Variability and Correlation between Exchangeable Sodium Percentage and Sodium Adsorption Ratio in Vertisols of Sudan

Vertisols in the Sudan occur under different climatic zones, ranging from arid in the north to tropical monsoon in the south, with rainfall varying from 150 mm to 1000 mm per annum. In this study, the exchangeable sodium percentage (ESP) was estimated from the sodium adsorption ratio (SAR); values of SAR and ESP for all identified soil series of Vertisols in the Sudan were extracted from the available data. These data were used to examine the variability in SAR and ESP in these soils using coefficient of variation (CV) as an index and then to regress ESP on SAR for the three master horizons (A, AC, C) and pooled data for all horizon. Curvilinear, linear, quadratic, and cubic equations were used to examine the relation between ESP and SAR. The significance of the F ratio and correlation coefficient was tested for individual equation. The soil series were then sorted out into saline and nonsaline, sodic and nonsodic, and the ESP was regressed on SAR once again. The equations used for the regression were curvilinear and first‐, second‐, and third‐degree polynomial equations. Then analysis of variance (ANOVA) was used to screen any significant difference between the estimated values of ESP (using these equations and USDA salinity laboratory equation) on one hand and the actual (measured) values of ESP. The results revealed that ESP and SAR are highly variable irrespective of depth despite slight decrease with depth. Furthermore, ESP is more variable than SAR in horizons A and AC but less variable in horizon C. The regression equations indicated that ESP might be reasonably estimated from SAR. However, different equations were appropriate for different horizons. Moreover, the result indicated that in most of the cases the relation between ESP and SAR better fits quadratic equations. But for simplicity, linear equations for all horizons could be used to estimate ESP from SAR.     

Distribution Characters of Absorption Nitrogen in Oilseed Rape (Brassica Napus L.) at Different Growth Stages

Two winter oilseed rape varieties grown in sand culture were labeled with ¹⁵Nitrogen (¹⁵N) at different growth stages to show the route of nitrogen (N) absorption, distribution, and transfer in oilseed rape (Brassica napus L.). Averaged over the two varieties, 84% of the N absorbed at the seedling stage, and 67% of the N absorbed at the stem elongation stage were distributed into the leaves. Of the N absorbed at flowering stage, 43% was distributed into the leaves and 36% into stems. However, 42.4% of the N absorbed at siliquing stage was directly found into the silique. The proportion of the N redistributed from vegetative organs into reproductive organs was 34%, 44%, 41%, and 32%, at seedling, stem elongation, flowering, and siliquing stages, respectively. The amounts of N transferred were 203, 326, 218, and 82 mg per plant, respectively. This corresponded to 65% of the total in the grain. The proportions of N lost after absorption were 24%, 11%, 12%, and 7% at the four growth stages, respectively. The amounts lost were 142, 79, 43, and 16 mg per plant, respectively. N absorbed at early growth stages in oilseed rape was mainly distributed to the leaves first, and then redistributed to the reproductive organs later. This route provided most of the N for the reproductive organs.     

重金属元素在湿地生态系统中的迁移与分配

为了解重金属元素在湿地生态系统中的迁移和分配特征,于2011年夏季采集了大庆市龙凤湿地土壤、水、芦苇、鱼等4种样品,采用原子吸收分光光度法测定其中Cu,Cd,Zn,Pb,As和Hg这6种重金属元素的含量水平,应用统计学方法分析了彼此之间的相关关系。结果显示,龙凤湿地环境质量状况良好,土壤重金属含量低于松嫩平原的平均值,水体环境质量低于地表水环境质量Ⅱ级标准;湿地中生存的动、植物对重金属的累积情况各不相同,鱼体重金属的富集情况为:Zn>Cd>Cu>As>Hg>Pb,而芦苇重金属的富集情况则为:Cd>Hg>Zn>Cu>As>Pb。分析表明,土壤重金属含量与植物、鱼体重金属含量之间均存在明显的正相关关系,而水、植物、鱼三者之间虽然也存在一定的正相关关系,但均未达到显著水平。     

Effects of Boron Stress on copper enzyme activity in tomato

Moderate B deficiency in plants has been reported to enhance Cu deficiency by keeping these plants in the vegetative growth stage. In this study, ascorbate oxidase activity was used as an index of the effect of B stress on Cu activity. When T3238FER (B‐inefficient) and Rutgers (B‐efficient) tomatoes (Lycopersicon esculentum Mill.) were grown in nutrient solutions at various B levels, B‐stressed plants had higher ascorbic acid oxidase activity than B‐sufficient plants. This activity was significantly higher in T3238FER than in Rutgers. Ascorbic acid oxidase activity may be directly or indirectly related to the role of B in plant growth and may be responsible for the more efficient use of B by Rutgers than by T3238FER tomato.     

