棉花黄萎病菌致病型的AFLP分析

 选用41个棉花黄萎病菌(Verticillium dahliae)代表菌系,在温室条件下,对4个棉花品种鄂荆1号(感)、中棉所12(耐)、文-5(抗)和唐棉2号(抗)进行致病性测定,结果可将供试菌系分为落叶型与非落叶型2类。选取8对AFLP引物PCR扩增的结果中,统计带型稳定、清晰且有多态性的条带,共169条作系统聚类分析,将上述菌系分为2大类,第一类为非落叶型菌系,包括10个非落叶型菌系和1个过渡菌系;第二类为30个落叶型菌系。根据聚类分析建立树状图,发现菌系与地理来源存在一定的相关性,而依据菌系致病力强弱分类则相关关系不大。选用25对EcoRⅠ和MseⅠ引物组合,对供试的41个V.dahliae进行AFLP扩增,筛选到2对引物E64(GACTGCGTACCAATTCGAC)、M53(GATGAGTCCTGAGTAACCG)和E49(GACTGCGTACCAATTCCAG)、M65(GAT-GAGTCCTGAGTAAGAG),能分别扩增出433bp和110bp2条仅为V.dahliae非落叶型菌系独有的特异片段,可将落叶型与非落叶型菌系分开,这2条特异片段被命名为EM₄₃₃和EM₁₁₀。     

香蕉束顶病毒(BBTV)侵染对寄主内源激素的影响

 本试验用ELISA方法测定了香蕉感染束顶病毒(BBTV)后植株体内的3种内源激素,赤霉素(GA₃)、玉米素类(iPAs)和脱落酸(ABA)的变化。结果表明,感株的GA₃水平在侵染过程中虽有微弱增加,但含量和增长速度显著低于健株对照;iPAs在接种BBTV第14天后明显下降,并维持较低水平;ABA在BBTV侵染后被大量诱导增加并不断积累,在接种后第35天测定含量最高,为对照的3.34倍。试验还同时检测了BBTV在侵染过程中的运转。用间接ELISA测定的接种叶和顶叶的BBTV含量显示:接种21天后BBTV在接种叶和顶叶中还大量增殖,呈系统性分布。但寄主的症状在接种35天后才逐渐在顶叶表现。以上结果表明:香蕉束顶病的症状表现似乎主要与病株中的内源激素的失调有关,而与BBTV在体内的运转并不直接相关     

棉酚和单宁酸对棉铃虫幼虫生长和消化生理的影响

作者利用昆虫人工饲料测试了棉酚和单宁酸对棉铃虫幼虫生长、营养指标以及中肠主要蛋白酶活力的影响。结果表明,棉酚和单宁酸均能显著地抑制幼虫的生长,但二者之间无交互作用,其中单宁酸的作用较棉酚强。含3％棉酚或单宁酸的人工饲料,饲喂4龄幼虫48h后,可引起幼虫近似消化率减小和食物转化率增大,但食物利用率无显著变化。棉酚在离体条件下对类胰蛋白酶和类胰凝乳蛋白酶活力有不同程度的抑制作用,但在活体条件下,上述酶活力无显著变化,仅有中肠总蛋白酶活力下降。单宁酸在离体条件下对类胰蛋白酶有抑制作用,而对类胰凝乳蛋白酶活力无作用:在活体条件下,仅总蛋白酶活力和弱碱性类胰蛋白酶活力显著下降。由此可知,棉酚和单宁酸对棉铃虫的生长抑制作用与幼虫中肠蛋白酶活力和食物消化率的降低有关。     

棉花调亏灌溉的生理基础研究

以盆栽棉花为材料,通过苗期和现蕾期不同程度的亏水处理(低、中、高三个水平),对调亏灌溉节水效应及生理机制进行了研究。结果表明:适时适度的水分亏缺可使植株旺盛的营养生长得以有效控制,株型和根冠比都更为理想。调亏期间,蒸腾速率和气孔导度都明显下降,而光合速率下降不明显,复水后光合速率和气孔导度明显恢复且接近或高于对照;此外,水分亏缺不仅影响棉桃的数量,而且影响单果重。表明适度的亏水处理可使水分利用效率明显提高,而经济产量接近或高于对照,同时节水20%以上。     

