水稻中的遗传学知识及试题

水稻是最重要的粮食作物之一，其直接关系到世界一半以上人口的生活质量。水稻的品质与产量是当今水稻研究领域的重点，而对其具决定作用的则是基因。因此关注水稻中的遗传学知识，有助于了解生物科技动态和高中生物遗传学教学，并能达到系统掌握遗传学知识的目的。     

热血玉米情

玉米是世界性的粮食作物，是我国三大粮食作物之一，全国常年种植面积3亿亩。目前．世界玉米的平均单产是520斤，中国是556斤，高出30多斤。但与世界上种植面积大、平均单产高的国家相比，中国的平均单产水平仍然很低。美国的玉米种植是4．5亿亩，1987年平均单产是987．4斤．最高单产是伊利诺州农民赫尔曼华索创造的春玉米3096斤。     

Assessing potential dietary toxicity of heavy metals in selected vegetables and food crops

Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely： inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil （total or bioavailable concentration） that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include： soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity.     

玉米收获技术成果与实践

玉米是我国三大粮食作物,玉米联合收割机的研制生产与推广应用,始终是农机化的一个热点与难点。目前,我国已有60多家企业生产出20余种、80多个机型的联合收割机,但一直没有解决好果穗去除苞皮的关键问题。一、玉米的概况玉米为高杆作物,其形状独特,由茎杆、枝叶、果穗组成,在一年的生长     

“五谷”和“六畜”各指什么

"五谷"是粮食作物的统称。"五谷"之说出现于春秋、战国时期,但解释却有不同,一说是黍、稷、麦、菽、稻;一说是黍、稷、麦、菽、麻。这二种说法的主要区别在于稻麻的有无,之所以出现分歧,是因为当时的作物并不止于五种,"百谷""六谷"和"九谷"说的存在就是一个明证,而各地的作物种类又存在差异所致。"五谷"说之所以盛行,显然是受到     

其实,五谷最养生

人之所以身体好,是因为有"精、气、神"。而这其中,前两者尤为重要——只有精和气充足了之后,人看起来才能有神。精和气其实有一个共同点——它们写起来都有一个"米"字(以前"气"写作繁体时写成"氣")。换句话说:     

学生喜欢上语文综合实践课

这几年,我的学生渐渐爱上了语文综合实践活动课。 一次,我校要求六年级同学对本地粮油作物开展调查。活动中,我让学生先到田间观察了解秋天有哪些粮油作物,然后进行汇报交流。交流课上,一位同学说：“通过调查我了解到,家乡秋天的粮食作物有水稻、粳稻、糯稻、杂交稻、高粱、荞麦、芝麻等作物”。     

浅析入世后承德市种植业结构的调整方向

中国入世后,在解决温饱的基础上,经济效益成为种植业结构调整的主要依据.本文通过对气候条件、经济效益的分析,提出了承德市种植结构的调整方向.北部地区大力发展畜牧业兼营林业;中、南部地区主要发展粮食作物和优质林果.     

天凉好“教”秋,教宝宝认识金秋

秋天金黄的季节,让宝宝观察秋天的景物,感悟大自然变化的美妙。秋天也是收获的季节,让宝宝认识秋天,还可以告诉他一分耕耘一分收获的道理。