Effects of plant architecture and drought stress level on lucerne forage quality

Breeding for enhanced quality in lucerne (Medicago sativa) frequently involves selection for higher leaf‐to‐stem ratio, multifoliolate leaves or short‐internode stems. Three populations selected for such alternative morphologies and a reference cultivar were evaluated for forage yield, leaf‐to‐stem ratio and protein and fibre concentrations in leaves, stems and whole plants. Four managed environments were obtained by combining two stress levels (moderate or nil) with two sowing times. The population selected for high leaf‐to‐stem ratio, as well as the short‐internode population, had highest leaf‐to‐stem ratio (1.27) across six harvests in two non‐stress environments. The latter population had higher stem protein (12.9%) and lower stem neutral‐detergent fibre (NDF) concentration (58.7%) than other populations. The multifoliolate population had intermediate quality, showing low expression of the multifoliolate trait (14.0% across four environments), particularly under stress (10.5%). The autumn‐sown, fully irrigated environment had, on average, highest dry‐matter yield (4.19 t ha^?1) and lowest leaf‐to‐stem ratio (0.74). Drought‐stressed environments had lower plant NDF (?12.3% on average) and leaf protein (?9.7%), and higher stem protein (+8.6%) than fully irrigated environments. The results suggested that environmental effects might have greater impact on quality than genetic effects, even for a population set including material selected for quality‐driven morphology.     

Root development of Thuja plicata in peat-substitute rooting media

In this study we investigated the potential usefulness of different substrates produced from gorse (Ulex europaeus L.) for propagating cuttings of Thuja plicata ‘Atrovirens’. The gorse was composted by different methods, to produce four types of compost. These composts were then used as such (100% compost) or in mixes with coarse sand and pine bark compost (25% compost, 25% coarse sand and 50% pine bark compost, v/v/v) to prepare eight different substrates. The substrates were compared in cutting propagation trials carried out in a greenhouse, with a standard rooting medium consisting of 25% Sphagnum peat moss, 25% coarse sand and 50% pine bark compost (v/v/v). Cuttings were taken from a garden hedge in March 2003, and comprised shoots of the previous year's growth. The bases of the cuttings were treated with a 0.4% solution of IBA rooting hormone, then inserted into cells filled with the corresponding substrate and placed on a propagation bench. Rooting percentage and visual rooting score were determined in July. The quality of roots was evaluated, as total root length and number of root tips, in July, September and November 2003, by use of a Delta-T Scan system. The rooting success of the cuttings ranged from 75% to 90%, except when the substrate comprised the pure composted gorse, obtained after the shorter period in an enclosed composting system with addition of fertilizer and reuse of leachates. Most of the cuttings in this substrate died and only 4% of the cuttings rooted successfully. Physicochemical characteristics of this rooting medium included very high electrical conductivity, low C/N ratio and high water retention. Addition of coarse sand and pine bark compost to the composted gorse significantly increased the rooting success. The root quality variables differed depending on the substrate considered and date of harvest. The results showed that substrates made from gorse compost are of potential use as a peat substitute for propagating cuttings of T. plicata ‘Atrovirens’. The physicochemical properties of the composted gorse should be determined before its use to establish whether it can be used pure as a substrate for rooting or whether it should be mixed with other substances.     

Production of high yielding red raspberry long canes in a Northern climate

Techniques for the production of raspberry long canes with high yield potential were studied on a research station and in two commercial nurseries in South Norway. Potted ‘Glen Ample’ plants were grown in the open and in polyethylene greenhouses during two seasons in order to optimize cultural practices. Dates of propagation and transfer to the production sites were varied. Following cold storage from December to early June, the canes were tipped (cut) at 160 cm height and grown in open plastic tunnels in the fruiting season for the evaluation of growth and yield performance. Remarkable berry yields of 1.5–3.8 kg per plant (cane) were regularly achieved. When grown in the open, later starts than June 1 (June 15 and July 1) successively reduced yields. On the other hand, an earlier start involves risks of growth cessation due to low spring temperature. When grown in greenhouses, high yields were still possible when plants were transferred from propagation conditions as late as July 1, although optimal yields of nearly 4 kg per plant were obtained with transfer on June 15. In a year with unusually high summer temperatures, the yields of canes produced in the open and in greenhouses did not vary significantly, whereas in the second year with normal summer temperatures, canes produced in greenhouses consistently out-yielded those produced in the open by about 1 kg per cane. Regression analyses revealed that high yields were associated with fruiting cane architecture traits such as cane height, number and length of laterals, and a low proportion of dormant buds. The single most important component was lateral length which alone accounted for 82% of the yield variation. Since lateral lengths increased from the shoot tip towards the base, cane heights in excess of 2 m are required for the attainment of top yields as the uppermost nodes with short and low-yielding laterals then can be eliminated by tipping.     

