Optimal set of microsatellite markers required to detect illegitimate progenies in selected oil palm (Elaeis guineensis Jacq.) breeding crosses

Oil palm is continually being improved via controlled crossing of selected palms to ensure sustainable yields and productivity. As such, correct parental assignment is important as the presence of illegitimates will compromise the progress of improvement. In the present study, we determined the optimal number of microsatellite (SSR) markers for detection of illegitimates in selected oil palm crosses with high confidence. Determining the optimal number of markers to assign parentage will ensure that the DNA fingerprinting will be cost effective for routine use as a quality control tool in oil palm improvement programs. Here, we evaluated a wide range of crosses that included a cross derived from wild germplasm palm. The results revealed that markers with high PIC are informative and detect most of the alleles present in a cross, including those exhibited by the illegitimates. A larger number of optimum sets of markers are needed to detect all illegitimates for crosses with higher levels of genetic diversity. The optimal number of polymorphic SSR markers determined in the present study can ensure that appropriate quality control is implemented for oil palm improvement programs.     

种植关键技术对‘灿烂’蓝莓叶片黄化症的矫治效果分析

针对玉溪蓝莓生产上易发生生理性缺铁黄化症的问题,以‘灿烂’为参试对象,2017—2018年采用田间试验与室内分析的方法开展研究。结果表明,采用以酸性微生物有机肥+蓝莓土壤改良基质调节土壤酸度,平衡N、P、K肥与全水溶性有机肥配合施用,土壤和叶面施用螯合铁等为主的蓝莓种植关键技术,能显著降低蓝莓根际土壤pH而提高有效Fe含量,使轻度黄化株及中度黄化株矫治为正常株或基本正常株,重度黄化株矫治为轻-中度黄化株;叶片的SPAD值及Fe、Mn含量显著提高,Ca/Fe、Ca/Mn比值降低,蓝莓果粒饱满,百粒重增加,为蓝莓生产上矫治生理性缺铁黄化症提供了参考依据。     

星云湖径流区施肥对洋葱产量及不同土层养分残余量的影响

针对星云湖径流区蔬菜面积扩大、过量施肥,导致土壤养分残余量加大,对湖水质量产生影响的实际问题,采用田间试验研究不同施肥技术对洋葱产量的影响,探讨了试验前后不同土层养分变化情况。结果表明：不同施肥技术对洋葱产量影响不明显,以每公顷施N 450 kg、P₂O₅ 0 kg、K₂O 150 kg,并采用10%氮肥及50%钾肥作基肥施于移栽沟中、20%氮肥移栽后15天兑水追施、70%氮肥及50%钾肥鳞茎膨大初期兑水追施的施肥技术产量最高。0~35 cm层及35~50 cm层的土壤速效N残余量随着施N量的增加而显著提高,而50~75 cm层的土壤速效N残余量则略有降低;0~35 cm层的土壤有效P及速效K的残余量相应地随着P₂O₅、K₂O施用量的增加而显著提高,但耕作层以下的各层土壤有效P及速效K的残余量只是略有提高。     

Responses in growth rate of larval northern anchovy (Engraulis mordax) to anomalous upwelling in the northern California Current

We examined variability in growth rate during the larval stage of northern anchovy (Engraulis mordax) in response to physical and biological environmental factors in 2005 and 2006. The onset of spring upwelling was anomalously delayed by 2–3 months until mid‐July in 2005; in contrast, spring upwelling in 2006 began as a normal year in the northern California Current. Larval and early juvenile E. mordax were collected in August, September, and October off the coast of Oregon and Washington. Hatch dates ranged from May to September, with peaks in June and August in 2005 and a peak in July in 2006, based on the number of otolith daily increments. Back‐calculated body length‐at‐age in the June 2005 hatch cohort was significantly smaller than in the August 2005 cohort, which had comparable growth to the July 2006 cohort. Standardized otolith daily increment widths as a proxy for seasonal variability in somatic growth rates in 2005 were negative until late July and then changed to positive with intensification of upwelling. The standardized increment width was a positive function of biomass of chlorophyll a concentration, and neritic cold‐water and oceanic subarctic copepod species sampled biweekly off Newport, Oregon. Our results suggest that delayed upwelling in 2005 resulted in low food availability and, consequently, reduced E. mordax larval growth rate in early summer, but once upwelling began in July, high food availability enhanced larval growth rate to that typical of a normal upwelling year (e.g., 2006) in the northern California Current.     

能源植物石栗ISSR-PCR体系的建立与优化

对能源植物石栗种质资源的遗传多样性进行研究,建立了其ISSR-PCR分子标记体系.应用CTAB法提取石栗叶片基因组DNA,用正交设计和单因素水平优化的方法对ISSR-PCR反应程序中的一些重要参数进行筛选和优化.结果表明,25 μLISSR-PCR反应体系的最优条件为:DNA模板20 ng、Mg2+ 1.5 mmol/L,Taq DNA聚合酶1.5 U,引物0.40μmol/L,dNTP 200 μmol/L.     

