Structure and diversity among rhizobial strains, populations and communities-a review

Published studies of rhizobial populations, communities and other strain collections were analysed to identify trends in strain richness, strain dominance and genetic diversity within and between locations. For individual populations and communities, strain richness indices were calculated by dividing the number of strain types identified by the number of isolates recovered. Where possible, strain dominance (the proportion of rhizobial isolates represented by each strain type) was also calculated. Analysis of the genetic diversity of populations, communities and rhizobial strain collections originating from diverse legume hosts and locations, was confined to studies using multilocus enzyme electrophoresis (MLEE) so that diversity could be compared on the basis of published H values. Strain richness indices were highly variable (0.02-0.94) and were influenced by both the discriminatory power of the strain typing method and the type and number of legume species used to recover rhizobia from soil. The strain richness of populations recovered either directly from soil, or from the nodules of trap hosts inoculated with the same soil, was similar. Because the arithmetic relationship between the number of strain types and number of isolates varies between different populations and communities, strain richness curves are proposed as the most appropriate method for reporting rhizobial structural diversity. Comparison of over 50 rhizobial populations and communities from published studies showed that strain dominance patterns in nodules were often similar. Typically, a single strain type occupies more than 30% of nodules with the majority of strain types being recovered at low frequency (∼75% of published populations and communities). Rhizobial populations and communities characterised by MLEE varied in their genetic diversity, with H values ranging from 0.06 to 0.78. In several studies, most of the genetic diversity within a site could be recovered from the nodules of a single plant. When hierarchical analyses were performed on populations within and between sites, the genetic diversity within sites was similar to the genetic diversity between sites. Similarly, the genetic diversity of strain collections originating from multiple hosts and locations was no more diverse than some individual populations and communities. Strain richness and genetic diversity measures were not always correlated for rhizobial populations. Populations with low strain richness were sometimes genetically diverse, and the relationship between the diversity measures varied for different legume species at the same location. We suggest that both strain richness and genetic diversity measures are required to fully describe rhizobial population and community diversity.     

采收期对龙眼果实品质和耐贮性的影响

以福建省主栽龙眼品种油潭本果实为材料，研究采收期(从8月19日到9月12日每隔4 d采果一次)对龙眼果实品质和耐贮性的影响。结果表明：随着采收期的延迟和果实成熟度的提高(8月19日到9月8日采收)，龙眼果皮颜色由青褐色逐渐变成黄褐色，果实由近长圆球形逐渐变成扁圆球形，果实质量和大小逐渐增加，果皮逐渐变薄而果肉逐渐增厚，果肉可食率、营养品质和食用品质提高。但过熟的龙眼(9月12日采收)果皮变成灰褐色，果实品质下降。可用果皮颜色，果实质量和大小，果皮和果肉厚度，果肉可食率、可溶性固形物、总糖、维生素C含量和固     

DRIS norms and limiting nutrients in banana cultivation in the South of Ecuador

Abstract

Foliar analysis is an effective method to diagnose the nutritional status of plants. However, the mineral concentration in foliar tissue has traditionally been evaluated by assessing the activity of each element, without considering the interactions between them. To address this, dual interactions were calculated using the Diagnosis and Recommendation Integrated System (DRIS) to identify which crop nutrients are most influential in nutrient imbalances and which are the most limiting nutrients for the nutritional status of banana crops in Ecuador. To achieve this, a regional survey of the nutritional status and its productivity levels was conducted for 188 different sites during the crop season in 2017–2018, involving banana cultivars ‘Vallery’ and ‘Williams’, from the Cavendish subgroup. The DRIS calculation method was combined with Beaufils and Jones functions. From the initial 188 foliar samples, 83 samples (representing 44% of the population) were considered to represent the high-yield reference population, with yields of 38–60 t ha^?1. The DRIS method defined the mean nutritional balance index, which was not found to be statistically correlated (p?>?0.05) with productivity, revealing that there was no significant association with the nutritional status of the plants. Specific DRIS norms were obtained and indicated that deficiencies in K, N, Ca, and Fe, and excesses in Mn, B, Cl, Zn, S, Cu, and Mg were the most limiting nutrients for banana cultivars in the south of Ecuador.     

