山羊卵母细胞无血清体外成熟培养

为研究无血清培养系统对山羊卵母细胞体外成熟及孤雌激活胚胎早期发育力的影响,分别以0.3%牛血清蛋白(BSA)(mV)、1%聚乙烯醇(PVA)(mV)和1%胰岛素转铁蛋白亚硒酸钠(ITS)(VV)代替成熟培养液中胎牛血清(FBS),以添加5?S的OM为对照组,对来源于屠宰场的卵巢卵母细胞复合体(COCs)进行体外培养。成熟率PVA添加组(50.00%)显著低于FBS组(83.23%)(P<0.01)、BSA组(71.19%)和ITS组(76.79%),与FBS组无显著差异(P>0.05);成熟卵母细胞用离子霉素联合6-DMAP激活,在SOFaa中进行孤雌胚培养,BSA、PVA、ITS及FBS各组的卵裂率依次为61.90%、46.97%、79.07%和83.58%,囊胚率分别为25.00%、19.70%、55.81%和60.45%。结果表明:在OM基础培养液中添加BSA或PVA,卵母细胞的成熟率明显低于添加FBS,且卵裂率和囊胚发育率也低于对照组(P<0.05或P<0.01);添加ITS,卵母细胞成熟率虽低于对照组,但孤雌胚卵裂率和囊胚发育率与对照组接近(P>0.05)。表明以ITS代替FBS,可用于山羊卵母细胞体外成熟培养。     

空间变异在土壤性质长期定位观测及取样中的应用

通过对中国科学院沈阳生态实验站30m×42m样地进行网格法分层取样,采用经典统计学与地统计学相结合的方法,以土壤pH和有机碳(TOC)为例,探讨了空间变异在土壤性质定位试验及取样中的应用。结果表明,49对样本的pH和TOC变异系数均小于10%,变量在0~10cm和10~20cm两个层次的基本统计数值基本接近,最佳理论模型的参数显示各变量空间变异主要受结构性因素的影响,且以135°方向的变异为主;相对误差为10%时采集6个和10个土样可分别达到95%和99%的置信水平,结合空间分布格局可以确定更为精确的取样方案;综合分析表明待选样地可以作为土壤性质长期定位观测试验用地。     

流域侵蚀强度空间分异及动态变化模拟研究

流域侵蚀强度空间分异是小流域泥沙来源研究的重要内容之一。该文以小流域模型模拟试验为基础，利用人工模拟降雨、近景摄影测量和GIS技术，对流域模型不同空间部位的侵蚀强度及其随流域所处发育阶段的动态变化进行了研究。研究结果表明：依据次降雨相对侵蚀模数REM将历经25场模拟降雨的小流域模型发育过程划分为初期时段、活跃时段和稳定时段。沟谷侵蚀强度在整个流域模型发育过程中一直大于坡面；在流域发育初期时段至活跃时段前期，主沟侵蚀强度大于支沟，流域下部侵蚀强度大于中部和上部；在流域发育活跃时段后期，主沟侵蚀强度低于支沟，流域中部和下部侵蚀强度快速增长并达到峰值；在稳定期时段，主沟和支沟侵蚀强度变化趋于同步，流域上部的侵蚀强度高于中部和下部。流域侵蚀强度的时空分布特征对于小流域水土流失综合治理具有科学指导意义。     

Release and activity of allelochemicals from allelopathic rice seedlings

3-Isopropyl-5-acetoxycyclohexene-2-one-1 (1), momilactone B (2), and 5,7,4'-trihydroxy-3',5'-dimethoxyflavone (3) were isolated and identified from an allelopathic rice accession PI312777. These three compounds at low concentrations could inhibit the growth of weeds Echinochloa crusgalli and Cyperus difformis associated with rice, especially mixtures of the compounds had stronger inhibitory activity than did individual compounds. Studies with hydroponic culture, continuous root exudates trapping system (CRETS), and direct resin adsorption methods showed that a total of 7.6 n moles 1, 2, and 3 were exuded from living roots of each seedling into the environment at 10 days after seedlings were transplanted. Furthermore, 1, 2, and 3 were found in the soil growing PI312777 seedlings at day 15 after seedlings emergence and reached a total of 39.5 microg/g soil at day 30. The results indicated that PI 312777 seedlings could release sufficient quantities of 1, 2, and 3 into the environment to act as allelochemicals inhibiting the growth of associated weeds. Investigations on the distribution of 1, 2, and 3 in PI 312777 plant, and its root exudates showed that the levels of 1, 2, and 3 were significantly higher in the shoots and root exudates than in the roots, and only trace 1 was observed in the roots. The results suggest that the roots of rice seedlings are not major site of synthesis or accumulation 1, 2, and 3, but a pathway for their release into the environment. The levels of 1, 2, and 3 in the root exudates were over 2-folds higher under direct resin adsorption than under hydroponic culture and CRETS, and hence, it is the preferred method to collect and identify active allelochemicals in rice exudates in future studies on rice allelopathy.     

