Allelopathic effect of four weed species extracts on germination, growth and protein in different varieties of Glycine max (L.) Merrill

Allelopathic effect of Ageratum conyzoides L., Cynodon dactylon (L.) Pers., Parthenium hysterophorus L., and Solanum nigrum L. were examined on seed germination, seedling growth, total protein content and protein profile on Ankur, Bhatt, Bragg, PK -416, PS-1042 and Shilajeet varieties of soybean (Glycine max (L) Merill). Aqueous extracts of weeds (10% w/v) showed both inhibitory and stimulatory influence on percent seed germination and seedling growth in different varieties of soybean. On the basis of per cent reduction in different parameters, the variety Bragg and PS-1042, and Shilajeet were resistant and susceptible respectively to different weed extracts, and among weed extracts, S. nigrum was most effective followed by P. hysterophorus compared to others. The total protein content (mg/g f wt.) in different varieties was increased with all the weed extracts except Bragg with C. dactylon and P. hysterophorus, PS-1042 with A. conyzoides and Shilajeet with C. dactylon, in which it was decreased. The protein banding pattern in different varieties not only differ between control and treatments but also among treatments. The order of susceptibility of different varieties with different weed extracts followed the order: Ankur > PK-416 > Bhatt > Shilajeet > Bragg and > PS-1042.     

Effect of weed extracts on seedling growth of some varieties of wheat

Allelopathic effect ofAvena fatua L., Cyperus rotundus L., Polygonum hydropiper L., and Solanum nigrum L. were examined on seedling growth of certain commonly used varieties of wheat (Triticum aestivum L.) in the Tarai region of U.P. state. The weed extracts inhibited the length of plumule in all the varieties (100%) with Solanum and it was in 12 (92%), 10 (77%) and 06 (46%) varieties with Polygonum, Avena and Cyperus, respectively. In radicle length, it was in 92% with both Polygonum and Solanum; and 85% and 69% of the varieties with Avena and Cyperus, respectively. However, all the four weed extracts reduced the dry weight of plumule, radicle and total seedling in all the varieties (100%) of wheat except in HD--2329 with Cyperus, in which it was positive. The percent reduction (percentage of control) was more than 50% in 92%, 77%, 54% and 39% of the varieties, respectively with Solanum, Polygonum, Avena and Cyperus. Among the weed extracts, the inhibitory effect on seedling growth in different varieties followed the order: Solanum > Polygonum > Avena and > Cyperus. On the basis of the present results, UP--2003 and WH--542 followed by PBW--226, Sangam and HD--248 were more susceptible to all the four weed extracts compared to the rest of the varieties of wheat.     

入侵藤本薇甘菊的耐盐能力

薇甘菊Mikania micrantha Kunth为原产中南美洲的入侵藤本植物,现已在全球热带和亚热带地区照成严重的生态问题。野外观察发现薇甘菊已在珠三角沿海植被中滋生。为揭示薇甘菊的耐盐能力及其对滨海盐生植被的潜在危害性,分别对薇甘菊种子、根系和茎干在不同盐度胁迫下的响应进行了测定。在珠三角地区采集了薇甘菊3个批次的种子,并选取珠江三角洲6种常见植物（菊科假臭草Eupatorium catarium、藿香蓟Ageratum conyzoides、野茼蒿Crassocephalum crepidioides、鬼针草Bidens pilosa、翅果菊Pterocypsela indica和旋花科小花假番薯Ipomoea triloba）作为对照,测定了它们在不同NaCl盐度（质量分数）胁迫下的萌发率和幼苗生长;为揭示薇甘菊种子是否可由海水传播,将薇甘菊和对照植物假臭草、藿香蓟和鬼针草在不同盐度条件下浸泡不同时间后解除胁迫再观测其种子萌发率;为确定薇甘菊能否在滨海盐土中无性繁殖,分别对薇甘菊的根系和茎干在盐水浸泡下的植株生长进行了测定。研究结果表明：1）总体而言,薇甘菊3个种群在≤0.6%盐度胁迫下的种子萌发率均与对照组无显著差异,个别种群的这一阈值可高达1.5%,明显高于其他对照植物;同一盐度胁迫条件下,薇甘菊幼苗根系和苗高生长受抑制程度明显低于对照植物。2）即使经高达3.0%盐度胁迫浸泡长达12 d后,薇甘菊、藿香蓟和假臭草种子的萌发率也没有受到显著影响,而鬼针草种子的萌发率有明显下降;四种植物受浸泡后萌芽的幼苗生长均正常。3）薇甘菊根系受0.5%盐度胁迫时没有植株死亡,但苗高增长仅为对照组的53.3%;根系在1.0%盐度胁迫下有95%的植株能存活至少25 d,但苗高增长仅为对照的18.9%;根系在≥1.5%盐度胁迫下薇甘菊无法存活。4）被清水浸泡的薇甘菊茎茎叶均能存活且在全部被浸泡的节上萌芽。当薇甘菊茎干受≥1.0%盐水浸泡时,受浸泡的叶片全部死亡,在1.0%、2.0%和3.0%盐度胁迫下受试茎第21天的死亡率分别为42.9%、40.9%和86.4%。以上结果表明薇甘菊对盐生生境具一定的适应能力,可能通过种子萌发或无性繁殖扩张的方式对滨海盐生植被构成威胁,应当引起重视。     

