Bicarbonate Had Greater Effects Than High pH on Inhibiting Root Growth of Zinc‐Inefficient Rice Genotype

Abstract

Effects of bicarbonate (10 mM as NaHCO₃) and high pH (pH 8 buffered with HEPES) separately on root growth and accumulation of organic acids in the roots of zinc (Zn)‐efficient (IR36) and Zn‐inefficient (IR26) rice genotypes (Oriza sativa L.) were investigated in this study. The results indicated that shoot dry matter yields were decreased more by bicarbonate than by high pH for the Zn‐inefficient genotype, but not affected for the Zn‐efficient genotype. Root dry weights, especially root length, was significantly decreased by bicarbonate and high pH treatments for the Zn‐inefficient genotype, whereas was considerably enhanced by only bicarbonate treatment for the Zn‐efficient rice genotype. The reduction in root growth of the Zn‐inefficient rice genotype and the enhancement of root length in the Zn‐efficient genotype were greater when plants grown with bicarbonate than with high pH treatment. Accumulation of malate, citrate, and fumarate in roots of the two genotypes increased considerably due to both high pH and bicarbonate treatments, but to a greater extent for the Zn‐inefficient than for the Zn‐efficient cultivars. After an 8‐day treatment, more organic acids accumulated in the roots of the Zn‐inefficient genotype (IR26) when plants grown with bicarbonate than at high pH, but this was not the case for the Zn‐efficient genotype. The influence of root growth by bicarbonate appeared to be one of the major factors for the sensitivity of rice genotypes to Zn deficiency in calcareous soils. The greater inhibitory effect of bicarbonate than high pH on root growth of the Zn‐inefficient genotype might result from an excessive accumulation and inefficient compartmentation of organic acids, particularly citrate and malate, in the root cells.     

Zinc sorption–desorption by sand,silt and clay fractions in calcareous soils of Iran

Zinc sorption–desorption by sand, silt and clay fractions of six representative calcareous soils of Iran were measured. Sand, silt and clay particles were fractionated after dispersion of soils with an ultrasonic probe. Zinc sorption analysis was performed by adding eight rates of Zn from 6 to 120 μmol g^?1. For the desorption experiment, samples retained after the measurement of Zn sorption were resuspended sequentially in 0.01 M NaNO₃ solution and shaken for 24 h. Results indicated that Zn sorption by soil fractions increased in the order clay > silt > sand, and correlated negatively with CaCO₃ content and positively with cation exchange capacity (CEC) and smectite content. Results indicated that for all fractions, the Langmuir equation described the sorption rates fairly well. In contrast to sorption, Zn desorption from soil fractions increased in the order sand > silt > clay, and correlated positively with CaCO₃ content, CEC and smectite content. Results showed that parabolic diffusion and two constant equations adequately described the reaction rates of Zn desorption. In general, for all soils studied, the coarser the particle size, the less Zn sorption and more Zn desorption, and this reflects much higher risk of Zn leaching into groundwater or plant uptake in contaminated soils.     

时间和温度对活性炭与板栗壳吸附铜锌铅镉的影响

随着工业化和城市化进程的加快,废水排放引起的水环境重金属污染问题越来越突出,去除污水中的重金属成为水环境保护的重要内容之一。本文选取活性炭与板栗壳作为吸附剂,研究在不同的时间及温度下,这2种吸附剂对废水中的Cu2+、Zn2+、Pb2+、Cd2+的吸附性能影响。研究发现,活性炭作为吸附剂时,Cu2+吸附量最大是在0.5 h时,Zn2+是在3 h时,Pb2+和Cd2+则是1 h时;用板栗壳吸附时,Cu2+和Pb2+吸附量最大在1 h,Zn2+是在1 h时,Cd2+则是0.5 h时。吸附剂为活性炭或板栗壳,温度对Zn2+的吸附率影响都不大;吸附Cu2+时,活性炭受温度的影响大于板栗壳,其吸附率随温度的升高而减小;Pb2+和Cd2+的吸附受温度影响明显,均是40℃时吸附率较高,但板栗壳>活性炭,且Cd2+>Pb2+。     

