Zinc biofortification of maize (Zea mays L.): Status and challenges

Zn deficiency is one of the leading health problems in children and women of developing countries. Different interventions could be used to overcome malnutrition, but biofortification is most impactful, convenient, sustainable and acceptable intervention. Maize is one of the major crops grown and consumed in the regions with prevalent Zn malnutrition; therefore, this is suitable target for Zn biofortification. Zn biofortification of maize could be achieved through agronomic and genetic approaches. Discussion of agronomic approaches with genetic approaches is prerequisite because soils in developing countries are deficit of Zn and availability of Zn in soils is mandatory for estimating the genetic responses of maize genotypes through genetic approaches. Seed priming, foliar and soil applications are agronomic tools for biofortification, but solo and combined applications of these treatments have different effects on Zn enrichment. Genetic approaches include the increase of Zn bioavailability or increase of kernel Zn concentration. Zn bioavailability could be increased by reducing the anti‐nutritional factors or by increasing the bioavailability enhancers. Kernel Zn concentration could be improved through hybridization and selections, whereas genetically engineered attempts for improving Zn uptake from soil, loading in xylem, remobilization in grains and sequestration in endosperm can further improve the kernel Zn concentration. Key challenges associated with dissemination of Zn biofortified maize are also under discussion in this draft. Current review emphasized all of above‐mentioned contents to provide roadmap for the development of Zn biofortified maize genotypes to curb the global Zn malnutrition.     

Male sterility in soybean: Occurrence,molecular basis and utilization

In plants, male sterility (MS) is a specific breeding target trait. With the advancements in agriculture, utilization of heterosis breeding in hybrid production through MS lines has become the main breeding tool of various cross‐pollinated and even self‐pollinated crops. Soybean is an essential source of oil and protein; however, the low yield is a major factor limiting its development. Soybean MS mainly comprises cytoplasmic‐nuclear MS and nuclear/genic MS (NMS/GMS), which can effectively utilize heterosis to improve soybean yield. This review outlines the recent research progress on the development of new genetically MS lines, exploring the underlying molecular mechanism of MS, identification and cloning of MS and fertility restoration genes, and the application of MS lines. We further discussed and prospected the future developmental scenario direction of the soybean MS, based on the previous studies of other crops sterility system. Moreover, this review also provides comprehensive information for better application of MS to soybean breeding programme.     

西瓜的需肥特点及施肥技术

西瓜营养丰富,果肉味甜,能降温去暑,是人们喜食的一类水果。西瓜生长过程中需肥量较多,如果营养不足或养分比例不当,会严重影响其产量和品质。在充分了解西瓜的需肥特点之后,提出应根据西瓜的长势、生长规律,注意氮、磷、钾三元素的合理搭配以及有机肥和化肥的互补作用,进行合理施肥,才能取得西瓜的高产。     

基于径向基网络的含缺陷管道安全系数修正

安全系数是管道完整性评价方法的重要参数之一,传统评价方法仅考虑了管道所处地区等级对其影响,未能全面评价管道的真实安全状态。提取管道相关风险因素,比较各因素间相对重要程度并建立表征不同风险状态的分值体系,根据所得风险分值对安全系数进行修正,使得修正后的安全系数能够反映含缺陷管段实际风险状态;结合径向基网络方法的自学习特点,将各风险因素作为输入,修正后的安全系数作为输出,建立基于径向基网络的管道安全系数计算模型。由模型训练得出的修正安全系数与测试样本吻合度较好,验证了模型的准确性。结果表明:修正安全系数在考虑地区等级的基础上同时引入了其他重要风险因素的影响,为管道完整性评价中的安全系数取值提供了新的思路。     