Allelopathic effects of weeds extracts against seed germination of some plants

This study investigated the allelopathic effects of various weeds extracts on seed germination of 11 crop species. Most of the weed extracts tested had inhibitory effects on seed germination of common bean, tomato, pepper, squash, onion, barley, wheat, and corn at different application rates as compared with the 10% acetone control. Chickpea seed germination was inhibited by extracts of Solanum nigrum L., Chenopodium album L., and Matricaria chamomilla L. (10%, 20% and 22.5%, respectively) at the end of 21 day incubation period. However, Glycyrrhiza glabra L., Sorghum halepense (L.) Pers., and Reseda lutea L. extracts stimulated chickpea seed germination at the rates of 95%, 94%, and 93%, respectively, compared to control. It was concluded that some of the weed extracts tested in this study could be used as inhibitor while others could be used as stimulator for the crops.     

Studies on seed germination and growth in weed species of rice field under salinity stress

An investigation was made to see the salt tolerance of 10 weed species of rice. Properly dried and treated seeds of weed species were placed on 9 cm diameter petridishes lined with Whatman No. 1 filter paper under 6 salinity regimes, viz. 0 (control), 4, 8, 16, 24 and 32 dS m(-1). The petri dishes were then kept in germinator at 25 +/- 1.0 degrees C and 12 hr light. The number of germinated seeds were recorded daily. The final germination percentage, germination index (GI), seedling vigour index, mean germination time and time for 50% germination were estimated. Root and shoot lengths of the weed seedlings were measured at 20 days after salt application and relative growth values were calculated. Results revealed that salinity decreased final germination percentage, seed of germination as measured by GI, and shoot and root length in all the species. Germination of most of the weed seeds was completely arrested (0) at 32 dS m(-1) salinity except in E. colona (12%) and C. iria (13.9%). The species C. iria, E. colona, J. linifolia and E. crusgalli showed better germination (above 30%) upto 24 dS m(-1) salinity level and were regarded as salt-tolerant weed species. J. linifolia, F. miliacea, L. chinensis and O. sativa L. (weedy rice) were graded as moderately tolerant and S. zeylanica, S. grosus and C. difformis were regarded as least tolerant weed species.     

会泽铅锌尾矿区自然生长的3种豆科植物铅锌耐性的研究

为了解会泽铅锌尾矿区自然发生的豆科植物对重金属的耐性,研究了该地区自然发生的3种豆科植物在Pb2＋/Zn2＋单盐和双盐胁迫下种子萌发及其幼苗生长的情况。研究表明：在本实验所设的浓度范围内,Pb2＋/Zn2＋单独胁迫时,对供试植物种子及幼苗的生长主要表现为抑制作用,除苕子（Vicia Cracca L.）外,金属离子的质量浓度越大抑制作用越强;Pb2＋/Zn2＋共同胁迫时出现复杂的交互作用。对于苕子的种子及幼苗的生长,Pb2＋/Zn2＋呈现明显的相互加强抑制作用;对于其它2种植物,当Zn2＋浓度在低质量浓度时,Pb2＋似乎对Zn2＋抑制有缓解作用,同样当Pb2＋浓度在低质量浓度时,Zn2＋似乎对Pb2＋抑制有缓解作用,但是当Pb2＋/Zn2＋高浓度时,Pb2＋/Zn2＋呈现明显的相互加强抑制作用。不论是单盐还是双盐,苕子对的耐性最强,其次为白三叶（Trifolium repens L.）,紫花苜蓿（Medicago sativa L.）最弱。会泽铅锌尾矿区重金属含量高是该区植被恢复的最大障碍,进一步研究植物对Pb2＋及Zn2＋的耐受性对于铅锌尾矿区的植被恢复有极其重要的意义。     

