我国肉羊研究与发展展望

中国养羊业经历了从产毛为主到产肉为主、从散养为主到规模化养殖、从传统养殖到现代化养殖的根本改变,目前中国的养羊业已经进入到了一个全新的时代。文章对中国养羊业进行了简要的回顾,重点对国内肉羊发展和研究内容从遗传育种、饲养管理、繁殖以及疫病防控等方面进行了详细论述,以期为国内同行科研和生产提供参考。     

稻改草后土壤中DDT及其代谢产物的动态变化

用盆栽方法研究了DDT及其主要降解产物在水稻土改种草后土壤中的残留动态，比较了植黑麦草土壤与未植草土壤中DDT残留的差异。盆栽试验设计3种DDT处理浓度，分别为0、0．5、5．0mg kg^-1，每处理4次重复。研究表明，DDT的残留量随着时间的增加而不断减少，且前期降解速率比后期快。在试验的第81天，DDT浓度为0．5、5．0mg kg^-1的植草土壤中，DDT分别减少了27．24％、20．50％。比较植黑麦草和未植黑麦草土壤，p，p′-DDT残留量在试验的16d、32d、64d、81d均出现显著性差异。这可能与植物释放到根际的酶和有机分泌物能有效地促进农药降解有关。同时，DDT的代谢产物DDE随着时间的增加而逐渐增加。     

不同品种花生油脂体粒径电位和蛋白质组成的分析

为了探索不同品种花生油脂体的物理和化学性质差异,以5种（豫花23,豫花27,豫花9719,豫花9830和豫花9502）油脂含量不同的花生品种为原料,采用水剂法提取油脂体,并对提取后油脂体的粒径、ζ电位、氨基酸组成、蛋白质分子量分布进行分析比较。结果表明：提取后,5种花生油脂体粒径间存在一定差异,以豫花9719的粒径较大;花生油脂体均含有油脂体蛋白和贮藏蛋白,但不同品种间存在蛋白质种类的差异;5种花生油脂体在pH值为3.0时ζ电位为正值,在pH值为7.4和pH值为9.0时ζ电位为负值,盐浓度的增加会降低油脂体ζ电位的绝对值;5种花生油脂体的蛋白质均为极性带负电氨基酸质量分数均大于非极性带正电或不带电氨基酸,但氨基酸总量各不相同,以豫花27较低。该研究可为花生油脂体的品质特性研究和应用产品开发提供参考。     

高等农业院校个性化创新型人才培养模式的构建

创新高等农业院校人才培养模式是现代经济、农业发展的必然要求,传统标准单一的人才培养模式已不利于创新型人才的培养和学生个性发展的需要,从探讨构建个性化创新型人才培养模式的内涵出发,论述了高等农业院校构建该模式须把握的原则及基本途径.     

Sap flow of irrigated <Emphasis Type="Italic">Populus alba</Emphasis> var. <Emphasis Type="Italic">pyramidalis</Emphasis> and its relationship with environmental factors and leaf area index in an arid region of Northwest China

Populus alba L. var. pyramidalis Bge. (Populus) is a main tree of the farmland shelter-belt system in the arid region of Northwest China. However, soil moisture cannot satisfy the water requirements of normal Populus growth under local natural conditions, thus studying the transpiration characteristics of irrigated Populus and its relationship with the environmental factors and growth parameters is very important to the growth of the trees in this region. In this study, the sap flow of two irrigated Populus trees was measured during May to September from 2005 to 2008 using the heat-pulse technique. The results show that the maximum and minimum daily sap fluxes in Populus were 15.7–24.0 and 3.0–4.0 L day⁻¹, respectively. And the sum of sap fluxes from June to August accounted for approximately 63–69% of the total sap flux during May to September (almost the whole growing season). The order of the meteorological factors affecting the daily sap flux of Populus was: vapor pressure deficit > solar radiation > mean air temperature > wind speed. Furthermore, a highly linear relationship between the ratio of daily sap flux to the reference evapotranspiration (SF/ET₀) and the amount of soil water in the 0–2.0 m layer was found, indicating that the amount of soil water at this layer was quite important to the growth of Populus in this region. Especially, the amount of soil water in the 0.5–1.0 m soil layer contributed to most of the plant transpiration as the highest coefficient of determination at this layer. Based on the environmental factors and leaf area index influencing sap flux, an empirical transpiration model was constructed to estimate daily transpiration.     

