稻鸭种养模式减肥减药生态效益研究

[目的]研究稻鸭种养模式减肥减药生态效益。[方法]采用随机区组排列,分别设置3个处理:稻鸭种养、不养鸭种稻(CK1)、常规法种稻(CK2),研究不同处理对水稻纹枯病和稻田杂草的防控效果,以及对水稻产量性状、经济效益的影响。[结果]稻鸭种养处理对水稻纹枯病具有显著的防控效果,在分蘖盛期和齐穗期丛发病率分别为22.1%和38.2%;稻鸭种养处理对稻田杂草有较好的控制效果,放鸭后50 d,杂草干重为4.5 g/m2;稻鸭种养处理的理论产量为8 379.5 kg/hm~2,显著高于CK1;稻鸭种养模式的整体利润高于CK1、CK2。[结论]稻鸭种养可促进水稻健壮生长,减少化学肥料和农药的投入,保护生态环境,值得推广。     

典型喀斯特山区无籽刺梨基地土壤质量评价

以贵州省兴仁县回龙镇无籽刺梨种植基地为研究对象,综合考虑表征土壤物理、化学和生物学性质的16个土壤指标,利用数理统计方法确定最小数据集并评价土壤质量,同时根据划分样方所在坡位的不同,对其相应的土壤质量评价结果进行了对比分析。结果表明:(1)研究区土壤质量评价适用的最小数据集(MDS)包括土壤有机质、pH值、全钾、水解氮、真菌和磷酸酶;(2)研究区上坡位、中坡位和下坡位土壤质量属于中等及以下水平,SQI依次为0.544,0.408,0.503;(3)影响该地区土壤质量的重要指标为土壤有机质和土壤真菌数量。     

粗糙集理论在农业生物灾害预测中的应用

借助粗糙集理论,分析了农业生物灾害预测中知识规则获取的方法,有助于提高农业生物灾害预测的效率。     

高效降解纤维素菌株的选育

[目的]筛选纤维素酶活性高且酶活稳定的纤维素降解菌。[方法]以木霉为出发菌株,用紫外线对其进行诱变处理,通过平板初筛和摇瓶复筛筛选出纤维素酶活力高且酶活稳定的优良突变株,然后分别以滤纸、甘蔗渣、麦秆和稻壳为目标降解物对优良突变株进行底物降解试验。[结果]经紫外线诱变、初筛、复筛,共选育出3株纤维素酶活力高且酶活稳定的优良突变株N1、N2、N3,其中N3的产酶活力最高（348 U/ml）,为出发菌株的2.13倍;N3对各种底物的降解效果均优于出发菌株,分别以滤纸、甘蔗渣、麦秆和稻壳为唯一碳源时,其失重率分别为48.68%、41.28%、26.53%和23.47%。[结论]该研究选育出了高效降解纤维素的菌株N3。     

Foraging behavior of heifers with or without social models in an unfamiliar site containing high plant diversity

Grazing behavior, diet selection and weight gain of heifers (with or without social models) were assessed in an unfamiliar site containing high plant diversity. The study was performed within a tropical forest ecosystem containing a mixture of grass forb/herb, shrub and tree species. Ten inexperienced crossbred Bos taurus × Bos indicus heifers (7 ± 1 months old) were randomly assigned to one of two groups: naive or naive + social model (sm) and two experienced heifers (16 months old) were assigned to the second group. Naive heifers were bottle-nursed from days 2 to 90 after birth and began grazing at 1 month of age in tropical grass monocultures, while experienced animals had been foraging in sites containing a high diversity of plant species for 3 months prior to the study. Each group grazed in separate paddocks for a 12-week period during the rainy season, and animals were observed using focal sampling from 7:00 to 19:30 h to assess diet composition based on bite counts. Weight gain was assessed every 14 days. Paddocks contained from 1481 to 1789 kg/ha of herbaceous dry matter, enough to support the heifers throughout the study without affecting diet selection. Shrub and tree cover ranged from 55.2 to 58.4% across treatments. Bites per minute were adjusted to a log-scaled quadratic-plateau model and the curves showed no differences between treatments (P = 0.756). However, diet composition differed between groups (P < 0.001), with naive + sm heifers ingesting a greater proportion of trees (P < 0.001) and shrubs (P = 0.02), while naive heifers ingested more forb/herbs (P = 0.02); no difference in grass consumption was observed (P = 0.92). Heifers in both treatments consumed the same plant species (50 from 26 families). Over time, utilization of several plant species increased or decreased (P < 0.05), eventually leveling off for the remainder of the study. Although differences in diet composition were observed, they did not affect overall weight gain (117 and 113 g/day in the naive and naive + sm groups, respectively; P = 0.913). However, initial post-weaning weight loss was avoided in the naive + sm group. Social learning facilitates a higher use of shrubs and trees in tropical pastures containing a high diversity of plant species with different growth habits. As many plant species have high potential as forage, more effort should be placed on developing mechanisms to increase their dietary inclusion by cattle.     

