玉米幼苗根系形态对芘污染的响应

采用盆栽试验探讨了玉米（Zea mays L.）根系形态学参数（根质量长度、根质量面积、根质量体积、根平均直径及不同根直径等级分布）对不同浓度芘污染胁迫的响应。较低浓度芘可适当地刺激玉米的生长,高浓度芘处理抑制了玉米的生长,并且抑制作用随芘处理浓度的提高而增强;芘对玉米根系的影响要大于对茎叶的影响。不同浓度芘处理下玉米根系形态学参数发生了显著的变化,与对照相比,芘处理下根直径显著降低,根质量长度、根质量面积和根质量体积显著增大,且随芘处理浓度的提高其效应更显著。     

UV-B辐射对大豆和黄瓜幼苗某些生理特性的影响

在植物生长室中,ＵＶ－ Ｂ辐射明显降低黄瓜幼苗的根系活力,抑制程度随辐射时间的延长而增强．黄瓜和大豆幼苗的叶绿素和可溶性蛋白含量减少与ＵＶＢ辐射时间长短呈正相关,但是类胡萝卜素减少幅度不大．ＵＶＢ对Ｃｈｌｂ 的破坏较Ｃｈｌａ 严重,导致Ｃｈｌａｂ 比值增大．ＵＶＢ虽增加大豆幼苗的ＳＯＤ活性,但降低大豆幼苗的ＮＲ活性及其对温度变化的敏感性．分析认为,Ｃｈｌａｂ 比值和ＳＯＤ 活性升高,有助于植物对ＵＶＢ的适应     

The Influence of Mycorrhiza on Uranium and Phosphorus Uptake by Barley Plants from a Field-contaminated Soil (7 pp)

Background Recent studies indicated that arbuscular mycorrhizal fungi (AMF) play important roles in plant accumulation of uranium (U) from contaminated environments, but the impacts of fertilization practices on functioning of the symbiotic associations, which are crucial factors influencing plant nutrition and growth responses to mycorrhiza, have rarely been considered. Materials and Methods In a greenhouse experiment, a bald root barley mutant (brb) together with the wild type (wt) were used to test the role of root hairs and AMF in uranium (U) uptake by host plants from a U contaminated soil. Nil, 20 and 60 mg KH2PO4-P kg–1 soil were included to investigate the influences of phosphorus (P) fertilization on plant growth and accumulation of U. Results Dry matter yield of barley plants increased with increasing P additions and wt produced significantly higher dry weight than brb. Mycorrhiza markedly improved dry matter yield of both genotypes grown at nil P, whereas only brb responded positively to mycorrhiza at 20 mg P kg-1. At the highest P level, mycorrhiza resulted in growth depressions in both genotypes, except for the roots of wt. In general, plant P concentrations increased markedly with increasing P additions and in response to mycorrhiza. Mycorrhiza and P additions had no significant effects on shoot U concentrations. However, root U concentrations in both genotypes were significantly increased by mycorrhiza. On the other hand, shoot U contents increased with increasing P levels, while 20 mg P kg-1 stimulated, but 60 mg P kg-1 marginally affected the U accumulation in roots. Root length specific U uptake was moderately enhanced both by root hairs and strongly enhanced by mycorrhiza. Moreover, non-inoculated plants generally had higher shoot-root ratios of U content than the corresponding inoculated controls. Conclusion Our study shows that AMF and root hairs improves not only P acquisition but also the root uptake of U, and mycorrhiza generally decreases U translocation from plant root to shoot. Hence, mycorrhiza is of potential use in the phytostabilization of U contaminated environments. Perspectives The complex impacts of P on U accumulation by barley plants suggested that U behavior in mycorrhizosphere and translocation along the soil-fungi-plant continuum as affected by fertilization practices deserve extensive studies for optimizing the function of mycorrhizal associations for phytoremediation purposes.     