鱼类性别决定的遗传基础研究概况

动物从受精卵发育到具有不同性别特征的个体是一个奇妙而又严谨的过程,是人类长期以来试图揭示的自然现象。上世纪90年代初在人类Y染色体上发现了性别决定基因SRY[1],进而发现了一个新的Sox基因家族[2]。上述基因的发现,促进了以哺乳类为代表的动物性别决定和分化机制研究。由于鱼类在脊椎动物中的特殊进化地位、庞大的种类数量以及显著的社会经济价值,鱼类的性别决定研究一直受到遗传和发育学者的重视。尽管离最终阐明鱼类性别决定的机制还有距离,但近20多年来鱼类性别决定的遗传基础研究已取得不少重要进展。本文试图根据现有文献资料,…     

大学计算机基础实验系统的开发与应用

大学计算机基础课程的一个最重要的教学目就是让学生掌握计算机基本应用技能,可见上机实践在课程中重要性.我们开发本系统就是以任务驱动式的学习方式让学生学习起来目的明确、效果显现、更有成就感,从而激发对计算机应用知识的兴趣,促进学生自主学习,为今后学习和应用计算机打下良好基础.     

中等职业学校《机械基础》课程教学方法探讨

《机械基础》课程是中等职业学校机械类、机电类等专业的一门必修课程,具有知识面广、点多、内容抽象、实践性较强等特点,是较难掌握的一门课程。文章根据教学经验,针对《机械基础》课程教学方法提出了一些观点与看法,以其起到提高教学质量与效果的作用。     

Morphological Basis of Resistance in Cotton to the WhiteflyBemisia Tabaci

The morphological basis of resistance to the whiteflyBemisia tabaci Genn. (Aleyrodidae: Hemiptera) was studied. The plant characters examined were leaf area, thickness of leaf lamina, hair density, hair length, angle of insertion of leaf hair, and density of gossypol glands. Hair density and leaf thickness were positively correlated with the population ofB. tabaci, and a positive correlation was obtained between the adult whitefly population and gossypol glands on stem internodes. Cotton genotype USA-22 (sparsely hairy) was found to be more tolerant toB. tabaci than was genotype USA-13 (velvety hairy). The use of thinner and glabrous leaved cotton varieties is suggested to minimize the whitefly menace in cotton.     

Evaluation of the efficiency of alternative two-tier nucleus breeding systems designed to improve meat sheep in Kenya

A deterministic approach was used to genetically and economically evaluate the efficiency of five two‐tier nucleus breeding systems for meat sheep in Kenya. The nucleus breeding systems differed in terms of whether the system was closed or open, in the type of animals that were involved in the movement of genetic superiority and in the number of selection pathways in each system. These systems were compared under four alternative breeding objectives based on monetary genetic gain and profit per ewe. The first objective simulated a situation where the flock size cannot be increased due to non‐feed related constraints (FLOCK). The second specifically assumed that the flock size is restricted due to limited amount of feed resources (FEED). The third and fourth objectives assumed that sheep performed only tangible roles (TR) and both tangible and intangible roles (IR) in the production system respectively. Monetary genetic gains were highest for all objectives in an open nucleus system with a certain proportion of commercial‐born ewes being introduced in the nucleus while at the same time utilizing young rams from the nucleus to breed sires and dams for the nucleus and commercial sector (ONyre). Utilizing young rams in a closed nucleus system for the dissemination of superior genes resulted in higher annual monetary genetic gain than utilization of old rams. Profit per ewe was significantly higher for FLOCK and IR in ONyre. In a closed system that allowed for downward movement of dams from the nucleus to the commercial sector to breed sires and dams, profit per ewe was highest for FEED and TR. The success of a nucleus breeding system should also focus on the profitability and logistics of establishing it. The implication of these results on the choice of two‐tier nucleus breeding systems for the improvement of meat sheep is discussed.     

试论昆虫资源学的理论基础

昆虫资源学是一门既古老又新兴的学科。本文从生物多样性的观点出发,论证了占整个动物界五分之四的昆虫物种多样性,以及昆虫物种多样性的物质表现－丰富的昆虫资源。以生物多样性理论作为昆虫资源学的理论基础,为这一学科注入丰富的内涵和广博的外延。