三叶鬼针草生物量分配与化感作用对大气温度升高的响应

全球气候变暖已经成为不容置疑的事实,同时外来入侵植物对入侵地的生态环境造成严重的危害,外来入侵植物可能对温度升高做出积极地响应。文章研究了不同温度（22、26和30℃）处理对入侵植物三叶鬼针草（Bidens pilosa L.）种子萌发、幼苗生物量分配及化感作用的影响,探讨三叶鬼针草对全球气候变暖的响应策略。结果表明;温度为22和26℃比30℃有利于三叶鬼针草种子的萌发。温度升高显著增加三叶鬼针草的株高、生物量和叶面积,三叶鬼针草幼苗增加对茎和叶的生物量投资。同时相同浓度的三叶鬼针草水浸提液对马唐（Digitaria sanguinalis（L.）Scop）和牛筋草（Eleusine indica（L.）Gaertn）的化感作用随着温度升高而增强。研究表明：温度升高促进了三叶鬼针草的生长,改变生物量分配模式同时增强了对受体植物的化感作用。温度升高可能是促进三叶鬼针草入侵的生态环境因子之一,未来全球气温变暖可能使其入侵加剧。     

豆科牧草对4种农田常见杂草和水稻化感作用的研究

采用室内生测试验评价了白三叶、紫花苜蓿和毛苕子等3种豆科牧草新鲜茎叶的水浸提液对狗牙根、稗草、马唐和牛筋草等4种农田常见杂草种子萌发和幼苗生长的化感作用。利用盆栽试验研究3种豆科牧草的茎叶按不同比例与土混匀后对水稻秧苗生长的影响。结果表明：供体豆科牧草茎叶的水浸提液对狗牙根、稗草、马唐和牛筋草等的萌发率和幼苗生长均有不同程度的抑制作用,且随着水浸提液质量浓度的增加其抑制作用增强。浸提液质量浓度为0.1 g.mL-1时,毛苕子对稗草种子萌发的抑制作用强于其它3种,抑制率达50.8%;毛苕子对牛筋草幼苗根的抑制作用最强,抑制率达59.9%;白三叶对稗草幼苗茎的抑制率达54.3%。同时将豆科牧草的m（新鲜茎叶）-m（土）为1%和2%时,对水稻的苗高和地上部分的生物量有促进作用,3%时则抑制了水稻的生长。研究表明：施用适量的豆科牧草可以促进水稻生长,同时可有效控制稻田杂草。     

Pollution level in distillery effluent and its phytotoxic effect on seed germination and early growth of maize and rice

The effluent from a Lucknow- based distillery (Mohan Meakin Distillery) was analyzed for physico-chemical and biological parameters of pollution and concentration of potentially toxic heavy metals (Cd, Cr, Ni and Zn) and the effect of the distillery effluent, as such and on 50% dilution with tap water was studied on seed germination and seedling growth of maize (Zea mays L.) and rice (Oryza sativa L.). The effluent was wine red in colour and highly acidic (pH approximately 55) and possessed decaying alcoholic smell. The effluent contained high values of different pollution parameters, particularly total solids, 3450 mgl(-1) (soluble plus suspended solids), alkalinity 1500 mgl(-1), biological oxygen demand (BOD, 1649 mgl(-1)) and chemical oxygen demand (COD, 2036 mgl(-1)). It had very low values of dissolved oxygen (DO, 0.34 mgl(-1)). The heavy metals (Cd, Cr, Ni and Zn) content, particularly the nickel concentration (0.029 mg l(-1)) was high. Use of the distillery effluent, even on 1:1 dilution with tap water inhibited germination and early seedling growth of maize and rice. In both maize and rice, more so in the former germination % of seeds, length of radicle and plumule and the fresh and dry weight of the seedlings were significantly reduced. The emerging leaves of the seedlings also developed visible effects of toxicity some of which resembled the symptoms of nickel toxicity. Our observations suggest that the effluent, as discharged from the distillery carry a heavy load of pollutants. Its discharge into the river Gomti poses a potential threat to the aquatic life, perticularly during the summer months when the water flow in the river is drastically reduced. The distillery effluentis also harmful for irrigating crops grown along the drain carrying it.     

