不同补光时间和方式对设施大蒜鳞茎膨大和品质的影响

以‘二水早’大蒜为试材,探讨了不同的补光方法对冬季温室栽培大蒜鳞茎膨大及其品质的影响。结果表明：在连续光照达到14 h（9：00-16：00自然光照7 h + 5：30-9：00和16：00-19：30补光7 h）条件下大蒜鳞茎才能显著膨大,非连续光照8 ~ 14 h,即在7 h自然光照条件下,21：00-4：00打破黑暗补光1 ~ 7 h处理均能促进鳞茎膨大,并且鳞茎质量均高于14 h连续光照处理;不同打破黑暗处理之间鳞茎质量无显著差异。随着打破黑暗补光时间的延长,大蒜叶片色素含量,鳞茎中大蒜素、可溶性糖、维生素C、可溶性蛋白、游离氨基酸、总酚含量均呈现出先上升后下降趋势;打破黑暗补光5 h处理的大蒜叶片色素含量,鳞茎中维生素C、可溶性蛋白、游离氨基酸含量最高,分别比连续14 h光照处理提高了30.0%、7.7%、36.2%和25.3%;另外,总酚含量和自由基清除率也是以打破黑暗补光5 h处理最高。因此,从温室大蒜产量考虑,打破黑暗补光1 h处理就能达到较高的鳞茎产量,如果综合考虑产量和品质,则以打破黑暗补光5 h处理最优。     

赤霉素处理打破虎眼万年青休眠的研究

试验以虎眼万年青子鳞茎为材料,采用二因素随机区组设计,对其进行不同温度、不同赤霉素浓度的打破休眠试验,探讨赤霉素和温度对打破虎眼万年青休眠效果,以确定打破虎眼万年青子鳞茎休眠的最适赤霉素浓度和适宜温度。结果表明:赤霉素浓度为100~150 mg/L时打破休眠的效果好并且长势好,低温结合赤霉素处理对打破虎眼万年青休眠的效果更好,能极显著地提高虎眼万年青子鳞茎的出苗率。     

塔里木河下游不同荒漠植被防风阻沙效应

以胡杨、多枝柽柳、铃铛刺和黑刺4种天然荒漠植物为研究对象,对植株单株周围风速以及输沙量的变化进行了观测。结果表明,胡杨对地表风速和输沙量的防阻作用不明显,多枝柽柳、铃铛刺和黑刺灌丛对地表风速和输沙量的影响较明显;不同灌丛的迎风面2倍树高( TH)处的风速大于迎风面1TH处风速,输沙量大小与风速大小成正比;灌丛两侧1TH处的风速与输沙量大于迎风面1TH和2TH处风速与输沙量;背风面1TH处的风速最小,背风面风速达到一定距离后渐渐恢复原来的风速;背风面输沙量1TH处最小,距离越远越大;这4种植物的防风效益依次为多枝柽柳B1>胡杨A1>多枝柽柳B2>铃铛刺C1>黑刺D1>铃铛刺C2>黑刺D2>胡杨A2。     

凡纳滨对虾总RNA完整性的正确评估

凝胶电泳技术通常被用于总RNA完整性检测,一般认为28S和18S rRNA条带亮度的比值大于等于2表示总RNA完整性良好,该比值越小表明总RNA降解越严重。为了检测这一标准在水产虾蟹类中是否继续适用,分别对凡纳滨对虾rRNA和mRNA的完整性进行了分析。用TRIzol分离纯化的凡纳滨对虾总RNA经凝胶电泳检测,发现其28S:18S rRNA的比值远小于2;但是以同样的总RNA为模板进行RT-PCR,能顺利扩增出长约1 100 bp的ACT和eEF1A基因序列。进一步的3':5'分析显示这2个内参基因mRNA的3':5' ratio分别为2.79和1.53,直接表明被测mRNA完整性良好。因此,凝胶电泳低估了水产虾蟹类总RNA的完整性,建议采用3':5'分析技术对水产虾蟹类总RNA完整性进行检测。     

Asymmetric Price Transmission and Structural Breaks in the Relationship between Costa Rican Markets of Livestock Cattle,Beef and Milk

