沿江双季稻北缘区晚稻适宜品种类型及高产群体特征

研究沿江双季稻北缘区晚季籼稻和粳稻产量差异,明确适宜类型品种及高产形成机制。试验于2018—2019年在安徽庐江进行,以当地常规种植的17个籼稻和17个粳稻优质品种(系)为研究对象,比较和分析籼稻和粳稻在产量及构成、物质积累和生育进程方面的差异。结果表明,粳稻与籼稻总体上产量水平相当,但粳稻产量限制因子少,安全齐穗性有优势,具有更高的产量稳产性和生态安全性。高产粳稻主要是通过增加移栽–抽穗期干重来增加总干物质积累,以提高总颖花量和产量。不同穗型粳稻品种生育前中期不同阶段的干物质积累对总颖花量的影响差异较大,其中大穗型(每穗粒数102.3～112.0)和小穗型粳稻(每穗粒数52.0～99.7)干物质优势积累期分别为移栽–穗分化期和穗分化期–抽穗期,与总颖花量的相关系数达到0.709和0.829。进一步分析发现,大穗型粳稻品种移栽–穗分化期干物质积累受穗分化期分蘖数显著影响,而小穗型粳稻品种穗分化–抽穗期干物质积累由抽穗期分蘖数和单茎干重共同影响。综上所述,本研究认为粳稻是沿江双季稻北缘区适宜的双季晚稻品种类型,高产粳稻群体颖花量为33.8×10~3～41.0×10~3 m^–2<...     

基于MMC与CV模型的苗期玉米图像分割算法

针对苗期玉米田复杂土壤背景噪声,提出一种基于MMC（最大间隔准则）与CV（Chan-Vese）模型的玉米彩色图像分割算法。利用MMC对玉米彩色图像灰度化,用TV（全变分）滤波器对灰度图像进行去噪,用CV模型对去噪图像进行图像分割。试验结果表明,算法优于传统的颜色因子与Otsu组合算法,能有效去除图像中的小杂草和青苔,实现玉米目标提取,错分率为4.32%,漏分率为9.69%,相似度为86.57%。     

Evaluation of histological grade and histologically tumour‐free margins as predictors of local recurrence in completely excised canine mast cell tumours

Completeness of mast cell tumour (MCT) excision is determined by assessment of histologically tumour‐free margins (HTFM). The HTFM width necessary to prevent local recurrence (LR), recognized as histologic safety margin (HSM) in human oncology, has not been defined. We hypothesized that HTFM width would correlate with risk for LR and high‐grade tumours would require wider HTFM than low‐grade tumours. Records of dogs with completely excised MCTs were included. Signalment, two‐tier tumour grade, tumour size, HTFM width, recurrence and therapy data was collected. High‐grade (n = 39) tumours were more likely to recur than low‐grade (n = 51) tumours (35.9% versus 3.9%), P < 0.0001, with no association between HTFM width and LR. Twenty‐nine percent of low‐grade tumours had HTFM less than 3 mm; none recurred. Narrow (≤3 mm) histologic margins are likely adequate to prevent LR of low‐grade tumours. High‐grade tumours have significant risk of LR regardless of HTFM width.     

板栗新病害褐缘叶枯病及病原鉴定

板栗(Castanea mollissima)在山东省是一重要的干果树种.自2004年起,山东泰安、济南、潍坊、临沂等地相继发生一种新的叶部病害,板栗感病后,叶片上产生褐色的斑点,随后病斑迅速扩大,呈不规则大面积干枯,9月中、下旬开始大量落叶,10月中、下旬二次发芽抽稍,新发枝稍冬季枯死,极易诱发板栗疫病,引起树木整株死亡.近年来,该病逐年加重.2006年对泰安市徂徕山林场600hm2板栗林调查,发病率为100%,800余株10～15年生板栗树死亡,2007年死亡9000余株,减产近12万kg.为控制该病害的危害,生产上迫切需要确诊出该病害及病原,2006-2009年,笔者对该病害进行了系统的研究,旨在为研究病害的发生发展规律和防治措施的制定提供理论依据.     

中国鲜活农产品出口三元边际与定价能力研究——以中国水果对俄罗斯、日本和美国出口为例

鲜活农产品在中国农产品出口中占重要地位,其中水果是具有出口创汇比较优势的产品。本文采用2000-2013年HS-6位水果贸易数据,分析了中国水果出口总体特征以及对俄罗斯、日本和美国的出口特征,应用三元边际分析方法,对中国水果在三个市场的出口增长三元边际进行了测算,并进一步对水果出口定价能力进行估测。研究表明:集约边际对水果出口增长的拉动作用大于扩展边际,对俄罗斯和美国的出口沿着价格边际增长,对日本的出口沿着数量边际增长;中国水果对这三个市场的出口定价能力较弱,缺失定价主动权,原因是中国水果在每个市场上所占份额小以及出口企业互相压价。为进一步实现水果出口增长和提高出口定价能力,建议增加水果出口种类,实现水果出口沿着扩展边际增长;提高水果附加值,实现水果出口沿着集约边际增长;加强农产品质量安全监管,突破绿色贸易壁垒;提高企业进入国际市场的组织化程度,增强议价能力。     

Sustainable use of non-timber forest products: Impact of fruit harvesting on Pentadesma butyracea regeneration and financial analysis of its products trade in Benin

