Molecular characterization and genetic relationship among almond cultivars assessed by RAPD and SSR markers

RAPDs and SSRs were used to study the genetic diversity of Iranian almond cultivars and their relationship to important foreign cultivars and three related species. Eight unidentified almond Shahrodi cultivars and three wild almonds (Prunus communis, Prunus orientalis and Prunus scoparia) were also included. Of the primers tested, 42 (out of 80) RAPD and 18 (out of 26) SSR primers were selected for their reproducibility and high polymorphism. A total of 664 polymorphic RAPD bands were detected out of 729 bands. The number of presumed alleles revealed by the SSR analysis ranged from 3 to 10 alleles per locus with a mean value of 6.64 alleles per locus. Both techniques discriminated the genotypes very effectively, but only RAPDs were able to discriminate the cultivars Monagha and Sefied. Results demonstrated an extensive genetic variability within the tested cultivars as well as the value of SSR markers developed in peach for characterization of almond and related species of Prunus. Dice similarity coefficient was calculated for all pair wise comparisons and was used to construct a UPGMA dendrogram. For both markers a high similarity in dendrogram topologies was obtained although some differences were observed. All dendrograms, including that obtained by the combined use of both the marker data, depicted the phenetic relationships among the cultivars and species, depending upon their geographic region and/or pedigree information. Almond cultivars clustered with accession of P. communis showing their close relationship. P. orientalis and P. scoparia were clustered out of the rest of P. dulcis.     

垄沟秸秆覆盖还田对耕层土壤结构性及含水量的影响

垄沟秸秆覆盖是防治坡耕地水土流失的耕作措施之一,具有显著的蓄水拦沙作用.在垄沟秸秆覆盖轮耕还田后,耕层土壤的团聚体含量显著增加,粒径集中于1～7 mm组分内;同时,土壤容重有效降低,自然含水量平均提高了 21％,相对含水量显著提高,田间持水量与全蓄水量均有所增加.表明土壤的保水能力显著提升,可快速吸纳降水,从而减小地表径流量,提高土壤的抗水蚀能力.     

Nonparametric phenotypic stability analysis in advanced barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) genotypes

The development of genotypes with adaptation to a wide range of environments is one of the most important goals of plant breeding programs. In order to compare nonparametric stability measures and to identify promising high-yield and stable barley (Hordeum vulgare L.), 20 barley genotypes selected from the Iran/ICARDA joint project and grown in nine environments during 2009-11 in Iran. Four nonparametric statistical tests of significance for genotype × environment (GE) interaction and 10 nonparametric measures of stability were used to identify stable genotypes in nine environments. Results of nonparametric tests of G×E interaction (Kubinger, Hildebrand, and Kroon/ Laan) and a combined ANOVA across environments, indicated the presence of both crossover and non-crossover interactions. Also, only TOP and rank-sum values were positively associated with high yield. Thus, in the simultaneous selection for high yield and stability, only the rank-sum and TOP methods were useful in terms of the principal component analysis results, and correlation analysis of nonparametric stability statistics and yield. According to these stability parameters (TOP and rank-sum), three genotypes (G13, G12, and G17) were the most stable for grain yield. The results also revealed that based on nonparametric test results, stability could be classified into three groups, according to agronomic and biological concepts of stability.     

Amplified fragment length polymorphism as a tool for molecular characterization of almond germplasm: genetic diversity among cultivated genotypes and related wild species of almond,and its relationships with agronomic traits

Amplified fragment length polymorphism (AFLP) analysis is a rapid and efficient method for producing DNA fingerprints and molecular characterization. Our objectives were to: estimate genetic similarities (GS), marker indices, and polymorphic information contents (PICs) for AFLP markers in almond cultivars; assess the genetic diversity of almond cultivars and wild species, using GS estimated from AFLP fingerprints and molecular characterization; and facilitate the use of markers in inter-specific introgression and cultivar improvement. The genetic diversity of 45 almond cultivars from Iran, Europe, and America, were studied assaying 19 primer combinations. In addition, several agronomic traits were evaluated, including flowering and maturity times, self-incompatibility, and kernel and fruit properties. Out of the 813 polymerase chain reaction fragments that were scored, 781 (96.23%) were polymorphic. GS ranged from 0.5 to 0.96, marker indices ranged from 51.37 to 78.79, and PICs ranged from 0.56 to 0.86. Results allowed the unique molecular identification of all assayed genotypes. However, the correlation between genetic similarity clustering as based on AFLP and clustering for agronomic traits was low. Cluster analysis based on AFLP data clearly differentiated the genotypes and wild species according to their origin and pedigree, whereas, cluster analysis based on agronomic data differentiated according the pomological characterization. Our results showed the great genetic diversity of the almond cultivars and their interest for almond breeding.     