Divergent selection for shell length in two stocks of small abalone Haliotis diversicolor

To determine whether genetic improvement can be attained through a selective breeding programme, divergent selection for shell length was applied to two stocks of Haliotis diversicolor. Stock A was descended from the cross between males from a Japanese wild population and females from a Taiwan aquacultured population and Stock B was from the Taiwan cultured population, which had been successively cultured in mainland China for about 10 generations. The 10% largest and 10% smallest abalones for each of these two stocks were selected as parents for the large‐selected and small‐selected lines respectively. Equal numbers of abalone were randomly chosen from the two stocks to serve as parents for the control lines before the selection. The selected and control lines were reared under the same conditions at early juvenile, later juvenile and grow‐out stages. Stock A showed a significantly higher response to selection and realized heritability than Stock B (P<0.01). The large‐selected line of Stock A and Stock B grew 12.79% and 4.58% faster than their control lines on shell length respectively. The average realized heritability for shell length was 0.441±0.064 for Stock A and 0.113±0.013 for Stock B. Responses to selection were different at different ages in each stock and the body weights of the selected lines were significantly different from the control lines in both stocks at the grow‐out stage. Asymmetric responses to selection in the two directions were also observed in both stocks. Differences in response to selection and realized heritability between the two stocks are presumably due to genetic variability.     

全射流喷头重要结构参数对水力性能的影响

喷头是喷灌系统中的关键部件,其性能好坏直接影响喷灌的效果。该文提出了一种国内原创的全射流喷头,分析了全射流喷头重要结构参数对其工作性能的影响,通过改变样机尺寸的试验验证理论分析的正确性。结果表明,试验结果与理论分析相符合,影响喷头工作状态的主要结构参数包括信号嘴插拔深度、间隙C、导管长度、位差大小和作用区长短等,最后提出了样机的最佳结构参数。     

模拟干旱胁迫下冬小麦胚芽鞘长度变化及与抗旱性的关系研究

以6个抗旱性不同的冬小麦品种(系)为材料,通过不同浓度的PEG-6000渗透溶液模拟干旱胁迫处理,研究了小麦苗期的胚芽鞘长度、苗高、主胚根长等性状,并与其在大田及防雨棚控水条件下的产量构成和抗旱性的关系进行分析.结果表明,在不同浓度的PEG-600 0渗透溶液干旱胁迫处理下,小麦苗期胚芽鞘长度在品种间差异显著;产量的抗旱指数与苗期不同干旱胁迫处理下的胚芽鞘长度的相关性分析表明,小麦的胚芽鞘长度与其抗旱指数呈极显著正相关(相关系数为0.9600),抗旱性强的品种胚芽鞘较长,抗旱性弱的品种胚芽鞘较短.在不同程度的干旱胁迫处理下,各品种的胚芽鞘长度变化趋势大致相同 ,因此利用胚芽鞘长度可以在早期对小麦的抗旱性进行鉴选.     

湛江沿海五种石斑鱼线粒体DNA的RFLP分析

In this paper, genetic diversity of intraspecies, and genetic relationship of interspecies in Epinephelus spp. (E. merra, E. fario, E. awoara, E. akaara and E. septemfasciatus) were assessed by using mitochondrial DNA restriction fragment length polymorphisms (mtDNA RFLPs).The samples were collected from the coastal area of Zhanjiang,Guangdong province. MtDNA was extracted from the fresh liver tissue by applying a difference centrifugation procedures. Using 17 restriction enzymes with 5-or 6-bp recognition sites, the purified mtDNA was cleaved by single enzymes. These enzymes included BamH Ⅰ,Bgl Ⅰ,Bgl Ⅱ,Dra Ⅰ,EcoR Ⅰ,EcoR Ⅴ,Hind Ⅲ,Kpn Ⅰ,Mlu Ⅰ,Pst Ⅰ,Pvu Ⅱ,Sal Ⅰ,Sca Ⅰ,Sma Ⅰ,Sty Ⅰ,Xba Ⅰ and Xho Ⅰ. The phylogenetic analysis was done using the Neighbor joining(NJ) method and Unweighted pairgroup method with arithmetic mean(UPGMA) method. Genetic diversity indices such as haplotype diversity (h), average genetic distance between haplotypes (P) and nucleotide diversity (π) were calculated using Nei and Li's segment method to quantify the genetic diversity within species. There were 8, 5, 8, 5 and 2 haplotypes detected within E. merra, E. fario, E.awoara, E.akaara and E. septemfasciatus, respectively. The haplotype diversity (h) was 0.8943, 0.6186, 0.9242, 0.6927 and 0.1820,respectively. The average genetic distance between haplotypes (P) was 0.62%±0.31%, 0.64%±0.37%, 1.12%±0.55%,0.72%±0.42% and 0.45%, respectively. And the nucleotide diversity (π) was 0.22%, 0.13%, 0.46%, 0.17% and 0.04%, respectively. The wild groupers in the Zhanjiang Coastal Area exhibited a relative higher level of genetic diversity. The net genetic distance between species (P_net) was 0.0694（E. merra - E. fario）,0.1337（E. merra - E. awoara）,0.1090 E. merra -E. akaara）, 0.1286（E. merra - E. septemfasciatus）,0.1590（E. fario -E. awoara）,0.0825（E. fario -E. akaara）,0.1153（E. fario - E. septemfasciatus）,0.1131 E. awoara - E. akaara）,0.0724（E. awoara -E. septemfasciatus） and 0.1336（E. akaara - E. septemfasciatus）. Both NJ and UPGMA methods yielded an identical phylogenetic tree for the five species. The E. merra and E. fario first clustered together, then joined with E. akaara, and finally clustered with E. awoara and E. septemfasciatus.     