Pentadesma butyracea Sabine (Clusiaceae) is a multi-purpose tree that provides non-timber forest products (NTFPs). In particular, fruit almonds can be transformed into butter for cooking and cosmetics. During the present study, the following hypotheses were tested: (i) diameter structure of P. butyracea populations is independent of its fruit gathering intensity; (ii) P. butyracea seedling and sapling density and origin are independent of its fruit gathering intensity; (iii) P. butyracea fruit gathering and processing of its almonds are profitable activities and (iv) P. butyracea fruit collectors and almond transformers are receiving the lowest marketing margins in the commercial channel. The class distribution in the low-intensity harvesting sites showed a typical inverse J-shaped curve whereas the high-intensity harvesting ones showed an almost bell curve (G² = 23.93, p = 0.0008). After data analysis, all hypotheses turned out to be wrong except the hypothesis (iii). In order to assess the effects of fruit harvesting on natural regeneration of P. butyracea, we compared seedling and sapling density of regeneration originating from seeds and roots suckers in plots that had been differentiated according to fruit harvesting intensity. These plots were laid out in riparian forests, which are the natural habitats for the species in Benin. Observed seedling and sapling density was high (13,872 ± 7886 seedlings and saplings/ha) in low-intensity harvesting sites but very low (4200 ± 3810 seedlings and saplings/ha) in high-intensity harvesting sites (F = 17.16; p = 0.0006). However, there was no significant difference between root sucker density in either type of harvesting site (F = 0.79; p = 0.3861). Collection of P. butyracea fruits and subsequent processing of its almonds into butter is an important source of income for women involved in these activities. Commercial margin analysis showed that these women involved in almonds and butter trade, far from being exploited by traders, recuperate between 49% and 80% of the price paid by the consumer, depending on the quality of the product and the length of commercial channel used.     

SUSAN算法在植物叶缘特征提取中的应用

叶缘特征是植物种类识别和分类的一个重要依据。根据植物学中对叶缘的描述,设计了计算机辅助植物叶缘特征提取方案。首先采用改进的SUSAN算法检测植物叶缘锯齿,然后计算叶缘锯齿数量、尖锐度、偏斜度3个特征参数。对多种类型的植物叶进行测试,结果表明,利用改进的SUSAN算法能够有效检测植物叶缘锯齿,3个特征参数体现了不同类型叶缘的形状差异,叶缘特征提取方案可用于植物叶缘定量分类。     

模拟降水和氮沉降对准噶尔盆地南缘梭梭光合生理的影响

氮沉降和降水格局变化是目前全球气候变化背景备受关注的热点研究课题,也是荒漠生态系统的两个主要限制因子。因此,研究两者对荒漠植物的效应有助于深入了解荒漠生态系统对全球变化的响应。本文选择准噶尔盆地南缘荒漠地区的建群种梭梭(Haloxylon ammodendron)作为研究对象,设置自然降水(W0)与增加降水30%(W1)两个水分条件和自然氮沉降(N0)、增加氮素30 kg(N)·hm~(-2)·a~(-1)(N1)与增加氮素60kg(N)·hm~(-2)·a~(-1)(N2)3个施氮水平,连续处理2年,以探究降水、氮沉降及其交互作用对梭梭光合日变化及生理生态特征的影响。结果表明:降水、氮沉降及其交互作用对梭梭的净光合速率(Pn)日变化产生极显著正相关影响;同时根据梭梭Pn、胞间CO2浓度(Ci)及气孔限制值(Ls)的变化方向,推测梭梭光合"午休"主要由非气孔因素引起。此外,W0条件下,梭梭丙二醛(MDA)含量、抗氧化酶(POD、CAT、SOD)活性、可溶性蛋白(Pr)和可溶性糖(SS)含量均随施氮量增加而显著降低,脯氨酸(Pro)含量则呈先降低后增加的趋势;而W1条件下,梭梭MDA含量、抗氧化酶(POD、CAT、SOD)活性及渗透调节物质(Pro、Pr、SS)含量均随施氮量增加呈显著先增加后降低的趋势。两种水分条件下,除W1N1处理梭梭的Pro含量高于对照组外,其余处理均显著低于对照组;同时梭梭的MDA含量、抗氧化酶活性、Pr及SS含量也均显著低于对照组。综合分析结果表明:降水、增氮及其交互作用均有利于梭梭的生长,但其交互作用效应的强弱则取决于二者间的比例。     

中国对东北亚木质林产品出口增长模式分析——基于三元边际模型的测算

东北亚地区是中国重要的木质林产品出口市场,但近年来中国对东北亚地区木质林产品出口增幅日益减小。文中选取2000-2015年中国对东北亚地区木质林产品出口贸易数据,利用三元边际模型分析中国对东北亚地区木质林产品的出口增长模式。结果表明,在2000-2015年中国对东北亚地区木质林产品的出口增长驱动因素中,出口数量始终是最主要的。为刺激中国对东北亚地区木质林产品出口再增长,应加强国内森林认证体系的发展,坚持林产企业供给侧改革,实现"数量价格双驱动"的出口增长模式。     

商品猪胴体性能对分割销售后效益的影响

试验以深圳某集团销售外三元商品猪为研究对象,分析了商品猪不同胴体性能对分割销售效益的影响.结果表明,销售完成率与胴体背膘厚呈正相关,不同背膘厚的销售完成率差异极显著(P<0.01);销售完成率与胴体重呈正相关,不同胴体重的销售完成率差异显著(P<0.05);销售毛利率与胴体背膘厚呈正相关,不同背膘厚的销售毛利率差异极显...