限水灌溉对转基因抗虫棉产量形成的影响

采取限水灌溉的方法,研究了灌水对棉花产量形成的影响。研究结果表明,合理灌水能促进棉花开花成铃,延长最佳成铃时段,增加棉株优质节位的成铃数,单株籽棉干物重增加23.4%～61.9%,产量提高16.8%～45.3%。灌水量以675m3/hm2效果最好,灌水效益高达0.57kg/m3,灌水量达1350m3/hm2增产幅度下降,灌水效益仅0.21kg/m3。     

简论我国施药技术的发展趋势

环境安全和食品安全已引起世界各国的高度重视,我国政府在全面建设小康社会的同时,已把治理农业环 境、发展可持续农业列入重要的议事日程。本文试图从施药技术的3个方面--药械、农药、施药方法来探讨我 国施药技术的发展趋势,并提出了作者的一些观点,力图为我国施药技术的发展提供一些参考依据。     

Critical periods for weed control in cotton in Turkey

Field studies were conducted over 4 years in south‐eastern Turkey in 1999–2002 to establish the critical period for weed control (CPWC). This is the period in the crop growth cycle during which weeds must be controlled to prevent unacceptable yield losses. A quantitative series of treatments of both increasing duration of weed interference and of the weed‐free period were applied. The beginning and end of CPWC were based on 5% acceptable yield loss levels which were determined by fitting logistic and Gompertz equations to relative yield data representing increasing duration of weed interference and weed‐free period, estimated as growing degree days (GDD). Total weed dry weight increased with increasing time prior to weed removal. Cotton heights were reduced by prolonged delays in weed removal in all treatments in all 4 years. The beginning of CPWC ranged from 100 to 159 GDD, and the end from 1006 to 1174 GDD, depending on the weed species present and their densities. Practical implications of this study are that herbicides (pre‐emergence residual or post‐emergence), or other weed control methods should be used in Turkey to eliminate weeds from 1–2 weeks post‐crop emergence up to 11–12 weeks. Such an approach would keep yield loss levels below 5%.     

浙江地区不同品种紫花苜蓿不同刈割期二茬性状表现

对不同秋眠级别的紫花苜蓿Medicago sativa品种进行适应性试验,研究不同品种不同刈割期株高、分蘖数、根系、茎叶比及生物学产量间的变化,为生产推广提供指导.     

海河平原区棉花饲用黑麦复种方式及水肥利用效率分析

2011年10月-2014年10月连续3年在河北省任县安排了定位试验,通过饲用黑麦不同播期与棉花构建几种棉草复种茬口搭配方式,从产量、经济效益、水分利用效率和养分利用效率以及对土壤肥力影响等方面综合分析棉花饲用黑麦复种的可行性及复种方式。结果表明,棉花可与饲用黑麦复种,为降低饲用黑麦对棉花的影响,饲用黑麦可适当推迟到10月20日播种,次年4月底收获,效益可提高5470.1元·hm^-2。棉花饲用黑麦复种与棉花单作相比,平均水分利用率提高16.49%;水分经济利用效率提高56.54%;并且土壤有机质平均增长幅度提高5.71%,土壤含盐量平均降低幅度达到23.72%,土壤改良效果明显;是适用于该区域的高效复种模式。     

Assessing exterior egg quality indicators using machine vision

ABSTRACT

1. The objective of this study was to develop a machine vision method for analysing exterior parameters of chicken eggs to automate the stage of primary sorting.

2. The developed algorithm based on predetermined thresholds calculated egg quality indicators, including geometric dimensions, shape index and the mottling grade. The algorithm was implemented with an experimental setup that combined the image-based and the candling methods. A total of 400 egg samples were analysed.

3. Comparison of results of the algorithm with those obtained using the traditional manual method showed that mean value of radii values difference was 0.095 ± 0.058 mm for the sharp and 0.080 ± 0.047 mm for the blunt end of the egg, with standard deviations of 0.58 mm and 0.49 mm, respectively.

4. The correlation coefficient between the shape index values determined by the two methods was 0.93; the standard deviation of absolute differences between corresponding values was 1.05%.

5. The results of mottling grade estimation were compared using F-measure and confusion matrix.

6. The results allow the possibility to perform the assessment of egg exterior quality factors in an automatic mode, independent of the expertise of a grader.