Inheritance of long juvenile period under short day conditions for the BR80-6778 soybean (Glycine max (L.) Merrill) line

The long juvenile period characteristic (LJP), which delays flowering under short day conditions, has been identified in soybean cultivars (Glycine max L. Merrill). This characteristic may be especially important as it increases the range of adaptation of soybean in low latitudes and gives greater flexibility for sowing periods within the same latitude. The inheritance of the long juvenile period was studied in the BR80-6778 soybean line to provide knowledge to support the development of cultivars adapted to short day conditions. Cultivars with classic flowering, Paraná, Bossier, Bragg and Davis, which flower early under short day conditions, were also used as parents in single crosses. They were crossed among themselves and with the genotypes with LJP, BR80-6778 and MG/BR 22 (Garimpo). The study was carried out under short day conditions (early sowings) in greenhouses and in the field at Embrapa National Soybean Research Center, Londrina, PR. Flowering was assessed daily. The results indicated that the BR89-6778 line shares a pair of alleles with the Paraná cultivar, and when associated with the cc allele retards flowering under short day conditions. The following genotype constitutions were attributed to the cultivars: Paraná (aaBBCC), Bossier (AabbCC), and BR80-6778 (aaBBcc). The combination of the genes aabb and aabbcc has a pronounced effect on the manifestation of the trait. This revised version was published online in July 2006 with corrections to the Cover Date.     

长白高等级公路石灰、粉煤灰做路面底基层的强度规律

采用室内实验并结合道路施工中实际情况研究了石灰、粉煤灰做路面底基层的强度规律。主要研究３方面因素对石灰,粉煤灰做路面底基层强度的影响。包括单质材料、石灰与粉煤灰的比例及龄期。     

协方差分析方法优化农用车悬架参数

介绍了协方差分析随机振动的基本原理,建立了５自由度的农用车平面模型和状态方程,给出了评价农用车行驶平顺性的目标函数,通过协方差方法得出目标函数随悬架的阻尼和刚度变化的关系,用实例验证利用这种方法优化农用车悬架参数是可行的。     

几种土壤剖面的硝化作用及其动力学特征

选用陕西省六种主要耕作土壤及其剖面不同层次23个土样,在实验室培养条件下,研究其硝化作用的特点,并选用dN/dt=bN(B-N)/B方程（式中,N为硝态氮的累积量,t为试验培养时间,B耿硝态氮累积量的渐进值）,描述硝化作用过程中硝态氮含量随时间的累积,获得定量描述硝化作用强弱的两个指标（Kmx和td)。结果表明耕层土壤由北向南硝化作用强度逐渐减弱,硝化作用的最大速率（Kmx)变幅为2．70－16．58mg/kg.d,陕北的黑垆硝化作用进行最快,陕南的黄泥巴最慢,在不同土壤剖面中,硝化作用由上到下呈现减弱趋势,硝化作用的最大速率（Kmx)随土层深度增加而下降,迟缓期（td)随土层深度增加而延长,在粘化层和粘重土层中,硝化作用非常微弱或基本不发生硝化作用,这些不同土壤及剖面层次硝化作用的较差与土壤的物理,化学特性有关。     

银中杨扦插育苗试验

通过不同型号、不同浓度ABT生根粉处理的银中杨扦插苗试验表明 :ABT生根粉促进银中杨扦插苗生根作用明显 ,生根时间可提前一周 ,以一号、六号含原液质量分数为 1.0× 10 - 4的浓度 ,效果最佳 ,成活率达 80 %。高生长较对照提高 1.5倍。纯增效益 4 .5万元 /hm2 。     

Optimal feed level during the transition period to achieve faster farrowing and high colostrum yield in sows

