气候条件对冬小麦穗粒数的影响研究

长期定位试验研究气候条件对冬小麦穗粒数的影响结果表明 ,冬小麦穗粒数主要受返青后 5日滑动平均气温首次≥ 4℃之日～雌雄蕊原基分化时 (即拔节开始天数 )的影响 ,并受其至挑旗期平均最低气温和至抽穗期日照时数的制约。各因素对冬小麦穗粒数的影响大小依次为天数 >日照时数 >平均最低气温。冬小麦高产栽培还应协调好穗数、穗粒数和千粒重三者之间的关系     

植保四轴飞行器的模糊PID控制

针对当前植保四轴飞行器在作业过程中自身载荷发生改变后的飞行控制性能下降、抵抗环境扰动能力差的问题,该文改进了传统比例积分微分(proportion,integration,differentiation,PID)控制算法,提出了一种模糊PID控制算法。该文通过研究四轴飞行器的姿态解算和飞行原理,设计了以STM32系列的单片机为核心处理器的四轴飞行控制系统。采用AHRS模块实时解算飞行器姿态参数,结合模糊控制和PID控制算法调节电机的输出量来控制飞行姿态。试验结果表明:与传统PID相比,模糊自整定PID控制算法适应性强,参数整定简单,系统的动态响应能力和稳定性获得了提高,实现了四轴飞行器的稳定飞行。该文为植保无人机控制算法研究提供了一定的参考。     

云贵高原岩溶地区生态气候类型区划

利用主成分分析和动态逐步聚类方法进行气候类型区划，较好地综合了多种气候，地理和生态因素，避免了只考虑了几个经验性气候要素作为区划指标的某些弊端，使区划结果更客观定量，更符合实际情况。     

Cross-enhancement: enhanced biodegradation of isothiocyanates in soils previously treated with metham sodium

Rates of degradation of 2-propenyl isothiocyanate (PrITC), benzyl isothiocyanate (BeITC) and 2-phenylethyl isothiocyanate (2-PeITC) in a soil known to biodegrade methyl isothiocyanate (MITC) at an accelerated rate, but never previously exposed to the other ITCs, were higher (persistence in soil increased by 1150, 80 and 100%, respectively,) than in a similar non-degrading soil. The rate of degradation of the same three ITCs was significantly lower in sterilised (autoclaved) soils than in the degrading soil. These results indicate that the three ITCs are susceptible to enhanced cross-biodegradation in soils where enhanced biodegradation of MITC has been induced by use of metham sodium soil fumigant. When Brassica plant tissue containing sinigrin (2-propenyl glucosinolate) as the predominant glucosinolate (GSL) was added to the degrading soil, the amount of PrITC present after 24 h was significantly lower than in the non-degrading soil at the same amendment rates. The toxicity to an insect test organism of the PrITC produced from the biofumigant plant tissue was correlated with the concentration of PrITC measured in the two soils, with 67% more plant tissue required in the degrading soil to cause 100% mortality as in the non-degrading soil (3.0 vs 5.0 mg g⁻¹). The effectiveness of biofumigation using ITC-producing Brassica plants may be diminished in soil suffering from enhanced biodegradation of MITC.     

藕炭疽病病原及生物学特性

 该病为国内首次报道,在南宁、贵港等市县近年来有日趋严重之势。4~5月见病,夏秋时节病重,病叶率达70%以上。     

The crucial role of calcium interacting with soil pH in enhanced biodegradation of metam-sodium

Enhanced biodegradation of soil-applied pesticides has long been correlated with soil pH above ca 6.5-7.5, but the possibility of confounding or interdependence with calcium, given that soil calcium concentration increases exponentially as pH rises above that range, has not previously been studied. Enhanced biodegradation of the broad-spectrum biocide metam-sodium was readily induced de novo in a naturally acid sandy soil (pH 4.2 measured in 0.01 M CaCl2) by multiple treatments, but only when the pH and calcium concentration were raised simultaneously using calcium carbonate (lime). Enhanced biodegradation was not induced when soil pH alone was raised with magnesium carbonate, nor when calcium alone was raised using calcium chloride. In limed sand treated monthly for 12 months, the degradation rate increased to where dissipation was complete within 24 h of application after the fifth metam-sodium treatment at pH 7.8 and after the eighth metam-sodium treatment at pH 6.8. Pesticide concentration was reduced, but not eliminated, at pH 5.8 and was unchanged at pH 4.8. When metam-sodium was applied bi- and tri-monthly, the degradation rate also increased when soil pH was raised with calcium carbonate, but to a lesser extent than with monthly applications. In an acid loam soil amended to the same pH values with calcium carbonate and treated monthly, there was no correlation between soil pH or calcium concentration and degradation. The results reveal the crucial interdependence of pH and calcium concentration in enhancement of biodegradation of soil-applied pesticides, but confirm that the phenomenon ultimately depends on interaction with soil type and frequency of application factors, all of which probably together act to affect the abundance, composition and activity of the soil microbial biomass.     

AAHA dental care guidelines for dogs and cats

The purpose of this document is to provide guidelines for the practice of companion animal dentistry for the veterinary profession. Dental care is necessary to provide optimum health and quality of life. Diseases of the oral cavity, if left untreated, are often painful and can contribute to other local or systemic diseases. This paper includes guidelines for materials and equipment, dental cleaning and evaluation, client communication, and pet home care.     

SCINTIGRAPHIC CHARACTERIZATION OF THE EQUINE FOREDIGIT AND METACARPOPHALANGEAL REGION FROM BIRTH TO SIX MONTHS OF AGE

Both foredigits and metacarpophalangeal joints of six Quarter Horse foals were scanned serially to six months of age using ⁹⁹Tc-methylene diphosphonate. Dorsal scans were made on day 1 and at two, four, six, ten, 14, 18, 22 and 26 weeks of age. Scans were assessed visually for distal third metacarpal, proximal phalangeal, and middle phalangeal physeal appearance and closure. Scans were also evaluated by computer region-of-interest (ROI) and line-profile analysis to characterize the physes quantitatively. Physeal region radioactivity relative to a disphyseal reference region was greatest at four weeks for all physes. Scintigraphic physeal closure of all physes occurred at approximately six months of age with a range of four and one half to greater than six months. The study was conducted to allow better assessment of diffuse and focal physeal disease by determining developmental times at which normal physeal region radioactivity has decreased enough to not obscure abnormal radioactivity and by quantifying scintigraphic physeal appearance which enables computer analysis to detect visually indeterminate physeal abnormalities.     

Genetic Variation and Virulence on Lr26 in Puccinia triticina

ABSTRACT The genetic relationships between isolates of Puccinia triticina virulent on wheat with the Lr26 resistance gene were studied. The diversity within and between isolates of P. triticina from Israel, Europe, and the United States was determined by virulence on near-isogenic Thatcher lines and by random amplified polymorphic DNA. According to the molecular markers, isolates that were virulent on Lr26 had diversity levels similar to those of Lr26 nonpathogenic isolates. Distances between subpopulations of isolates virulent and avirulent on Lr26 varied and were unrelated to the Lr26 virulence phenotype. Cluster analysis suggested four groups, three of which were closely associated with the geographical origin of the isolates-Israel, the United States, and Europe. All four groups included both Lr26 virulent and avirulent pathotypes. The results showed that Lr26 virulent rust pathotypes are as genetically dissimilar as the rest of the population. The cluster analysis showed that the rust population in Israel includes at least two different subpopulations, both of which contain Lr26 virulent and Lr26 avirulent isolates.