普通株型玉米不同密度下种植模式的研究     

王斌  李宏  李爱军  董红芬  王召菊 《勤云标准版测试》2009,29(14)

选择普通株型的玉米品种农大108,在设置固定的3种密度前提下,通过调整株行距种植比例,探索不同密度产量水平的变化规律.试验结果表明:高密度的产量较低密度下有较大的增产,大小行种植对于普通株型的农大108来说,产量没有明显的变化,产量与密度有密切相关性,与种植模式没有太大的关系.  相似文献   

母猪倒骑式按摩输精法的应用效果研究     

张士海  巴良兴  崔艳  孟克杰  张寅屏  史文清 《猪业科学》2021,38(5):112-114

研究的目的是验证猪常规人工授精中倒骑式按摩法输精方法的效果，分析配种后受胎率与产仔数。在断奶发情的实验母猪发情鉴定表现定立表现时，采用倒骑式按摩法输精技术，实施子宫颈人工授精。按摩母猪乳房时间为30～ 60 s。输精完成后继续倒骑60 s。试验组与对照组相比，母猪发情表现主要集中在72 h到96 h之间，母猪断奶处理120 h内发情的母猪情况水平一致；试验组受胎率提高8.56个百分点，与对照组差异显著（P<0.05）；两组的窝产仔数、初生重差异不显著（P>0.05）；实验组的窝平均活仔数提高1.2头，断奶重提高3.55%，与对照组差异极显著（P<0.01）。试验表明，倒骑式按摩法人工输精技术能够获得较高的受胎率与活仔数，仔猪增重较好。  相似文献   

孵化季节对阿根廷滑柔鱼生长发育的影响   总被引：2，自引：2，他引：0  

林东明  韩飞  朱凯  陆化杰  陈新军 《上海海洋大学学报》2020,29(3):374-384

头足类属种具有寿命短、终生一次繁殖产卵的生长发育特性,这些特性往往与仔鱼的孵化季节密切相关且影响世代的繁衍交替。为此,基于日龄判读和孵化月份推算,研究阿根廷滑柔鱼性腺成熟个体大小与孵化月份的效应关系,分析孵化月份对其生长发育的影响。结果显示,阿根廷滑柔鱼性腺成熟雌性个体的胴长为(246.59±40.36) mm,日龄为(293.79±32.68) d,平均生长速率为(0.84±0.11) mm/d;成熟雄性个体的胴长为(222.82±28.60) mm,日龄为(299.24±32.97) d,平均生长速率为(0.75±0.08) mm/d。性腺成熟个体的孵化月份为3—8月。随着孵化月份推移,性腺成熟个体的日龄显著降低,而平均生长速率逐渐增加;性腺成熟个体胴长大小与其平均生长速率密切相关;孵化月份对雌雄个体生长发育的影响效应具有一致性,较早孵化的个体生长速率较慢,而晚孵化的个体生长速率较快。研究表明,阿根廷滑柔鱼的生长发育与孵化季节密切相关,不同孵化月份的个体通过调节生长速率以达到性腺成熟胴长。  相似文献   

Size- and leaf age-dependent effects on the photosynthetic and physiological responses of Artemisia ordosica to drought stress     