This study aimed to determine the optimal supply of lactation feed during the transition period to minimize farrowing duration (FD) and maximize colostrum yield (CY) and quality with the overall aim of reducing piglet mortality. A total of 48 sows were stratified for body weight and assigned to six levels of feed supply (1.8, 2.4, 3.1, 3.7, 4.3, and 5.0 kg/d) from day 108 of gestation until 24 h after the onset of farrowing. The number of total born, live-born, and stillborn piglets; birth time and birth weight of each piglet; and frequency of farrowing assistance (FA) was recorded, and blood samples were obtained from newborn piglets at birth. Live-born piglets were further weighed at 12 and 24 h after birth to record weight gain, which in turn was used to estimate intake and yield of colostrum. Colostrum samples were collected at 0, 12, 24, and 36 h after the onset of farrowing. FD was shortest (4.2 h) at intermediate (3.7 kg/d), longest (7.1 to 7.6 h) at low (1.8 and 2.4 kg/d), and intermediate (5.6 to 5.7 h) at high (4.3 and 5.0 kg/d) feed intake (P = 0.004; mean comparison). FA was lowest (0.7% to 0.8%) at intermediate feed intake (3.7 and 4.3 kg/d) and substantially elevated (4.3% to 4.7%) at both lower and higher feed intake (P = 0.01; mean comparison). The cubic contrast revealed 4.1 kg/d as the optimal feed intake to achieve the shortest FD and to minimize FA. Newborn piglets from second-parity sows were less vital than piglets from gilts as evaluated by blood biochemical variables immediately after birth. CY was greatest at 3.1 kg/d (P = 0.04), whereas the cubic contrast revealed 3.0 kg/d as the optimal feed intake to maximize CY. Concentrations of colostral components were affected by the diet, parity, and their interaction except for lactose concentrations. In conclusion, the study demonstrated the importance of proper feed level during the transition period on sow productivity. Moreover, this study estimated 4.1 and 3.0 kg/d as the optimal feed intake during the transition period to improve farrowing characteristic and CY, respectively, and these two feed intake levels supplied daily 38.8 MJ metabolizable energy (ME) and 23.9 g standardized ileal digestible (SID) lysine (3.0 kg/d) or 53.0 MJ ME and 32.7 g SID lysine (4.1 kg/d). The discrepancy of optimal feed intake for optimal farrowing and colostrum performance suggests that it may be advantageous to lower dietary lysine concentration in the diet fed prepartum.     

国外优良材用竹种阿帕斯竹引种栽培试验

阿帕斯竹出笋期5月中旬～10月中旬,7月上旬～8月中旬为出笋盛期;单株埋秆育苗的出笋数、成竹数分别是单株埋蔸育苗的3.9倍、3.8倍,而新竹径级较埋蔸的下降43.5%,两种育苗方法可结合应用;竹丛结构调控可显著提高竹丛出笋数(21.9%)和新竹地径(84.1%),退笋率降低36.9%;综合出笋成竹数、新竹地径的季节性施肥效果,以6月最佳,其次为3月。     

茶杆竹笋期生长规律及立竹密度研究

对茶杆竹出笋成竹规律及其合理立竹密度进行研究,表明茶杆竹出笋量随时间的变化进程为“少-多-少”。茶杆竹笋期呈“S”型曲线。不同笋期的茶杆竹高生长方程相关系数为0．9371-0．9418．经检验,达到显著水平,表明用Logistic方程回归效果较好。茶杆竹立竹密度试验表明茶杆竹林分密度应以11250株／hm^2为适宜。     

柑橘矢尖蚧发生期预测回归方程研究

矢尖蚧是危害柑橘生产的重要害虫之一,搞好测报可以指导适时防治.笔者在重庆市北碚区柑橘园对矢尖蚧进行多年系统监测,结果表明,矢尖蚧在该地一年发生3代,世代重叠,第1代发生较为整齐,便于统一防治.因此,以2012年-2018年该虫发生前3个月的气象资料和矢尖蚧发生的田间历史数据为依据,应用DPS软件,分别采用简单法和多因子...     

配合饲料饲喂育成期水貂消化试验及饲养效果观测

将68只水貂按雌雄、体质量随机分为两组,分别饲喂常规鲜料(对照组)和配合饲料(试验组),在育成期进行饲养试验和消化试验。结果表明:母貂干物质和粗蛋白表观消化率对照组均高于试验组(P<0.05),公貂干物质和粗蛋白表观消化率对照组均显著高于试验组(P<0.01);试验组水貂干物质采食量和可消化干物质均略高于对照组;粗脂肪和粗纤维表观消化率试验组均高于对照组,差异极显著(P<0.01);对照组和试验组水貂能量表观消化率差异不显著(P>0.05);试验组水貂质量的增加均大于对照组。试验结果证实,采用配合饲料与一定比例的新鲜原料喂养水貂,是提高水貂生长性能、解决其饲料来源困难的比较合理的办法。