美洲黑杨新无性系生根性状的遗传分析

对12个美洲黑杨无性系生根性状遗传变异的研究表明,不同无性系在最早生根时间、主根总数及主根总长等方面均存在极显著差异。水培不同时期主根总数、主根总长的广义遗传力在0.657 0~0.691 1、0.617 5~0.785 9之间,表明这两个生根性状在无性系间具有稳定的遗传变异,且受中等至强度遗传控制,具有较大的选择潜力。采用50~150 mg/L ABT溶液预处理对各无性系诱导根平均根数和平均长度有不同程度的促进作用,且以50 mg/L ABT溶液预处理后长势最好。     

海南岛清澜港红树树种适应生境能力与水平分布*

红树植物的器官形态变异反映了它们对于不同潮间带生境的适应能力，灰色聚类分析结果表明杯萼海桑、海桑、正红树属于适应潮间带生境能力强的种类，木榄、海莲属于适应潮间带生境弱的种类。适应能力强者在低、中潮滩组建群落，适应能力低者在高、中潮滩组建群落。随潮间带淤积升高，适应能力强者不断向外占领裸滩，适应能力弱者不断侵入适应能力强者的迹地。     

竹炭吸湿性的初步研究

选用箱式电阻炉和土窑烧制的竹炭,在不同温度和湿度条件下进行竹炭吸湿性变化的试验.结果表明:(1)500℃、600℃、800℃和土窑(二)的竹炭其吸湿性与温湿度有较显著关系;而700℃竹炭和土窑(一)竹炭的吸湿性与温湿度之间没有显著关系.在一定温湿度范围内,湿度对竹炭吸湿性的影响比温度显著.(2)不同炭化温度之间的竹炭其吸湿性不同.800℃的竹炭其吸湿性最大,其值为11.5%,500℃的竹炭最小,其值为8.6%;600℃的竹炭8.8%;700℃的竹炭为11.3%.(3)不同土窑的竹炭其吸湿性有显著差异.土窑(一)和土窑(二)的竹炭吸湿值分别为9.8%和6.4%.     

Petroleum flotation technique upgrades the germinability of <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> seed lots

The germination of Casuarina equisetifolia Forst seed lots is low (40–50%) even when freshly collected. This study aimed at upgrading the germination performance by removing non-germinable seeds using petroleum flotation technique. Seeds collected from 19 individual trees in seedling seed orchards in India were assessed using X-ray to determine the proportion of different seed lot fractions. The feasibility of petroleum ether as a separation medium was tested. Morphological characters of floating and sunken seeds were further studied using image analysis technique to examine their effects on the separation efficiency. The X-ray analysis revealed a large quantity of shrivelled, empty and insect-damaged seeds, altogether accounting 50%, which were the causes of low percentage germination of un-graded seed lots (48%). Petroleum flotation resulted in 90% germination in the sunken fraction and 4% in the floating fraction. The separation was distinct for most seed lots, except few seed lots that had relatively low germination in the sunken fractions and more than 10% germination in the floating fractions. As a whole, petroleum flotation appears to be a feasible technique to upgrade the germination of C. equisetifolia seed lots, and its efficacy is influenced by wing surface area, seed density and wing quotient of filled and empty seeds.     

观赏槭树的苗期试验初报

观赏槭树育苗试验表明,不同树种、种源间种实发芽率差异较大。发芽率较高的种类有樟叶槭(92%)、鸡爪槭(90%)、三角枫(90%),其次是复叶槭(85%)、红花槭(82%)、橄榄槭(76%)和元宝槭(75%);茶条槭、五角槭、罗浮槭发芽率均小于70%。1年生苗高生长量以复叶槭最大(113.98 cm),其次是三角枫(101.21 cm);樟叶槭和鸡爪槭1年生苗生长量中等,当年生长量分别为62.43 cm和71.74 cm;罗浮槭、青榨槭和橄榄槭1年生苗高生长量较小。季节生长节律有3种类型:橄榄槭、鸡爪槭、元宝槭、茶条槭等几种槭树表现为第1类型(前期生长型),即5月前苗木缓慢生长,6~7月进入速生期,7月以后苗木渐渐停止生长,速生期较短。复叶槭和青榨槭表现为第2种类型:1年生苗全年高生长有2次高峰,出现在6月和9月;樟叶槭和三角枫季节生长节律表现为第3种类型:5月生长缓慢,6月生长开始加快进入速生期,一直持续到8月底,速生期长。三角枫、橄榄槭、鸡爪槭、元宝槭、茶条槭、复叶槭和青榨槭等几种槭树表现出较强的抗寒性,樟叶槭和罗浮槭抗寒性较差。     

如何在和谐社会中培养优秀的音乐教育人才

未来社会需要高素质的、德才兼备的、具有宽广知识、一专多能的音乐教育人才.在提高专业技能知识的同时,培养学生综合素质,是当前和谐社会中培养高素质人才的关键.     

Morphological plasticity of cotton roots in response to interspecific competition with pecan in an alleycropping system in the southern United States

A study was conducted in northwest Florida, USA, to investigate root development and morphology of cotton (Gossypium hirsutum L.) under pecan (Carya illinoensis K. Koch) trees in an alleycropping experiment. Root:shoot ratio, root biomass, total root length and root length density were examined under three treatments: (1) barrier (separating belowground interspecific competition by trenching to a depth of 120 cm and installing polyethylene barrier), (2) non-barrier (root systems were free to interact), and (3) monoculture of cotton (without above and belowground interspecific competition with trees). Results indicated that plants in the barrier and non-barrier treatments had lower root:shoot ratios compared to the monoculture treatment. Belowground competition for resources between pecan and cotton in the non-barrier treatment resulted in 25 and 33% reduction of total root length (359 cm) when compared to that of the barrier (477 cm) and monoculture (539 cm) treatments, respectively. The non-barrier plants also exhibited the lowest root length density. Specific root length was highest for the monoculture (179 cm g⁻¹) and lowest for the non-barrier treatment (146 cm g⁻¹) with the barrier treatment being intermediate (165 cm g⁻¹). Interspecific competition with pecan significantly altered root development and morphology of cotton plants. Research in agroforestry should take into account the developmental differences in root systems of the associated crop species so that better models incorporating nutrient and water uptake can be developed.     

生产实践性教学在农业机械学中的必要性

农业机械学的实践性教学从实际动手出发,培养学生在复杂多变的实际工作中解决工程实际问题的能力和意识。为此,总结生产实习的收获,分析实践性教学环节在农业机械学专业课学习中的地位和作用,得出实践性教学是培养现代化工程师的有效途径。     

创新教学方法培养创新人才

培养具有创新能力的优秀人才是对高等教育的本质要求：学生创新能力的培养具有多种方式，其中，创新教学方法是培养创新人才的一种有效途径。我们在农业工程类专业课程教学中，积极进行教学方法的创新，鼓励学生进行自主性教学活动，提高了学生的创新能力，收到了很好效果。     

《工程图学》与素质教育

《工程图学》以“图”为核心,图必构物,源于工程。其学习过程由直觉到抽象、由感性到理性、由理性到实践,是“素质教育”增长点、“多种思维”交错点、“创新思维”生长点、“创造智能”发展点、“完善人格”着力点及“创新能力”持续点,对培养发展学生的完善人格和创新能力,具有其他学科不可替代的作用。