WANG Chunyuan 《干旱区科学》2021,13(7):744-758

Drought is one of the most significant natural disasters in the arid and semi-arid areas of China. Populations or plant organs often differ in their responses to drought and other adversities at different growth stages. At present, little is known about the size- and leaf age-dependent differences in the mechanisms of shrub-related drought resistance in the deserts of China. Here, we evaluated the photosynthetic and physiological responses of Artemisia ordosica Krasch. to drought stress using a field experiment in Mu Us Sandy Land, Ningxia Hui Autonomous Region, China in 2018. Rainfall was manipulated by installing outdoor shelters, with four rainfall treatments applied to 12 plots (5 m×5 m). There were four rainfall levels, including a control and rainfall reductions of 30%, 50% and 70%, each with three replications. Taking individual crown size as the dividing basis, we measured the responses of A. ordosica photosynthetic and physiological responses to drought at different growth stages, i.e., large-sized (>0.5 m²) and small-sized (≤0.5 m²) plants. The leaves of A. ordosica were divided into old leaves and young leaves for separate measurement. Results showed that: (1) under drought stress, the transfer efficiency of light energy captured by antenna pigments to the photosystem II (PSII) reaction center decreased, and the heat dissipation capacity increased simultaneously. To resist the photosynthetic system damage caused by drought, A. ordosica enhanced its free radical scavenging capacity by activating its antioxidant enzyme system; and (2) growth stage and leaf age had effects on the reaction of the photosynthetic system to drought. Small A. ordosica plants could not withstand severe drought stress (70% rainfall reduction), whereas large A. ordosica individuals could absorb deep soil water to ensure their survival in severe drought stressed condition. Under 30% and 50% rainfall reduction conditions, young leaves had a greater ability to resist drought than old leaves, whereas the latter were more resistant to severe drought stress. The response of A. ordosica photosynthetic system reflected the trade-off at different growth stages and leaf ages of photosynthetic production under different degrees of drought. This study provides a more comprehensive and systematic perspective for understanding the drought resistance mechanisms of desert plants.  相似文献   

中国水牛乳蛋白基因型与酪蛋白胶束粒度的关联研究     

陈晨  赵烜影  郭鸰  李玲  刘建新  任大喜 《中国畜牧杂志》2020,(1):70-76

本研究旨在分析中国水牛乳蛋白各亚型与乳蛋白粒径的关联。采用反向高效液相色谱法对160头泌乳中期的水牛进行多态性测定,并利用激光粒度仪分析水牛乳蛋白的粒径。结果显示:αs1-酪蛋白(αs1-CN)、β-酪蛋白(β-CN)和α-乳白蛋白(α-LA)存在A型和B型2种基因型,κ-酪蛋白(κ-CN)有A型、B型、C型和D型4种基因型,αs2-酪蛋白(αs2-CN)和β-乳球蛋白(β-LG)没有发现多态性。κ-CN和αs1-CN各亚型在乳蛋白面积平均径(D[3,2])上有显著差异,筛选出的6种αs1-β-κ-CN复合基因型在乳蛋白面积平均径(D[3,2])以及中位径(D50)上差异显著。综上,水牛αs1-β-κ-CN复合基因为AB-BB-AB型以及κ-CN的C等位基因均与乳蛋白粒度存在显著关联。  相似文献   

硫肥对小麦籽粒淀粉粒度分布的影响     

杨兵兵 《现代农业科技》2023,(18)

摘要：为研究施硫对小麦胚乳淀粉粒分布特征的调控效应，以小麦品种烟农19和山农22为材料，研究不同氮素水平条件下，硫肥对胚乳淀粉粒分布特征的影响。结果表明，不同处理小麦籽粒淀粉粒体积、表面积、数目分布分别呈双峰、三峰和单峰曲线分布。在施纯氮120 kg/hm2（低氮水平）条件下下，随施硫量的增加，籽粒B型淀粉粒体积百分比显著降低，A型淀粉粒体积百分比显著升高。在施纯氮240 kg/hm2（适氮水平）条件下，随施硫量的增加，籽粒B型淀粉粒体积百分比先升高后降低，A型淀粉粒体积百分比先降低后升高。在施纯氮120 kg/hm2条件下下，随施硫量的增加，籽粒3.6μm～10μm淀粉粒数目百分比逐渐降低。在施纯氮240 kg/hm2条件下，随施硫量的增加，籽粒3.6μm～10μm淀粉粒数目百分比逐渐提高，S9处理效果下降。在施纯氮120 kg/hm2条件下，随施硫量的提高，小麦籽粒B型淀粉粒的表面积百分比显著降低，A型淀粉粒表面积百分比显著增加；在施纯氮240 kg/hm2条件下，随施硫量的提高，小麦籽粒B型淀粉粒表面积百分比逐渐增加，A型淀粉粒表面积百分比逐渐降低，高硫S9处理施用效果下降。可见，在低氮水平下施硫有利于淀粉粒体积的增大；在适宜氮素水平下施硫有利于3.6-10 μm淀粉粒数目的增加，但过量硫肥施用效果下降。  相似文献   

Dietary overlap and selectivity among silver carp and two native filter feeders in the Wabash River          下载免费PDF全文