全自动生化分析仪与血气分析仪电解质测定结果比较

为积累人工养殖黄鳍金枪鱼 (Thunnus albacores) 幼鱼基础生理指标数据,该研究测定了不同体长黄鳍金枪鱼幼鱼 (20G组: 20~30 cm; 30G组: 30~40 cm; 40G组: 40~50 cm) 血液钾离子 (K⁺)、钙离子 (Ca²⁺)、氯离子 (Cl⁻)、氢离子 (H⁺)、pH、葡萄糖、乳酸、钠离子 (Na⁺) 和总血红蛋白浓度以及红细胞比容和渗透压。结果显示,黄鳍金枪鱼幼鱼K⁺、Ca²⁺、Cl⁻、H⁺、pH、葡萄糖、红细胞比容数据组间差异不显著 (P>0.05)。20G组的乳酸和总血红蛋白均显著高于其他两组 (P<0.05);30G组的标准化Ca²⁺显著高于其他两组 (P<0.05);Na⁺浓度随着体长的增加逐渐下降,相邻两组间差异不显著 (P>0.05)。结果表明,黄鳍金枪鱼幼鱼在3个体长组中血液指标较稳定,在30G和40G两组之间差异较小,20G组与其他两组差异相对较大,随着体长的增加,血液指标趋于更稳定。     

A comparison of morphology,pathogenicity and restriction fragment patterns of mitochondrial DNA among isolates of Phytophthora porri Foister

Thirteen strains ofPhytophthora porri from five different hosts were compared with respect to their morphology, cardinal temperatures for growth, pathogenicity to leek and cabbage and restriction fragment patterns of mitochondrial DNA. Morphology of vegetative growth was rather similar in most isolates. Those characters which differed among isolates showed overlapping variability and could not be used to distinguish groups, with the exception of production of oogonia and sporangia and the antheridium type. Considerable differences were found in restriction patterns of mitochondrial DNA, isolates from the same host mostly showing identical patterns. Isolates from differentAllium species showed relatively similar restriction patterns if compared to the other isolates. Isolates fromBrassica oleracea proved to be a homogeneous group, quite different from the others with respect to restriction patterns, production of sporangia, production of oogonia, antheridium type and pathogenicity. One isolate, CBS 366.59, isolated from and pathogenic toA. porrum, deviated in many characters from the other isolates. It showed the restriction patterns ofPhytophthora nicotianae and also the high cardinal temperatures for growth typical for this species. The sporangia, however, were distinctly non-papillate and the majority of antheridia was of the paragynous type.     

聚果榕与大果榕隐头果内雌花花柱分布方式及与其传粉蜂间的关系

榕属植物与传粉榕小蜂都依靠榕果内的雌花繁育后代,因此它们之间存在着竞争资源的冲突.测量雌雄同株榕树聚果榕与雌雄异株榕树大果榕雌花期的雌花花柱长度,分析其资源分配方式.结果表明:聚果榕雌花花柱长度呈单峰分布,而大果榕呈双峰分布.在雄花期,聚果榕传粉榕小蜂与种子分别倾向占用不同花梗长度的雌花:种子多靠近果壁,传粉榕小蜂的后代多存在于靠近果腔的雌花子房内,形成空间上的分离.大果榕的种子与传粉榕小蜂则分别产生于雌雄株隐头果中,实现了完全的空间隔离.就此而言,雌雄异株榕树大果榕在解决资源分配的竞争冲突中具有更大的优势.