm soil depth. C. microphylla can adapt to different soil environments by changes in ecological and physiological characteristics. By comparing the ecological characteristics of C. microphylla seedlings at various water tables, we found that a shallow water table of 40 cm depth inhibited seedling groundwater depth of 120 em was more advantageous for plant growth because of weak ecological characteristics. A height and canopy growth of C. microphylla seedlings. During the first two years, the most suitable water depth for root biomass was 120 cm, and 180 cm for root length. The growth of vertical roots is positively correlated with groundwater depth, and root thickness is the determinate factor for root biomass while the fine root is the determinate factor for root length. A thick root would grow much more in a natural drought environment while access to ground water promotes the growth of fine roots.

Screening of cellulose decomposing fungi in sandy dune soil of Horqin Sandy Land

Cellulose decomposing fungi play an important role in litter decomposition and are decisive in nutrient cycling in sandy land ecosystems. Thirty-one strains were isolated to select efficient cellulose decomposers, and four efficient cellulose decomposing fungi （NM3-1, NM3-2, NM3-3, and NM3-4） were screened using a CMC （carboxymethyl cellulose） carbon source in dune soil of Horqin Sandy Land. They were identified as Asperigillus calidoustus, Fusarium oxysporum, Fusarium solani, and Hypocrea lixii by rDNA-ITS molecular biological methods. Cloth decomposition rates were 15.71%, 15.89%, 17.29%, and 17.89% by the four efficient decomposers incubated for 30 days, respectively. Screening of efficient cellulose decomposers can not only increase the dune soil functional microbe bank, but can also accelerate litter decom- position and available nutrient input in the Horqin Sandy Land.

科尔沁沙地防沙治沙实践与生态可持续修复浅议

地处中国北方农牧交错带东南端的科尔沁沙地,本应是水草丰美的疏林草地景观,然而脆弱的生态环境基质条件叠加气候变化与不合理的人类活动影响,使其成为现代沙漠化最严重的区域之一。在中国防沙治沙的实践进程中,科尔沁沙地率先实现了沙漠化逆转,但在全球变化背景下该区的防沙治沙形势依然严峻。本文重点梳理了科尔沁沙地在过去几十年防沙治沙中形成的独具特色的治理模式及成效,归纳了科尔沁沙地歼灭战攻坚行动启动以来各省区的行动方案,探讨分析了新时代防沙治沙面临的主要问题与挑战,并针对性地提出了生态可持续修复的对策建议,以期为科尔沁沙地生态环境高水平保护修复与经济社会高质量发展提供科技支撑。

Pictet-spengler/transamination cascade reaction of indoles for modular synthesis of marinoquinoline analogues

The Pictet-Spengler/transamination cascade reaction enables modular synthesis of marinoquinoline analoguesthrough three-component indole ring-expansion/cyclization in the manner of novel N1–C2 cleavage of indoles.This metal-free protocol exhibits very broad functional group tolerance with up to quantitative yields. Preliminarystudies on the antitumor activity of the resultant marinoquinoline analogues reveal that the indolyl-attachedpyrrolo[2,3-c]quinoline product (5d) shows great potential (IC50 of 0.32 μg/mL to HeLa cells) as a promisinganticancer agent in clinic.

A pH-switched mesoporous nanoreactor for synergetic therapy

Zinc oxide nanoparticles （ZnO NPs）, as a new type of pH-sensitive drug carrier, have received much attention. ZnO NPs are stable at physiological pH, but can dissolve quickly in the acidic tumor environment （pH 〈 6） to generate cytotoxic zinc ions and reactive oxygen species （ROS）. However, the protein corona usually causes the non-specific degradation of ZnO NPs, which has limited their application considerably. Herein, a new type of pH-sensitive nanoreactor （ZnO-DOX@F-mSiO2-FA）, aimed at reducing the non-specific degradation of ZnO NPs, is presented. In the acidic tumor environment （pH 〈 6）, it can release cytotoxic zinc ions, ROS, and anticancer drugs to kill cancer cells effectively. In addition, the fluorescence emitted from fluorescein isothiocyanate （FITC）-labeled mesoporous silica （F-mSiO2） and doxorubicin （DOX） can be used to monitor the release behavior of the anticancer drug. This report provides a new method to avoid the non-specific degradation of ZnO NPs, resulting in synergetic therapy by taking advantage of ZnO NPs-induced oxidative stress and targeted drug release.

Subpixel imaging method with area-array CCD sensors and experiment

A novel high resolution imaging technique-subpixel imaging with area-array CCD sensors-is presented. The imaging method is practical as demonstrated by the computer simulation and expetimental results. It is useful to reduce the effective focal length and enhance the spatial resolution. As there are no moving elements, the subpixel imaging system will be suitable for space application.