调亏灌溉对温室梨枣树水分利用效率与枣品质的影响

以日光温室生长条件下的6年生矮化密植成龄梨枣树为试材，试验设置试验期间充分供水处理，即对照(T1)，开花—座果期轻度调亏处理(T2)，果实膨大期中度调亏处理(T3)和果实成熟期重度调亏处理(T4)，研究调亏灌溉对梨枣树水分利用效率与枣品质的影响。结果表明：温室内外的参考作物蒸发蒸腾量(ET₀)变化趋势相同，温室内的ET₀值高于外部，二者呈极显著的线性关系，R²值达到0.9501；不同调亏处理均降低了相应调亏时期的土壤水分消耗速率，同时也降低了梨枣树的叶片蒸腾速率和光合速率，开花—座果期和果实成熟期调亏处理提高了叶片水分利用效率，而果实膨大期调亏处理降低了梨枣树的叶片水分利用效率；各调亏处理并未对枣品质的所有指标起到提高和改善作用，成熟期未灌水处理在对平均单果重、枣Vc含量和可溶性蛋白含量产生负面影响很小的情况下，提高了枣的有机酸含量和可溶性固形物含量，总体上改善了枣的品质；综合考虑不同调亏处理对梨枣树各项指标的影响，果实成熟期重度调亏处理在减产不显著条件下，改善了枣的品质，明显提高了水分利用效率，是实施调亏灌溉的最佳阶段。     

ZZWW型四倍体雌蚕减数分裂中的性染色体行为

用过冷却方法处理得到的ZZWW型四倍体雌蚕与ZZ型二倍体交配 ,根据亲、子代个体蚕的标记性状表现及性染色体数观察 ,探讨在减数分裂中ZZWW雌蚕的性染色体的联会、分配的行为方式和概率大小 ,推测ZZWW型四倍体雌蚕在减数分裂中的性染色体联会、分离的可能方式。拟为多倍体诱发机理的解析、交配后代表现的预测提供理论依据和为多倍体研究实用化开发提供有效途径。     

高静压加工对黄桃罐头品质的影响（英）

为拓展非热加工技术在水果罐头加工中应用,以黄桃罐头为试材,研究了高静压加工对黄桃罐头品质的影响。分析了黄桃罐头果肉或汤汁的质地、显微结构、色泽、pH值、可滴定酸和可溶性固形物在加工前后变化,并与传统热加工产品进行比较。结果表明：高静压加工（600 MPa, >5 min）能有效地保持产品质地、显微结构、色泽、pH值、可滴定酸和可溶性固形物,而热加工（90±2°C, 20 min）导致果肉质地软化、显微结构破坏及可溶性固形物增加,严重影响产品品质。同时感官分析表明,与对照相比,高静压加工黄桃罐头除新鲜度及滋味稍差外,其他方面均无明显差别,而热处理黄桃罐头除保持较好色泽与香气外,其他方面均产生劣质的影响。所得研究结果将为高静压技术在水果罐头中工业化应用提供理论依据。     

Response of root morphology and distribution in maize to alternate furrow irrigation

After measuring root morphological indices, such as the length, diameter, volume density, surface area and tip number of both living and dead roots on the ridge and slope under alternate furrow irrigation (AFI) and conventional furrow irrigation (CFI, control treatment) using Minirhizotrons, the responses of root morphology and distribution in maize to AFI were analyzed. Results show that root morphological indices of living or dead roots were lower on the ridge than on the slope under AFI, whereas root morphological indices of living or dead roots were higher on the ridge than on the slope under CFI. Compared to CFI, AFI significantly increased root tip number and surface area of fine roots (with the diameter of ≤2.5 × 10⁻¹ mm) and promoted roots to deeper soil on the slope, and then simulated root water uptake. AFI only decreased the grain yield by 0.9%, but increased water use efficiency on seed yield by 8.3%. Thus AFI promoted root growth and metabolism on the slope, increased the effective absorption area of root system and improved water use efficiency without significant reduction of grain yield.     

Relationship between environmental factor and maximum daily stem shrinkage in apple tree in arid region of northwest China

After measuring maximum daily stem shrinkage (MDS) of irrigated apple tree using dendrometer during the year 2007–2010 in arid region of northwest China, we analyzed the respective relationships between MDS and single plant physiological index and environmental factors to investigate whether MDS can indicate the water status of apple tree and to establish empirical multiple regression equation among MDS and environmental factors. Results show that MDS increased at the beginning and then decreased gradually during whole growing stage. The close relationships between MDS and stem water potential, predawn water potential, stomatal conductance were found, showing that MDS can indicate the water status of mature apple tree. The relationships between MDS and single meteorological variable were significant at the other growth stages except at the bud development and flowering stage, because the canopy structure was not developed, and the order of determination coefficient (r²) over the whole growing stage was maximum vapour pressure deficit > maximum air temperature > net radiation. There were also significant correlations between MDS and soil volumetric water content and reference crop evapotranspiration over the whole growing stage. However, the determination coefficient among MDS and meteorological variables and soil volumetric water content at 0–120 cm depth was higher than those between MDS and single variable. Thus the multiple regression equation among MDS and meteorological variables and soil volumetric water content at 0–120 cm depth can be used to estimate MDS under fully irrigated apple orchard.