电刺激对产后母猪行为及生产性能的影响

解救被压哺乳仔猪是提高规模化养殖场生产效益的重要手段,其中电刺激是最新技术之一,为优化目前电刺激技术研究参数单一,母猪过度反应等问题,该研究基于反应有效性和惊吓指数两类参数分析了产后母猪不同身体部位在不同刺激电压下的反应,确定了电刺激技术参数适宜值,并验证了该参数对母猪生产性能的影响。结果表明：电刺激装置通电0.5 s后,母猪在刺激电压2 000和2 400 V下的有效反应率皆为75%以上,且这2种刺激电压下发生有效反应的概率极显著高于1 200 V(P<0.01)。母猪腰部的有效反应率为70.8%,该部位发生有效反应的概率比侧腹部和大腿根部高将近3倍左右。当刺激部位为腰部,刺激电压为2 400 V时,母猪惊吓指数上限高于60%;当刺激部位为腰部,刺激电压2 000 V时,惊吓指数上限低于60%,综合有效反应和惊吓指数结果,建议电刺激适宜参数为：电压2 000 V,刺激部位为腰部。生产试验结果表明：在整个哺乳期,执行电刺激适宜参数的试验组母猪的平均日采食量（5.50 kg）和断奶窝质量（58.91 kg）略高于对照组的日采食量（5.45 kg）和断奶窝质量（58.42 kg）,但...     

荒漠绿洲交错区生态空间网络粒度效应研究

以乌兰布和沙漠东北缘磴口县为研究区,针对县域生态空间网络的粒度效应开展研究。结果表明,空间粒度的变化对生态空间网络的空间结构、拓扑结构以及生态源地的面积与空间分布均具有明显的影响,而生态阻力的粒度效应并不明显。随着空间粒度的不断增大,生态源地的面积产生了明显的波动并且变得越发破碎;生态空间网络长度经历了从增加到减少的变化,其空间分布由最初的不断密集再到逐渐稀疏;生态空间网络的各项拓扑结构指数变化较为明显,随着空间粒度的不断升高,网络的度分布愈发集中,同配性、层次性、模块化增强,网络的不均匀性不断提升,连接性不断降低,总体向更加不稳定的方向变化。     

Phenotypic diversity within native Iranian almond (<Emphasis Type="Italic">Prunus</Emphasis> spp.) species and their breeding potential

A total of 137 accessions from 18 wild almond species were collected from Iran and leaf and fruit traits were characterized. Also evaluated were flowering and ripening date, self-incompatibility and kernel bitterness. An extensive phenotypic diversity was found both among and within species. Differences in average leaf dimensions among and within species were associated with average rainfall but not altitude of collection site. Adjacent accessions located in drier areas had smaller leaf dimensions than those located in semi-humid or humid regions. No relation was found between average fruit dimensions and collection site conditions. Principal component analysis revealed that the nut weight and width, and the kernel weight had highest loading in the first component accounting for 45.8% of total variation. In contrast, leaf traits in the second component accounted for 22.3% of total variation. No significant correlations were detected between leaf dimensions and fruit traits in all species evaluated. Results document a rich source of new germplasm for almond improvement programs. Small fruit size, pollen-pistil self-incompatibility, and bitter kernel flavour are the most common obstacles to the utilization of this wild germplasm in breeding.     

The use of parametric and non-parametric measures for selecting stable and adapted barley lines

This research was carried out to estimate yield stability of 18 barley breeding lines using different parametric and non-parametric statistics across 15 environments during 2012–2015 growing seasons. The results of combined analysis of variance (ANOVA) and additive main effect and multiplicative interaction (AMMI) analysis showed that environments (E), genotypes (G), GE interaction, as well as the first four interaction principal component axes were highly significant, suggesting that the lines interacted differentially with environments, so further general adaptability and stability analysis across environments should be followed before being introduced for cultivation. Based on correlation coefficient and principal components analysis (PCA), most of the non-parametric statistics were significantly inter-correlated with parametric statistics, hence seem to be suitable alternatives to complement parametric statistics. Furthermore, according to the static and dynamic concepts of stability, the results revealed that stability statistics can be clustered into three groups. The overall stability analysis following different stability methods concluded that four lines (G5, G7, G17 and G20) were highly stable for grain yield in rain-fed conditions of subtropical regions of Iran. Thus, these lines can be recognized as the most stable lines for cultivation in diverse environments of semi-warm regions of Iran.     

EFFECT OF TIMBER DENSITY ON RETENTION OF WOOD PRESERVATIVES

The amount of CCA fixed in the southern pine treated with CCA have been eval-uated.The conclusions from these experiments are:with the timber density increases,the reten-tion based on weight/weight will decrease,but the retention based on weight/volume will bealmost constant.Retention by weight would be more influential than by volume.     

The effect of in planta TIBA and proline treatment on somatic embryogenesis of sugar beet (Beta vulgaris L.)

The effect of in planta TIBA and L-proline onin vitro seedlings and cell culture of sugar beet was investigated. Sterilized seeds were grownin vitro on 1/2 MS medium supplemented with 0 or3 mg/l TIBA. Calli obtained on young leaves cultured on MS medium containing 1 mg/l BAP, were used for the initiation of cell suspension cultures using MS basal composition supplemented with 0 or 50 mM proline. Aliquots of 1 ml from cell suspension culture were inoculated onto the first somatic embryo induction MS medium containing TIBA 0.5 mg/l, BAP 1.0 mg/l, and proline at 0 or 50 mM. After three weeks of culture, embryogenic calli were transferred to the second embryo induction medium supplemented with NAA and BAP at 0.2 and 0.5 mg/l, respectively. The frequency of somatic embryos of calli obtained from in plantaTIBA together with proline treatments on average was20 which was higher than that of the other treatments. This revised version was published online in July 2006 with corrections to the Cover Date.