桶装饮用水质量测评指标权重AHP研究

通过学习层次分析法（AHP）的基本原理和步骤,阅读国内外大量文献,对桶装饮用水质量测评指标权重AHP进行研究,确定桶装饮用水国家标准中那些指标比较重要,哪些影响因素可以引起这些指标超标。     

夏秋季气温对肉牛肥育增重的影响

[目的]为探讨环境温度对肉牛肥育增重效果的影响规律及其程度。[方法]在神木地区夏秋季气温条件下,对秦蒙（秦川牛♂×蒙古牛♀）和丹蒙（丹麦红牛♂×蒙古牛♀）F1二元杂交阉牛与丹秦蒙（丹麦红牛♂×秦蒙牛♀）和利秦蒙（利木赞牛♂×秦蒙牛♀）F1三元杂交阉牛进行肥育对比试验。[结果]表明：试验牛的增重情况与各月份的平均气温有关。[结论]25℃为影响肉牛肥育效果的临界上限温度。     

杨木强化材质量增加率对挥发性有机化合物和甲醛释放的影响1）

通过真空—加压浸渍方式将低相对分子质量脲醛树脂溶液浸渍到杨木中制作强化材,利用GC／MS和紫外分光光度计对杨木强化材释放的挥发性有机化合物（ VOC）和甲醛进行定性和定量分析,探讨质量增加率对处理材VOC和甲醛释放的影响,并分析其作用机理。结果显示：烷烃和醛类化合物是杨木强化材VOC的主要组分,同时检测到少量的萜烯类、酮类和醇类化合物。树脂在木材中的浸渍程度影响杨木强化材VOC及甲醛的释放和力学性能;随着质量增加率的升高,强化材VOC和甲醛释放量呈现先增大而后减小的趋势,释放拐点分别为44．06％和36．35％;力学性能随质量增加率增加而增大,但当质量增加率达到49％以后,抗弯弹性模量和抗弯强度增加幅度不大。因此,在满足材料力学性能基础上,应综合考虑其环保性能和生产成本,从而确定处理材适宜的质量增加率。     

Fusarium oxysporum,F. proliferatum and F. redolens associated with basal rot of onion in Finland

In recent years in Finland, Fusarium infections in onions have increased, both in the field and in storage, and Fusarium species have taken the place of Botrytis as the worst pathogens causing post‐harvest rot of onion. To study Fusarium occurrence, samples were taken from onion sets, harvested onions and also from other plants grown in the onion fields. Isolates of five Fusarium species found in the survey were tested for pathogenicity on onion. Fusarium oxysporum was frequently found in onions and other plants, and, of the isolates tested, 31% caused disease symptoms and 15% caused growth stunting in onion seedlings. Fusarium proliferatum, a species previously not reported in Finland, was also identified. Over 50% of the diseased onion crop samples were infected with F. proliferatum, and all the F. proliferatum isolates tested were pathogenic to onion. Thus, compared to F. oxysporum, F. proliferatum seems to be more aggressive on onion. Also some of the F. redolens isolates were highly virulent, killing onion seedlings. Comparison of the translation elongation factor 1α gene sequences revealed that the majority of the aggressive isolates of F. oxysporum f. sp. cepae group together and are distinct from the other isolates. Incidence and relative proportions of the different Fusarium species differed between the sets and the mature bulbs. More research is required to determine to what extent Fusarium infections spoiling onions originate from infected onion sets rather than the field soil.