Mario Minder  Mark Pyron 《Ecology of Freshwater Fish》2018,27(1):506-512

Silver carp (Hypophthalmichthys molitrix) are a potential threat to native filter feeders and larval fish due to dietary overlap. To test for dietary overlap and selectivity, we collected diet samples from invasive silver carp and two native filter feeders (gizzard shad Dorosoma cepedianum and bigmouth buffalo Ictiobus cyprinellus), and river plankton samples at three sites on the Wabash River during the spring and summer of 2015. Contents of diet items were identified to major group and quantified. Diet proportions were compared among seasons, sites and species. Diet selectivity was calculated using the Manly–Chesson diet selectivity index. The results of our diet analysis showed that silver carp had significantly dissimilar diets among seasons and displayed dietary overlap with native fishes. We did not find a significant difference among sample sites. While silver carp diets overlapped with native fishes, the impact of this possible source of competition requires further study to confirm impacts on native fish abundances and body conditions.  相似文献   

Morphometric analysis of cervical vertebrae in some marine and land mammals     

Burin Boonsri  Korakot Nganvongpanit  Kittisak Buddhachat  Veerasak Punyapornwithaya  Piyamat Kongtueng  Patcharaporn Kaewmong  Kongkiat Kittiwattanawong 《Anatomia, histologia, embryologia》2021,50(5):812-825

Bones or skeletal remains can be used to answer a number of questions related to species, sex, age or cause of death. However, studies involving vertebrae have been limited as most were performed on skulls or long bones. Here, we have stated the hypothesis that the morphometry of cervical vertebrae can be used for species identification and body size estimation among marine and land mammals. The cervical vertebrae from eight and 14 species of marine and land mammals were used to collect morphometric data. Cluster dendrogram, principal component analysis, discriminant analysis and linear regression were used to analyse the data. The results indicate that, based on an index of C4 to C7, there were 13 out of 22 species for which identity could be correctly predicted in 100% of the cases. The correlations between cervical vertebrae parameters (height, width and length of centrum) in marine (average R^2 = 0.87, p < .01) and land (average R^2 = 0.51, p < .01) mammals were observed. These results indicate that vertebral morphometrics could be used for species prediction and verification of body weight in both marine and land mammals.  相似文献   

Settling velocity and particle size bioengineering parameters gathered from solids generated by wild-caught premature punctuated snake-eels (Ophichthus remiger) reared in a marine prototype recirculating aquaculture system     

《Aquacultural Engineering》2020

This research reveals the applied engineering basis for determining the particle size and settling velocity distributions of solids generated while rearing wild-caught premature punctuated snake-eels (Ophichthus remiger) in a prototype recirculating aquacultural system. Settled solids were sampled from the bottom of the rearing tanks, and suspended solids were sampled before filtration within the drum filter and analyzed to characterize their settling velocity and particle size properties. These particle properties are considered bioengineering parameters since they will provide biological information to improve engineering solutions for RAS solids removal processes. The average settling velocity for the settleable solids in the rearing tanks was 2.89 ± 0.02 cm s⁻¹, and the average particle size ranged between 7.32 ± 3.41 and 19.44 ± 8.58 mm. Suspended solids within the drum filters before filtration had an average settling velocity of 0.35 ± 0.11 cm s⁻¹ and it was found that 69.93 % of the particles size was greater than 200 μm, 15.40 % were within the range of 120 μm and 90 μm sizes, and 6.53 % were between 70 μm and 40 μm sizes. The particle physical properties, settling curves, and particle sizes curves obtained from this experience represent valuable information to be used to improve engineering design of solids handling mechanisms, especially in marine land-based systems, and in this case, applied for rearing wild-caught punctuated snake-eels. The present investigation constitutes an advance in the knowledge of applied engineering to the design of a marine aquaculture fattening operation targeted to feed up wild-caught premature punctuated snake-eels to the point of sale or trade.  相似文献   

Cross-tolerance for drought,heat and salinity stresses in chickpea (Cicer arietinum L.)     

Raju Pushpavalli  Jens D. Berger  Neil C. Turner  Kadambot H. M. Siddique  Timothy D. Colmer  Vincent Vadez 《Journal of Agronomy and Crop Science》2020,206(3):405-419

  相似文献