蚕豆根尖微核技术监测农药污染的研究

实验应用蚕豆根尖微核技术对农药２，４－Ｄ和甲胺磷进行诱变性研究，结果表明：农药２，４－Ｄ和甲胺磷达到一定浓度时即成为诱变污染物，能明显诱发蚕豆根尖微核率的增高，在一定范围内显示出较好的剂量效应关系，说明蚕豆根尖微核技术是监测环境污染的一种有效方法。     

贵州盘县老厂竹根水的成因分析

贵州省盘县老厂竹根水, 分布面积10 km2 左右, 砂岩和玄武岩的地质环境下大面积竹林的存在是其形成的生态环境条件,雨水经过竹林-土壤-岩石的水循环过程和由此引起的含水介质的元素迁移为其水质、水量的主要原因。竹根水具有广阔的开发前景,但需要进一步涵养水源和加强对水质的保护。     

土壤中不同老化时间的DDT对小麦根系的生物有效性

研究了水、正己烷、正己烷/丙酮ASE对土壤中不同老化时间的DDT的逐级提取量的差别及其与小麦根吸收的关系。结果表明,有机氯的水提量随老化时间增加而下降,正己烷提取量随老化时间增加而下降,正己烷/丙酮提取量随老化时间增加而上升。植物根吸收随老化时间增加而下降。根吸收与水提量没有确定关系,与正己烷提取量具正相关关系,与正己烷/丙酮提取量有负相关关系。正己烷提取量可被作为土壤有机氯DDT的有效态部分。     

Modelling the fate of organic chemicals in the soil plant environment: Model study of root uptake of pesticides

The fate of organic chemicals in the soil-plant-atmosphere environment and the governing processes were studied with a coupled dynamic soil transport and plant compartment model. Scenarios with applications of pesticides on sand and loam soils with chemical uptake in barley and wheat were used in the model calculations. Root uptake and concentrations in the plant compartments stem, leave and fruit were calculated for the pesticides terbuthylazine, isoproturon and carbofuran.

The effectivity of uptake from soils with different soil sorption coefficients had been shown for sand and loam soils. The processes degradation in plant and volatilization from leaves to atmosphere are especially effective for carbofuran and terbuthylazine. Although the concentrations in corn at harvest are lower than the maximum allowed concentrations, the peak concentrations in the course of the vegetation period are significantly higher (factor ≤ 200).     

根系分泌物及其在植物营养中的作用

论述了根系分泌物的种类和影响因素，根系分泌物在植物营养中的调节作用、异种克生作用，根系分泌物与根际微生物的相互作用。在铁胁迫条件下，许多高等植物都能产生一系列生理和形态方面的适应性反应，禾本科植物通过根际特定分泌物——麦根酸类物质来自动调节其体内的铁营养状况；在磷胁迫条件下，根系分泌的低分子有机酸种类主要有柠檬酸、草酸、酒石酸和苹果酸，它们在植物根际的富集能明显促进土壤中磷的释放，提高作物对磷的吸收，缓解植物的磷胁迫；在锌胁迫条件下，双子叶植物的根系分泌物对锌的活化作用不明显，而禾本科植物的根系分泌物可以活化石灰性土壤中难溶性锌。     

紫花苜蓿品种间根系发育过程分析

从根系发育角度分析了不同紫花苜蓿品种在甘肃黄土高原丘陵沟壑区的适应性．研究表明：品种间侧根发生总数差异较大，Ameristand201和Sandili均为14个，陇东苜蓿(Longdong)仅为6个，65％的侧根发生于营养生长阶段；品种间主根生长，根系体积、根系生物量的积累在各个生育期的表现分为3种类型，Ameristand201，Sandili，Ameri-graze401在整个生育期内的生长速率较快，且速率基本保持一致；陇东苜蓿，Derby，Sitel在整个生育期内生长速率较慢，但在盛花期(7月中旬)后，生长速率急剧增加；Goldenempress，Defi，Algonqiun介于前两者之间．从根系发育过程分析，Amefistand201，Sandili，Amerigraze401对黄土高原丘陵沟壑区的季节性降水反映相对迟钝，在干旱半干旱生境中具有较好的适应性．     

粉葛根腐病的病原鉴定

近年来发现一种严重为害粉葛块根的土传病害。经显微镜直接检查、病原菌分离培养观察、致病性测定及田间病害调查，初步鉴定该病为粉葛镰刀菌根腐病，病原菌为腐皮镰刀菌(Fusarium solani，属半知菌亚门真菌)；该病的发生是由于腐皮镰刀菌与植物线虫复合感染所致。该报道在中国尚属首例。