NaCl和Na2CO3胁迫对盐爪爪种子萌发过程中生理生化变化的研究

以盐生植物盐爪爪种子为材料,比较不同浓度中性盐(NaCl)和碱性盐(Na2 CO3)胁迫对其种子萌发过程中生理指标的影响.结果表明,0～100 mmol/L NaC1处理后盐爪爪萌发种子中丙二醛含量无显著变化,而0～100 mmol/L Na2CO3处理后丙二醛含量显著升高;NaCl处理的萌发种子中可溶性糖变化较平稳且呈现上升趋势,Na2CO3处理的种子可溶性糖先升高后降低;0～ 100 mmol/L NaCl处理后盐爪爪萌发种子中脯氨酸含量基本保持不变,而0～100 mmol/L Na2CO3处理后脯氨酸含量急剧上升;NaCl处理后可溶性蛋白上升幅度大于Na2CO3处理后上升幅度,二者的差异达到极显著水平.研究发现,盐爪爪种子萌发对于低浓度中性盐(NaCl)胁迫具有较强的耐性和抗性,而在碱性盐(Na2CO3)的胁迫下其萌芽受到一定的抑制.     

Simulation of Potential Production and Optimum Population Quantitative Indices for the Second Hybrid Rice

The article established the HDRICE model by modifying the structure of the ORYZA1 model and revising its parameters by field experiments. The HDRICE model consists of the modules of morphological development of rice, daily dry matter accumulation and partitioning, daily CO₂ assimilation of the canopy, leaf area, and tiller development. The model preferably simulated the dynamic rice development because of the thorough integration of the effects of temperature and light on the rates of rice development, photosynthesis, respiration, and other ecophysiological processes. In addition, this model has attainable grain yield in the test experiment that showed the potential yield of cultivar Xieyou 46 ranged from 11 to 13 tons ha⁻¹. Besides, the model was used to optimize the combinations of the transplanting date, seedling age and density for cultivar Xieyou 46 at Jinhua area, and the population quantitative indices to attain the potential yield such as maximum stems, effective panicles, filled grain number/leaf area, and so on. The result showed that the combination of transplanting date on July 25, seedling age of 35 days and base seedling density of 1.33×10⁶ha⁻¹ is the optimum combination for the second hybrid rice production in Jinhua County, China. And the maximum stems, the effective panicles, the filled grain per panicle, the peak of optimum LAI, LAI in later filling stage, and the filled grain number/leaf were 6.03×10⁶ha, 3.99×10⁶ha, 119.2, 8.59, 5–6, and 0.64, respectively.     

中华鳖的消化道指数和血液生化指标

主要测定了中华鳖的消化道指数及血液中几种重要酶的活性,并将胃、肠、胰重与体重进行回归分析。结果表明:消化道的重量随体重同步变化,回归分析表明二者的幂回归相关系数最高。中华鳖的乳酸脱氢酶、肌酸激酶、碱性磷酸酶、谷-草转氨酶和谷-丙转氨酶的活性分别是人上限值的3.4、11.2、4.8、6.6和2.4倍,且谷-草转氨酶、谷-丙转氨酶和碱性磷酸酶的活性两两正相关。     

装烟密度对密集烘烤过程中烟叶主要生理指标的影响

采用河南农业大学设计的电热式温湿自控密集烤箱,对不同装烟密度和变黄温度下烟叶的淀粉酶、过氧化物酶(POD)、抗坏血酸过氧化物酶(AAO)及叶绿素的动态变化作了探索性研究。结果表明:整个烘烤过程中,装烟密度为5 5～6 5kg/m3的处理烟叶淀粉酶、过氧化物酶、抗坏血酸过氧化物酶的活性相对较高,叶绿素含量最低     

对甘肃省7个无公害蔬菜产地认证县(市) 土壤重金属含量的评价

甘肃省7个无公害产地认证县(市)土壤重金属总砷、总汞、总铅、总铬的检测结果表明,总砷含量为10.05~16.35mg/kg、总汞为0.006~0.230mg/kg、总铅5.39~50.49mg/kg、总铬58.17~187.51mg/kg,4种重金属含量均符合NY5010-2002标准要求,表明以上所抽检7个县(市)的土壤质量较好,符合无公害蔬菜产地环境质量标准要求。     

五味子GAP基地环境质量评价

采用国家规定的环境质量及其分析方法标准,对吉林博维五味子GAP种植基地规划区环境空气、土壤环境和水质资源进行了评价.结果表明:吉林博维五味子GAP种植基地规划区大气质量标准达到GB 3095-1996的2级标准,土壤环境达到GB 15618-1995的1级标准,水资源达到GB 5084-92的1类标准.吉林博维五味子GAP种植区环境质量良好,符合绿色药材栽培的环境质量要求.     

玉米蚜种群的空间动态

应用不同的聚集指标对玉米蚜种群的空间动态进行分析。结果表明 ,玉米蚜在玉米田始终成聚集分布 ;选择受密度影响较小的聚块性指标 M/X 的值 ,描述了玉米蚜种群空间格局的时序动态 ,表明玉米蚜聚集强度有明显的规律 ,呈现高—低—高的趋势。综合玉米蚜种群数量的消长规律、环境因子的变化等信息 ,对其空间图式及其时序动态特征的成因进行了分析