锌硅肥对强筋小麦产量及品质的影响

增施锌硅肥对小麦有显著的减少小穗退化、降低空秕率作用,达到增加每穗粒数、提高产量的目的。过量增施锌硅肥对强筋小麦蛋白质、湿面筋、赖氨酸等营养品质有一定负效应,不利于强筋小麦营养品质的提高。生产上以施用腐殖酸锌硅肥37.5kg／hm2为宜。     

土壤Cd、Zn活度模型及其控制相研究

采用盆栽试验，探讨了植物吸收Cd、Zn总量与土壤Cd、Zn活度及植物吸收系数的关系。结果表明：在一定的浓度范围内，植物吸收Cd、Zn的总量与土壤Cd、Zn的活度及植物吸收系数的关系可由式Ycp=u[M^2 ]θ表达。实践中，可依据土壤Cd、Zn活度模型及植物对重金属元素的吸收特性，采取相应措施调控重金属在土壤-植物体系中的迁移。     

肉牛微量元素锌锰碘营养状况的评价

在云南省会泽县和昭通市进行了 6个不同阶段的肉牛微量元素补饲试验 ,添加补充料后 ,肉牛日粮、血浆和血清中微量元素Zn、Mn和日粮I、血浆蛋白结合碘 (PBI)含量均有不同程度的增加 ,部分理化指标有显著变化 (P <0 0 5 ) ,表明在农村传统饲养模式下 ,肉牛微量元素Zn、Mn营养充足 ,但至少缺乏微量元素I,添加易吸收Zn、Mn对肉牛生产性能有一定的促进作用     

日粮锌与维生素A的交互作用研究进展

综述了日粮锌(Zn)与维生素A(VA)代谢交互作用的研究进展。日粮低Zn会导致血清VA水平下降，其机制是日粮低Zn可通过限制生长速度、影响肝脏视黄醇结合蛋白的合成及影响乙醇脱氢酶的活性对VA代谢产生影响。日粮高Zn也可引起血清VA水平下降，但在日粮VA过量时，高Zn对VA代谢的影响较小，其机制尚不清楚。同时，日粮VA通过影响肝脏Zn结合蛋白的合成影响动物体内Zn的转运，VA对Zn吸收的促进效果等同于VD对Ca吸收的促进效果。     

猪苓菌丝液体培养及富锌研究

对猪苓（Polyporus umbellatus Fr.)菌丝进行了液体培养及富集锌研究。结果表明，在培养温度22℃，PH7．0，振荡速度150r/min。培养基中锌添加量为40mg/kg时，猪苓菌丝的生物转化量及菌丝体富锌率最高。     

在种母鸡按标准饲喂条件下雏鸡卵黄囊中钙、磷、锰、锌含量的探讨

从按NRC标准饲养的种母鸡所产种蛋新孵出的AA肉用雏鸡中随机选取80只(公母各半),测定卵黄囊中钙、磷、锰和锌的含量及其与出壳体重和卵黄囊重的相关回归关系。结果表明,雏鸡出壳体重为48.15±0.37g,卵黄囊重为7.50±0.16g,卵黄囊中钙、磷、锰、锌的含量分别为26.86±1 90mg、49.46±1.69mg、0.018±0.002mg、0.222±0.011mg。雏鸡卵黄囊重与出壳体重的相关和回归关系显著(P≤0.05,r=0.60,b=0.25),卵黄囊重对出壳体重的回归方程为:Y=0.25X-3.75,卵黄囊中锌和磷的含量与出壳体重的相关及回归关系显著(P≤0.05,r=0.60,b=0.25),卵苏囊 重对出体重的回归方程为y=0.25x-3.75。卵苏囊中锌和磷的含量与出壳体重的相关及回归关系显著(P≤0.05)r=0.22,0.37:b=0.067,1.69)。因此,可由出壳体重估测卵黄囊重,对通过出壳体重估测卵黄囊中锌和磷的含量,也获得较为满意的结果。     

内蒙古锡林浩特地区土壤-牧草-家畜系统中Cu、Fe、Zn、Mn、Mg、Se六种元素含量的分析

对内蒙古锡林浩特地区土壤，牧草，家畜（羊）被毛中6种元素含量进行了测定。结果表明：土壤硒含量于缺乏的临界水平；尖草，羊草及针草中锌含量低于羊正常生长对锌的需求数量，兔毛草及羊草中的硒的含量很低，不能满足其正常生长需要，被毛中硒含量低于临界值，提示羊群缺硒。