Estimating the outcrossing rate of Cyperus difformis using resistance to ALS-inhibiting herbicides and molecular markers

Cyperus difformis (smallflower umbrella sedge) is an economically important weed of rice in California where its control has recently been complicated by the evolution of herbicide resistance. Knowledge of the mating system of this weed is needed to elucidate the dynamics of resistance evolution and to design mitigation strategies that delay its occurrence. The aim of this study was to estimate the outcrossing rate of C. difformis using molecular and phenotypic markers. Outcrossing rates were estimated in natural field populations using sequence-related amplified polymorphism (SRAP) molecular markers and in glasshouse and field experiments using resistance to the acetolactate synthase-inhibiting herbicide bensulfuron-methyl as a phenotypic marker. Using SRAP markers, the multilocus ( t _m) and average single-locus ( t _s) outcrossing rates varied from 0.014 to 0.025 and from 0.008 to 0.012, respectively, among natural weed populations in rice fields. Using resistance to bensulfuron-methyl as a genetic marker, the average C. difformis outcrossing rate estimated was 0.009 in the glasshouse and 0.0084 in the field. These results indicate that C. difformis is a highly self-fertilising species. Therefore, the primary mechanism by which genes for herbicide resistance can be transferred among C. difformis populations in different rice fields is probably seed dispersal. Weed management should emphasise prevention of seed production and dispersal to preclude the further spread and evolution of resistance in C. difformis .     

绿茶保鲜技术研究进展

对目前应用于绿茶贮藏保鲜技术研究的新进展进行了综述,并对未来绿茶保鲜技术的发展进行展望,提出发展方向,以期为茶叶加工和贮藏保鲜提供理论依据。     

HPLC-ELSD法优化益母草中盐酸水苏碱提取工艺研究

试验旨在运用HPLC-ELSD法对益母草中盐酸水苏碱进行分离分析,建立益母草盐酸水苏碱含量测定的方法,为益母草提取工艺的优化提供理论依据。色谱条件:色谱柱为Venusil HILIC亲水型色谱柱;流动相为乙腈-0.2%冰醋酸溶液(体积比80:20);流速为1.0 mL/min;柱温为30 ℃;检测器:ELSD;漂移管温度 80 ℃,雾化室温度50 ℃,载气体积流量1.0000 mL/min。结果显示,盐酸水苏碱在0.49~4.91 μg时线性关系良好(R²=0.9993);在提取时间为1 h,提取次数为2次,料水比为20:1条件下,益母草有效成分提取率最高。结合生产实际,最终优化的提取方案:提取时间1.5 h,提取数2次,料水比为20:1。综上所述,对于益母草中盐酸水苏碱含量的测定,宜采用高效液相色谱的方法,同时应用蒸发光散射检测器。此方法具有特异性强、稳定性好、反应灵敏、操作简便、重现性好等特点,可为益母草提取工艺的优化提供相应的理论依据。     

Assessing the Relative Importance of Nitrogen-Retention Processes in a Large Reservoir Using Time-Series Modeling

Nitrogen (N) removal within reservoirs can be substantial, but few studies have reported the relative importance of various N-retention pathways. Assessing N-removal processes in reservoirs is important for quantifying the impacts of reservoirs on downstream water quality. In this study, we used a time-series approach to quantify the relative importance of various N-removal processes in the Saylorville Reservoir in Iowa. Dynamic regression modeling of upstream–downstream changes in key water-quality surrogates (pH, hardness, alkalinity, and suspended solids) and their relation to N concentration changes were used to estimate the relative importances of denitrification, N assimilation by algal uptake, and sedimentation of N on N retention in the reservoir. Assuming that decreasing N concentrations in the reservoir are the sum of these three processes, we estimate that denitrification is the dominant N removal process (60.9 %) followed by algal assimilation (37.9 %) and sedimentation (1.2 %). Our approach represents a new method of establishing the relative importance of N-removal processes in reservoirs and quantifying the impacts of reservoirs on downstream water quality.     

Pacific hake (Merluccius productus Ayres, 1855) hydrolysates as feed attractants for juvenile Chinook salmon (Oncorhynchus tshawytscha Walbaum, 1792)

Soybean meal (SBM) inclusion in salmonid diets can lower feed cost, but dramatically reduces growth and feed utilization, and increases mortality in juvenile chinook salmon Oncorhynchus tshawytscha, due to diminished diet palatability and/or other adverse physiological effects exerted by antinutritional factors in SBM. The objective of this study was to investigate whether commercial Antarctic krill meal Euphausia superba or hydrolysates enzymatically produced from Pacific hake Merluccius productus could reverse the negative palatability effects of SBM inclusion in juvenile chinook salmon diets. Diets without SBM or with SBM and no added feed attractant were used as positive and negative control diets respectively. Incorporation of 2% krill meal or Alcalase^®‐produced hydrolysates into SBM‐containing diets (20% of dry matter by isonitrogenous replacement of fishmeal) significantly (P < 0.05) increased feed intake, feed utilization, fish weight gain and thermal growth coefficient during a 5‐week trial. Nevertheless, the negative effects on fish performance incurred by dietary inclusion of 20% SBM could not be fully reversed, indicating that most of those effects were likely unrelated to palatability. This study demonstrates the potential for using Pacific hake hydrolysates as a dietary feed attractant for salmonid diets, and supports the need for further research to optimize its application for ideal fish performance.