The vertical price transmission is generally considered as the relationship between two markets of the same production chain However, we can expand this concept to another relation which has not been deeply investigated： the joint products. They are the products which are produced in a single production process, but not correspond to the same chain. An especial case is the beef and milk markets in Costa Rica. Even if these products usually correspond to disconnect chains, in Costa Rica farms make use of cattle to produce both meat and milk. The cointegration framework is applied in order to indentify the price transmission among these markets. In addition, the asymmetric behavior and structural breaks are taken into account. Price transmission between each market pair was found. First, the cattle prices adjust in the milk-cattle relationship, second, beef meat prices adjust in the cattle-beef meat and in the milk - beef meat relationship. Finally, the equations allowing for structural breaks affect the estimates in the following three ways： after the break the elasticities became higher than 1, there is more evidence of cointegration, and the adjustment coefficients are significant only when a change in the long run is allowed.     

Vorfruchtwirkungen verschiedener Blattfrüchte auf Winterweizen und Einfluß von Anbaumaßnahmen

Effects of preceding "break crops" on winter wheat and influence of cultural practices
Between 1979—83 there was tested the effect of 5 "break crops" (biennial alfalfa, clover-grass, faba bean, winter-rape, silomaize) on succeeding winter wheat and the interaction with changed cultural practices such as N-fertilization and conventional or reduced primary tillage (plough ↔ rotary tiller).
After the break crops wheat yield decreased within a range of 4 dt/ha as follows: alfalfa → beans → rape/ clover-grass/maize. Raising N-fertilization hardly allowed to improve the value of the break crops; most likely that of maize and with rotavating. Adaption of N-dressings promised greater influence.
The manner of primary tillage exerted stronger influence on the yield than the level of N-fertilization. Concerning long-term yield the rotary tiller equaled the plough after 4 break crops; after faba bean it was superior. Increasing N-fertilization tendentially favoured the rotary tiller after bean, rape and maize. Using the rotary tiller, at beginning of growth there may be calculated on 15 % higher NO₃-values and/or higher N-mineralization or N-transformation.
Eyespot disease could not be prevented sufficiently and purposefully by an other break crop, N-fertilization or primary tillage. Recurrent rotavating suppressed weed less than ploughing.     

玉米秸破碎力学特性的研究

通过对玉米秸破碎时的力学特性的实验研究,得出了影响其破碎的主要因素为含水率、生长部位和茎节状况,为秸秆加工设备的研制做了理论上的准备。     

Rootstock effect on growth of apple scions with different growth habits

Apple scions with diverse growth habits were grafted on various size-controlling rootstocks and morphological characteristics were measured after 6 years of growth in the field. Scion had more influence than rootstock on monthly growth rate. Across all rootstocks, scions with spreading growth habits grew rapidly in April and May and achieved most seasonal growth earlier than scions with upright growth habits that grew slowly early in the season. In all growth habits and rootstocks, growth rate slowed appreciably but did not cease by August and growth did not terminate earlier for any one scion–rootstock combination. Across all scions, the dwarfing rootstock, M.9, consistently had the lowest and seedling rootstock had the greatest tree height and trunk diameter. However, no one size-controlling rootstock consistently influenced dates of bud break and full bloom, shoot elongation rate, or duration of growth. Tree growth form was not fundamentally affected by rootstock. Significant interactions indicated that effects of size-controlling rootstock on components of shoot growth will vary with apple tree growth habit. These effects on phenology and development can be significant to growers and may assist breeders in developing new apple cultivars.     

山西省贫困地区经济发展的新出路——以山西省翼城县青城村发展旅游业为例

本文以山西省贫困地区青城村为例,在实地考察的基础上,通过对其经济贫困状况及发展旅游业的SWOT分析,尝试性地提出了通过发展绿色旅游和红色旅游产业促进其经济快速发展、脱离贫困状态的新途径,并针对SWOT的分析,提出了促进青城村旅游业发展的对策及建议.     

台湾桂竹笋─幼竹生长规律研究

台湾桂竹笋─幼竹生长规律研究黄克福，马炳杨（福建林学院林学系，福建南平３５３００１）（莆田县林业局，福建莆田３５１１００）摘要３０个样地材料分析结果表明：台湾桂竹出笋起始期为４月上旬或中旬，持续出笋２０～３０天；退笋率为２３％～３０％，成竹率较高；在...