Fractal features of soil particle size distribution and the implication for indicating desertification

Some of the effects of land desertification on soil properties are manifested by the coarsening of the soil particlesize distribution (PSD) and the losses in organic C and nutrients. The changes and characteristics of PSD and selected chemical properties in soils at the 0-15 cm plough layer from different degrees of desertified croplands are analyzed in the semiarid Horqin Sandy Land, northern China. The fractal dimension of the PSD is emanated to characterize the patterns of PSD. The relationships between the fractal dimension of the PSD and selected soil properties are discussed. The results show that: (1) in the transformation from potential desertified cropland to extremely desertified cropland, the sand content at the 0-15 cm soil increased from 69% to 93%, organic C and total N contents decreased by 65% and 69%, respectively; (2) the fractal dimension of PSD ranged from 2.179 to 2.611, the more the contents of sand, the lower the fractal dimension and the higher the desertified degree of farmland. In the desertification process within the studied area, the mean fractal dimension decreased from 2.555 for the potential desertified soils to 2.298 for extremely desertified soils; (3) there existed considerable linear relationships between fractal dimension and soil properties. It was shown that fractal dimensions of PSD are useful parameters able to monitor soil degradation and to estimate the degree of soil desertification.     

机械化整秆覆盖膜侧沟播保护性耕作技术的试验研究

中国黄土高原地区由于干旱、无霜期短而严重影响春玉米产量,该文研究应用整秆覆盖免耕膜侧播种的耕作模式,在冬闲期采用机械将玉米秸秆整秆压倒覆盖免耕,在种植期带状起垄覆膜,膜侧播种,行间秸秆覆盖,集储水、保墒、增高地温于一体。结果表明,该技术与传统的露地深翻模式相比,具有明显的储水、保墒、增高地温和提高玉米产量的效果。     

自控变频调速式灌溉水注肥装置的研究

为现代农业节水灌溉与精准施肥所需的配套注肥装置的开发,研究采用输液泵将肥料原液和酸碱调节液强行注入灌溉管网,并与灌溉水按比例混合获得一定浓度和酸碱度(EC & pH)的灌溉液。灌溉液浓度和酸碱度通过EC传感器和pH传感器检测并反馈PLC控制系统,通过变频调速进行EC值与pH值动态调节,实现节水灌溉系统的精准施肥灌溉。采用自控变频调速技术的灌溉水注肥装置经过实际运行,完全满足设计要求,可实现灌溉液的正常输送和EC值与pH的动态调节。特别是射流自吸泵变频调速技术的实现,不仅有效实现了灌溉液浓度（EC值）的动态调节,同时降低了设备成本,完全可用于节水灌溉注肥装置的开发。     

南方温室不同时段遮阳降温效果及对甜椒生长发育和产量的影响

该试验主要研究了南方温室中一天内不同时段遮阳降温效果及对甜椒生长发育及产量的影响.结果表明,各处理遮阳降温效果显著,最大降温幅度可达7℃,但不同时段及不同时间长度遮阳降温效果差异不大,有效降温和有效降温时间段基本是一致的.不同时段遮阳降温对甜椒生长发育及产量的影响差异较大,在中午1200至下午1500时间段进行遮光降温,植株净光合速率最高,叶片叶绿素含量增加,促进生殖生长,提高坐果率,甜椒前期产量和总产量显著提高.随着遮阳降温时间的段前移和延长,植株表现徒长,叶绿素含量、净光合速率及坐果率降低,产量明显降低.     

非统计理论在灰色建模中的应用

为了解决灰色建模过程中利用残差模型来修正原灰色模型的繁琐工作,提出利用稳健估计理论对灰色建模的数据序列进行分析、筛选,找出数据列中存在的不确定信息,并达到直接建立灰色模型的目的。针对数据中存在不确定信息的实际情况,利用非统计理论对所研究的数据序列进行分析,对不确定信息中是否含有误差有一个确切的结论。进而找到一个比较方便而准确的建立灰色模型的方法。     

“生产－生活－生态”农业工程技术集成模式的研究

发展现代农业促进新农村建设已成为中国新时期“三农”工作的中长期战略重点和指导方针。“生产-生活-生态”的研究就是以生产提高为主体、以生态化运行为要求、以生活改善为目标，通过分析新农村建设的功能目标、现代农业工程技术状况、技术集成边界条件特点等，获得5种典型的“生产-生活-生态”技术集成模式。这些模式的应用，可为新农村建设中实现完整、科学的“生产-生活-生态”产业循环提供理论依据和示范模式，不仅有较强的现实意义和可操作性，也将在新农村建设的推进中显示出重要的长远意义。