Screening Capsicum species of different origins for high temperature tolerance by in vitro pollen germination and pollen tube length

Successful fruit set depends on several reproductive processes including pollen germination and tube growth processes. An experiment was conducted to determine the effects of temperature on pollen germination characteristics and to identify species/genotypic differences in Capsicum using the cumulative temperature response index (CTRI) concept. Pollen was collected from plants of seven genotypes from five Capsicum species, adapted to various parts of the world and grown outdoors in large pots. The pollen was subjected to in vitro temperatures ranging from 15 to 50 °C at 5 °C intervals. Pollen germination and tube lengths were recorded for all species after 24 h of incubation at the respective treatments. Species/genotypes differed significantly for in vitro pollen germination percentage and pollen tube length with mean values of 78% and 734 μm, respectively. The mean cardinal temperatures (T_min, T_opt, and T_max) averaged over genotypes, were 15.2, 30.7, and 41.8 °C for pollen germination and 12.2, 31.2, and 40.4 °C for pollen tube growth. The CTRI of each species/genotype calculated as the sum of eight relative individual stress response values, such as maximum pollen germination, maximum pollen tube length; T_min, T_opt, and T_max temperatures of pollen germination, and pollen tube lengths, identified species tolerance to high temperatures. Capsicum annum cv. Mex Serrano from Mexico was identified as tolerant, C. chacoense cv. 1312 and C. spp. cv. Cobanero from Argentina and Guatemala, respectively as intermediate and C. frutescens cv. Early Spring Giant from China, C. annum cv. Long Green from South Korea, C. spp. cv. NM89C130 and C. pubescens cv. 90002 from Guatemala as sensitive to high temperatures. The tolerant species/genotypes can be used in breeding programs to develop new genotypes that can withstand high temperature conditions both in the present climate and particularly in a future warmer climate.     

论野火的三属性

野火泛指发生于野外植被中的火、归纳发现有３个基本属性,自然性,灾害性和工具性,对这３个属性进行明确的定义和认识,有助于理解野火的意义,为研究和生产奠定科学系统的理论基础。自然属性一是指其自然存在、二是指其对自然界有影响,三是指其他受其他自然因子制约。灾是自然界不可控事件造成的超越一定程度界线的损失。灾害属性即经济属性。每一次火都造成巨大的经济损失,包括林资源和草资源预防和扑救开始。工具是指可以拿来     

Estimation of urban tree canopy cover using random point sampling and remote sensing methods

Trees play an important role in urban areas by improving air quality, mitigating urban heat islands, reducing stormwater runoff and providing biodiversity habitat. Accurate and up-to-date estimation of urban tree canopy cover (UTC) is a basic need for the management of green spaces in cities, providing a metric from which variation can be understood, change monitored and areas prioritised. Random point sampling methods, such as i-Tree canopy, provide a cheap and quick estimation of UTC for a large area. Remote sensing methods using airborne Light Detection And Ranging (LiDAR) and multi-spectral images produce accurate UTC maps, although greater processing time and technical skills are required. In this paper, random point sampling and remote sensing methods are used to estimate UTC in Williamstown, a suburb of Melbourne, Australia. High resolution multi-spectral satellite images fused with LiDAR data with pixel-level accuracy are employed to produce the UTC map. The UTC is also estimated by categorising random points (a) automatically using the LiDAR derived UTC map and (b) manually using Google Maps and i-Tree canopy software. There was a minimum 1% difference between UTC estimated from the map derived from remotely sensed data and only 1000 random points automatically categorised by that same map, indicating the level of error associated with a random sampling approach. The difference between UTC estimated by remote sensing and manually categorised random point sampling varied in range of 4.5% using a confidence level of 95%. As monitoring of urban forest canopy becomes an increasing priority, the uncertainties associated with different UTC estimates should be considered when tracking change or comparing different areas using different methods.     

试论金属切削刀具涂层

本文简要介绍了现代金属切削刀具的重涂技术的产生、技术特点及应用。     

低温氮气油雾对陶瓷刀具加工镍基K424合金的影响

在于切削、低温氮气和低温氮气油雾3种冷却润滑条件下,通过Sialon陶瓷刀具和SiC晶须增韧Al2O3陶瓷刀具车削K424镍基高温合金的实验,研究了低温氮气及油雾对刀具磨损和表面粗糙度的影响,开发了一个新的冷却系统以获得低温氮气.试验结果表明,切深线沟槽磨损严重限制陶瓷刀具使用寿命,与干切削相比,使用低温氮气和低温氮气油雾增加了切深线沟槽磨损速率,但降低了已加工表面的质量.     

CTM系列汽车拖拉机综合测试仪在汽车滑行阻力系数测定中的应用

介绍了汽车滑行阻力系数的测定方法,理论分析和试验结果均表明:应用CTM系列汽车拖拉机综合测试仪,在测定汽车滑行距离的同时,测定汽车滑行阻力系数的方法简便、可靠。     

利用天津农业科技信息网获取农业信息

介绍了天津农业科技信息网的远程终端用户拨入设置方法,并对如何利用天津农业科技信息网进行信息的查询、检索进行阐述,较详细地介绍了几种在因特网上检索信息资料的方法,同时,列出了一些常用的检索工具和农业方面的网址。     

刀具的可靠性及其分析

讨论了刀具寿命的失效机理，为提高刀具的可靠性提供理论依据。     

多工序组合弯曲模的设计

通过对细长类零件的工艺性分析，讨论了多工序组合安排的问题，进行了多工序弯曲模的分析与设计。     

机床误差对螺旋锥齿轮齿形的影响规

基于螺旋锥齿轮齿面分析的数学模型,采用最优化算法和一种新的计算齿形误差的方法,计算了误差齿面与理论齿面在理论齿面法线方向的齿形误差.通过引入机床调整误差和刀具参数误差,分析了各种误差对螺旋锥齿轮齿形的影响规律,以图形的方式表示了误差齿面相对于理论齿面的偏离方向以及误差值的大小,为机床的精度设计、齿形误差的修正以及指导实际加工提供了理论依据.通过实际的磨齿加工和检测对算法以及分析结果进行了验证.