不同类型红富士苹果对春季土施~(15)N-尿素的吸收、分配和利用特性研究

以15年生"惠民短枝"(短枝型)和"长富10"(普通型)红富士苹果/平邑甜茶(M.domesticaBorkh.cv.RedFuji/M.hupenensisRhed)为试材,研究其对春季土施15N-尿素的吸收、分配与利用特性。结果表明,盛花期短枝型和普通型红富士均以细根中吸收的氮素来源与肥料的比例(Ndff)值最高,分别为0.407%和0.286%,短枝型显著高于普通型;新梢旺长期和花芽分化期,根部吸收的15N优先向新生营养器官运转,短枝型红富士,除叶片外,其余各器官中Ndff值均高于普通型;果实膨大期和果实采收期,短枝型和普通型红富士均以果实中Ndff值最高,短枝型高于普通型;采收后,短枝型和普通型红富士均以粗根中Ndff值最高,分别为0.902%和0.792%,短枝型高于普通型。不同物候期短枝型和普通型红富士吸收的15N在各器官的分配率存在差异,盛花期贮藏器官15N分配率最高,两品种差异不显著;新梢旺长期和花芽分化期,短枝型和普通型红富士贮藏器官15N的分配率不断下降,15N主要向营养器官分配,短枝型低于普通型;果实膨大期和果实采收期短枝型和普通型红富士生殖器官成为新的分配中心,短枝型显著高于普通型;采收后15N向贮藏器官回流、积累,短枝型红富士贮藏器官能积累更多的营养物质。春季土施15N-尿素,随着物候期的推移,短枝型和普通型红富士对15N尿素的吸收利用率逐渐上升,采收后达到最高,分别为24.643%和16.311%;短枝型红富士氮素利用率普遍高于普通型。     

水稻对~(134)Cs的吸收和~(134)Cs在水稻-土壤中的分配

试验表明,水稻对~(134)Cs的吸收,孕穗期吸收速率最快;土壤理化性质不同,吸附~(134)Cs的能力有差异;不同生育期灌溉~(134)Cs溶液,水稻对其吸收量不同,离成熟期近,吸收得多;灌溉次数多和灌溉水中~(134)Cs活度高,水稻吸收的~(134)Cs也多。糙米经精白加工后,可使~(134)Cs的污染减少22.6—45.6％;~(134)CS在水稻各部位比活度大小的顺序为糠>根>稻草>谷壳>精白米;活度以稻草中最高,占水稻植株总活度的51.4％,糙米、根和谷壳分别占28.4％。11.8％和8.4％:~(134)Cs在土壤中移动很少,有95.1％集中在0—2.5cm的表土层内;~(134)Cs在水稻-土壤中的分配为6.1％:93.9％;K~+抑制水稻对~(134)Cs的吸收,K~+浓度与水稻中~(134)Cs比活度之间呈指数回归形式。     

基于激光衍射的土壤粒径测定法的评价与校正

为比较与评价激光法与吸管法测定土壤粒径分布的准确性,该文采用激光法与吸管法测定了23组来自中国13个不同省份或自治区土壤样本的粒径分布,将激光法与传统吸管法的测定结果进行比较,并在此基础上对激光法测定参数进行了修正。结果表明:1)与吸管法相比,激光衍射法低估土壤样品中的黏粒含量,其相对误差为36.33%;高估粉粒含量,其相对误差为36.51%;2)对吸管法与激光衍射法的实测结果进行线性关系分析表明,其中黏粒与粉粒的线性关系较好,决定系数分别为0.91,0.90;3)经过模型转换后,基于激光衍射法的土壤粒径分布结果的相对误差明显降低:黏、粉的相对误差分别降低至16.25%、12.83%,说明激光衍射法可以用于大规模不同类型的土壤粒径分析。该研究可为土壤系统化和规范化的对比研究以及建立基于激光衍射技术的土壤质地划分标准提供依据。     

聚光集热苦咸水蒸馏装置中含吸光颗粒水体的光吸收特性

传统太阳能蒸馏装置存在传热热阻大,传热换热环节多等缺陷,导致太阳能蒸馏装置热能利用效率低和淡水产量小,鉴于此,该文设计一种新型基于聚光集热的苦咸水蒸馏装置,利用抛物碟式聚光器将入射太阳光汇聚并直接在含有大量黑色多孔颗粒苦咸水体内完成光热转化,克服了传统太阳能蒸馏器光传输方向与热传输方向相反的缺点,减少了装置传热换热环节,使得聚光直接加热苦咸水蒸馏产水得以实现,该文对于装置中实现光热直接转化的水体光吸收特性展开试验测试和理论分析,借助光学积分箱对影响水体模拟受热温升阶段和沸腾蒸发阶段光吸收特性的吸光颗粒粒径、颗粒丰度及光程等因素展开研究。结果表明,含较小粒径吸光颗粒的水体光吸收特性较好,在模拟受热温升过程中,含粒径为0.5 mm颗粒的水体最大光吸收比比含有粒径为1.0 mm颗粒的水体增加9.0%,模拟受热沸腾过程中,丰度为6.7 g/L水体光吸收比是丰度为0.75 g/L水体的4.94倍,且水体光吸收比随沸腾程度呈指数函数变化规律。该研究结果为太阳能苦咸水蒸馏技术的热能高效利用提供参考。     

韶关地区6种阔叶树种幼林的凋落物持水特性研究

对3年生樟树(Cinnamomum camphora)、大叶女贞(Ligustrum Lucidum)、观光木(Tsoongioden-dron odorum)、山杜英(Elaeocar pus sylvestris)、乳源木莲(Manglietia yuyuanensis)和乐昌含笑(Michelia cha pensis)的幼林凋落物持水特性进行了研究.结果表明,各林地的凋落物最大持水量为乳源木莲林地＞乐昌含笑林地＞大叶女贞林地＞观光木林地＞樟树林地＞山杜英林地.林地凋落物的最大持水率呈现观光木林地＞乳源木莲林地＞乐昌含笑林地＞樟树林地＞山杜英林地＞大叶女贞林地.凋落物持水量和浸泡时间的关系及凋落物持水率与浸泡时间的关系按照对数方程变化,凋落物吸水速率与浸泡时间的关系按照负指数方程变化.