大鸭梨与苹果梨F_1代染色体数目鉴定

用去壁低渗法对大鸭梨与苹果梨Ｆ１代１６个单株的染色体数目进行了鉴定。结果发现,４个单株为四倍体（２ｎ＝４ｘ＝６８）,占观察总数的２５％;１０个单株为三倍体（２ｎ＝３ｘ＝５１）,占观察总数的６２．５％;１个单株为二倍体（２ｎ＝２ｘ＝３４）;１个单株为非整倍体。多倍体出现率为８７．５％,表明大鸭梨与苹果梨杂交组合在多倍体育种中具有特殊价值。     

农田土壤水分和电导率空间变异性及确定其采样数的方法

应用传统统计学和地统计学方法 ,分析了 2个氮肥用量间夏玉米田间 2个 10 m× 10 m区域土壤含水量和电导率的空间变异性 ,在此基础上 ,应用普通克立格技术估算了未知点的土壤含水量和电导率 ,并确定了 2种土壤特性的合理采样数目。结果表明 ,不同的氮肥用量不但影响土壤电导率的分布规律 ,而且影响土壤含水量的分布规律 ;土壤含水量和电导率的半方差函数揭示了它们的分布具有强烈的空间自相关性 ,纯块金效应除外 ;在本试验条件下 ,应用克立格方法 ,土壤含水量和电导率采样效率比传统统计学方法提高 6～ 8倍     

马占相思染色体核型分析

研究马占相思的染色体数目及核型。马占相思体细胞染色体数目为２ｎ＝２６，９对（Ｎｏ．２，４，６，８￣１３）为中部着丝点染色体，４对（Ｎｏ．１，３，５，７）为近中部着丝点染色体，其中第１对（Ｎｏ．１）染色体上具小随体（ｓａｔ），其核型组成为Ｋ（２ｎ）＝２６＝１８ｍ＋８ｓｍ（２ｓａｔ），染色体长度比（最长／最短）为２．５０，臂比均小于２，属Ｓｔｅｂｂｉｎｓ“１Ｂ”核型类型。     

杂交稻黔优301不同施尿素量和栽插株数试验

2006年在贵阳郊区(海拔1140 m)用杂交稻新品种黔优301进行了一组不同施肥量和栽插株数的栽培试验,在蚕豆绿肥田不施用农家肥,只施用尿素,机耕,4月初播种和密度1.2万窝/667m2的条件下,栽插株数间差异不显著,施肥量间差异极显著,最佳栽培处理为栽插1株,施尿素3次,共15 kg/667m2,产量为670.0 kg/667m2。并讨论了该品种的高产栽培技术措施。     

Yak Calving Interval and Calving Efficiency

The results of 439 times of calving interval(CI) from 161 yak cows showed that the average CI is 459(se=131)d. The CI with 3 to 6 calving numbers is 25～48 d shorter than that of 1 to 2 and above 7 calving numbers. Although slaughtering a great number of calves during the late September and early October do bring about relatively higher calving rate that is mos yak cowst can give 3,4,5 and 6calves during 4,5,6 and 7 years old respectively. This makes major calving months shift from April or May to June.     

四倍体沙01梨F_1代染色体数目鉴定

本文对四倍体沙 0 1梨 F1 代单株进行了染色体数目鉴定 ,共 8个组合 1 0 7株 ,发现4 9株三倍体 2 n=3 x=51 ,其中 1株为大水核×沙 0 1 F1 代 ,2 6株为沙 0 1×大南果梨 F1 代 ,3株为大南果梨×沙 0 1 F1 代 ,1 1株为沙 0 1×秦酥 F1 代 ,2株为安梨×沙 0 1 F1 代 ,6株为沙 0 1×金花 4号 F1 代 ,三倍体出现率为 4 5.8 ;1株为四倍体 2 n=4 x=68 ,系安梨×沙 0 1 F1 代 ,占观察总数的 0 .9 ;1 0株为非整倍体 ,均为三倍体作母本的 F1 代 ,占观察总数的 9.3 .结果表明 ,沙 0 1梨作母本 ,二倍体大南果梨作父本 ,是获得三倍体单株的理想组合 ,沙 0 1是倍性育种的优异种质资源     

