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51.
黑杨派南方型无性系引种及选择的研究 总被引:1,自引:1,他引:0
对黑杨派南方型8个无性系的引种试验进行了总结。主要考察了高,径,材积冠幅和抗病能力,应用方差分析和系统聚类分析,将参试无性系划为3个等级,确定了适宜江西省江,湖冲积滩地推广的优良无性系,处于第1级的S1-8和725,其材积生长量分别比1-72杨提高32.6%和30.2%,且有较好的抗病性能,处于第2级的50、710、55/56和S1-6,它们的材积生长量比I-72杨提高17.6% ̄21.7%。 相似文献
52.
选用优质高产红薯品种超然966,研究在湘南气候条件下不同时期、不同密度、不同薯苗稻田种植的产量效应。结果表明,超然966在湘南地区稻田栽培选用上段苗或营养钵苗、密度每公顷5.7万株左右、5月上旬种植可获得较高产量。 相似文献
53.
R. M. Jacobs J. L. Heeney M. A. Godkin K. E. Leslie J. A. Taylor C. Davies V. E. O. Valli 《Veterinary research communications》1991,15(6):463-474
A newly developed milk dot blot test was used to detect anti-bovine leukaemia virus (BLV) antibody in milk samples from 2079 lactating adult cows from among 61 herds. The milk dot blot test was highly repeatable; the concordance rate, compared with the agar gel immunodiffusion test performed on serum, was 83.5%. All herds contained BLV-positive cows; the prevalence rate was 36%. BLV-positive cows tended to come from larger herds and were older and more often later in lactation. Fourteen production and related variables (herd size, age, days open, days in milk, milk somatic cell count, milk, fat, and protein produced in the current lactation, projected production of milk, fat, and protein, and breed class average deviations for milk, fat, and protein) were compared between BLV-positive and BLV-negative cows. Although somatic cell count, milk produced, and projected production of milk and protein were related significantly to BLV status using simple tests of association, once the variables herd size, age and days in milk were controlled, these differences were removed. Further analyses using logistic (outcome: individual cow BLV status) and least-squares regression (outcome:herd proportion of BLV-positive cows) failed to show an association between any of the measured production or related variables and BLV-positivity. We concluded that the effect of BLV on production and related variables in dairy cows was below the sensitivity of our analytical techniques or was non-existent.Abbreviations ABCA
herd average breed class average for milk, fat, and protein production
- AVGAGE
average age of the herd
- ADIM
herd average for days in milk
- AGID
agar gel immunodiffusion
- AVGSCC
herd average milk somatic cell count
- BCA
breed class average, a milk, fat and protein production index calculated by comparing a cow's actual 305-day lactation production to the corresponding BCA standard for the same breed, age, and month of calving
- BLV
bovine leukaemia virus
- CALVINT
calving interval
- COWAGE
cow age
- DBCA
breed class average deviation for milk, fat, and protein production, the difference between an individual cow's BCA and the herd average
- DIM
days in milk
- HS
herd size corresponding to the number of lactating cows in a herd
- LACT
actual amount of milk, fat, and protein produced in a cow's lactation
- ODHIC
Ontario Dairy Herd Improvement Corporation
- PCTPOS
percentage of herd that is BLV-positive
- PROJ
projected 305-day production for milk, fat, and protein by fitting to a standard lactation curve adjusted for days in milk and age at calving
- RHBCA
rolling herd average for breed class average for milk, fat, and protein production, the average for all cows that completed a lactation (cows must have completed a 305-day lactation) during the previous 12 months
- SCC
milk somatic cell count 相似文献
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57.
占补平衡补充耕地按等级折算研究--以南方丘陵山区为例 总被引:3,自引:0,他引:3
占补平衡实现由数量平衡向数量-质量平衡管理的升级,已成为当前土地管理的迫切要求。以南方丘陵山区为例,综合考虑耕地质量的影响因子,筛选台面坡度、海拔高度、有效土层厚度、土壤质地、土壤养分、水源保证率、地下水埋深、排灌设施、道路通达度作为评价指标,应用特尔斐法、层次分析法确定权重,对耕地质量作以评价,确定占、补耕地地块的综合指数。以单位标准粮为桥梁,确定耕地质量数量折算系数.从而实现耕地占补的数量——质量型平衡。 相似文献
58.
p5CS基因在蒙农杂种冰草植株中的表达及耐盐性研究 总被引:1,自引:0,他引:1
为尽快培育出适宜我国干旱荒漠地区大面积推广的耐盐冰草新品种,试验以经PCR和Southern blot杂交检测的含有p5CS基因的蒙农杂种冰草植株为材料,用Northern blot检测目的基因在转化植株中的表达;并用1.5%NaCl盐溶液进行胁迫处理确定转化植株的耐盐性。结果表明:转基因冰草植株与DIG标记探针杂交呈现明显的杂交带;盐胁迫下,游离脯氨酸含量增加较快,质膜透性、丙二醛含量增加较小,SOD活性较高。说明p5CS基因能够在冰草基因组的转录水平上表达,表达植株的耐盐性明显增加。 相似文献
59.
苏南典型地区土壤锌的空间分布特征及其与土壤颗粒组成的关系 总被引:10,自引:5,他引:10
在GIS的支持下,运用地统计学方法研究了苏南典型地区原锡山市土壤全Zn和有效Zn的空间分布特征,并简要分析了土壤全Zn和有效Zn含量与土壤颗粒组成之间的关系。结果表明,研究区域土壤全Zn和有效Zn的空间分布表现出一定的结构性,其空间相关范围分别达到6.6km和7.5km。Kriging插值结果表明,土壤全Zn含量在研究区域东北部最低,东南部相对较高;有效Zn含量与全Zn有着相似的空间分布趋势,受土壤自身特性的影响,其含量在北部地区普遍较低。土壤全Zn和有效Zn含量与土壤粘粒含量之间呈极显著正相关,而与砂粒含量之间呈显著负相关。 相似文献
60.
Daniel S Cooper 《Biological conservation》2002,104(2):205-210
The Puente-Chino Hills, extending west into the highly urbanized Los Angeles Basin, represent one of the largest expanses of lowland habitats in the region. During spring and early summer of 1997 and 1998, birds and vegetation surveys were conducted to clarify the influence of geographical position in the distribution of birds in the hills. Using logistic regression, the inclusion of longitudinal position as a variable is shown to make a statistically significant contribution to bird species presence beyond that of habitat alone for 12 of the 49 most commonly detected species. Species more common than would be expected based on habitat in the east were typical of grassland and open habitats, whereas those more common in the west were characteristic of tall scrub or urban habitats. Thus, species’ distributions in the hills are likely influenced by landscape-scale vegetation patterns and by the aggregate amount of urbanized areas in the west. This emphasizes the importance of using geographical position as a variable when analyzing patterns in bird distribution and siting conservation areas. 相似文献