氯前列烯醇对母蓝狐产仔率及胎产仔数影响的初步研究

为探索进一步提高母狐产仔率及胎产仔数的有效途径和方法,在狐的人工授精程序中通过向精液加入不同剂量的PGF2α类似物———氯前列烯醇,比较各组母狐产仔率、胎平均产仔数,以及各组精子在体外的活力变化。结果表明,氯前列烯醇可以提高母蓝狐的产仔率、胎产仔数,改变精子的休眠状态并活化精子,对狐繁殖具有积极作用,在生产中具有一定的应用价值。     

驴胎皮肤继代细胞核型的初步分析与鉴定

对18代驴胎皮肤继代细胞染色体作了初步分析与鉴定。精确计数分析结果为二倍体61％,多倍体3.7％,亚二倍体15％,超二倍体6％,断裂1％;核型分析为62/XY型。     

Maize kernel growth and kernel water relations as affected by nitrogen supply

Improving maize (Zea mays L.) growing conditions near flowering by applying nitrogen (N) could affect both kernel number per unit area (KN) and potential kernel weight (KW). Potential kernel weight can be estimated with maximum kernel water content (MKWC), as final kernel weight and kernel water relations are strongly associated in maize. At the crop level, the product of KN per unit area and MKWC could provide an appropriate index of potential sink capacity. The main objective of this study was to determine if the decrease in potential sink capacity (i.e. the product of MKWC and KN), under N deficit and with a late planting date, is due to MKWC or KN reductions. Additionally, we evaluated sink growth rate per unit area (i.e. the product of KN and kernel growth rate) during grain fill period as related to potential sink capacity. Three N rates under optimal and late planting dates and two hybrids were evaluated in experiments carried out at Paraná, Argentina (31°50′S; 60°31′W) during 2002–2003 and 2003–2004 growing seasons (seasons 1 and 2, respectively). Except for the late planting date during season 1, there was a significant positive response on grain yield, KN, KW, and MKWC to N supply. Experiments explored a broad range of KN, from 1645 to 5066 kernel m⁻². MKWC and KN were positively correlated for DK682. Nitrogen increased the potential sink capacity and sink growth rate only as KN increases from a particular threshold in both hybrids. The sink growth rate was largely related to potential sink capacity, as MKWC was highly correlated with KGR across all treatments. Our analytical approach, considering potential sink capacity as a product of KN and MKWC, is integrative of sink demand both for individual kernel and crop levels. This work highlights the role of early establishment of potential sink capacity on yield determination under a wide range of N conditions.     

New C-banding pattern for chromosome identification in cucumber (Cucumis sativus L.)

A chromosome study of cucumber, C. sativus L., was performed using orcein and C-banding techniques. The diploid and tetraploid plants investigated here showed the somatic chromosome numbers 2n=14 and 28, respectively. The haploid chromosome complement was composed of five metacentric and two submetacentric chromosomes. All C. sativus chromosomes had clearly visible C-bands, and each chromosome could be identified unequivocally after C-banding staining, with 13 C-bands appearing in the haploid complement. The haploid complement had a 44.9% ratio of total C-band length to total chromosome length. Chromosomes 1, 2, 4, 5 and 7 had stable C-bands. Three large, dark C-bands appeared at the proximal regions of chromosomes 1 and 2. Chromosome I had quite a large C-band and with a 68.4% ratio of C-band length to short arm length. Chromosome 2 also had quite a large C-band in the pericentromeric region with a 57.6% ratio of C-band length to the full length of this chromosome and possessed an elongated primary constriction in early metaphase. In prometaphase, chromosome 2 showed that the long arm was completely separated from the short arm. The number of secondary constrictions could not be clearly observed because these chromosomes are small and they could not be counted in every metaphase cell. However, six chromosomes seemed to have secondary constrictions in the diploid plants. Two silver-stained bands were observed at primary constrictions of two of the large chromosomes.