高梁种子萌发成苗过程中水分需求的量化研究

用渗透势不同的聚乙二醇（ＰＥＧ）６０００模拟外界环境水分条件，对高梁不同品种的种子在萌动、萌发及成苗３个阶段水分需求的量化研究表明：种子的抗旱性随吸水进程的推进而减弱，种子在萌动、萌发及出士成苗的时间（ｔ）与外界环境水势（ｗ）之间存在着１／ｔ＝ａ＋ｂｗ的关系，据此推算不同品种在不同成苗阶段的需水阈值，发现不同品种在同一成苗过程中对环境水分条件的反应不同，抗旱性也不同．     

稻田土壤种子库研究进展

土壤种子库是指存在于土壤表面和土壤中全部存活种子的总和。稻田土壤种子库是地上杂草产生的根本来源。我国是一个水稻种植大国,目前关于稻田土壤种子库的研究还不够全面和深入。研究稻田土壤种子库对于防治稻田草害具有重要指导意义,同时也是种子库研究领域的一个重要补充。取样方法和取样时间是研究土壤种子库的关键所在。而萌发法是最常见的判定方法。关于稻田土壤种子库大小的结论相差很大,从103~105 m-2不等。稻田土壤种子库中的杂草主要有19科55种,一般的稻田可检出10科或20种左右。种子的垂直分布格局主要受耕作强度的影响。70%~80%甚至更多的杂草种子分布在0~10 cm。稻田土壤种子库由于萌发、捕食、衰老和种子散布等原因具有季节动态。轮作制度、耕作方式、不同施肥处理以及除草方式等对稻田土壤种子库有重要影响。连续多年的田间管理会使种子库的大小、分布和物种组成产生年际变化。目前,需要加强长期定位研究,扩大研究区域和研究内容,重点研究杂草种子的休眠萌发机制和种子命运研究,为杂草治理提供更准确的信息。     

模拟酸雨对外来入侵植物三叶鬼针草生长及化感作用的影响

外来入侵植物三叶鬼针草（Bidens pilosa L.）对我国华南地区生态系统造成严重危害,同时华南地区也是强酸雨分布区域。采用不同pH值（2.5,4.0,5.6）的模拟酸雨对三叶鬼针草种子和幼苗进行处理,测定其对种子萌发和幼苗生长的影响;室外模拟酸雨喷淋三叶鬼针草,生物测定三叶鬼针草叶片水浸提液对受体植物的化感作用的变化。结果表明：pH为4.0和5.6的酸雨处理后提高了三叶鬼针草种子的萌发率;pH为4.0的酸雨促进幼苗生长,增加幼苗苗高和生物量;而pH为2.5的酸雨抑制三叶鬼针草种子萌发率和幼苗生长。同时,pH 4.0和2.5酸雨增强了三叶鬼针草叶片水浸提液对受体植物的化感作用。研究表明：三叶鬼针草具有较强的耐酸能力,酸雨胁迫可能通过促进外来入侵植物三叶鬼针草的生长和提高化感潜力而有利于其进一步入侵。     

几种菊科入侵植物和非入侵植物的化感作用比较

以萝卜为受体,采用培养皿法比较研究了几种菊科入侵种和非入侵种的化感潜力。结果表明：入侵种和非入侵种都具有化感作用,且入侵种在高浓度下的化感抑制作用强度不一定都大于非入侵种。在0.2 g.mL-1浓度时,艾蒿和黄鹌菜的综合化感作用强度分别是小飞蓬的2.5和3.1倍;而紫茎泽兰和银胶菊则是小飞蓬的3.8和3.5倍。而不同植物浸提液对萝卜的不同检测指标影响不同。其中,紫茎泽兰对萝卜种子发芽和幼苗生长的影响主要表现为化感抑制作用。银胶菊和除0.025 g.mL-1外的黄鹌菜各浸提液都使萝卜种子萌发受较强的抑制,且抑制强度随浸提液浓度的升高而增大,而对幼苗生长则表现为＂低促高抑＂的规律。小飞蓬和苦荬菜对萝卜种子萌发和幼苗根长为抑制作用,但对其苗高和鲜质量为促进作用。除0.025 g.mL-1外,艾蒿对萝卜种子萌发和幼苗根长有较强的抵制,对其苗高和鲜质量则呈＂低促高抑＂的规律。     

Stress response to nanoplastics with different charges in Brassica napus L. during seed germination and seedling growth stages

● Higher concentrations of PS, PS-NH₂ and PS-SO₃H inhibited seed germination. ● PS, PS-NH₂ and PS-SO₃H influenced seedling growth in a dose-dependent manner. ● PS, PS-NH₂ and PS-SO₃H reduced essential nutrients uptake and plant quality. ● PS, PS-NH₂ and PS-SO₃H increased antioxidant enzyme activities and MDA content. ● Nanoplastic toxicity was related to surface charges. Nanoplastic pollution has become a significant problem in farmland systems worldwide. However, research on the effects of nanoplastics (NPs) with different charges on field crops is still limited. In our study, NPs with different charges, including unmodified polystyrene nanoplastics (PS), positively charged polystyrene nanoplastics (PS-NH₂), and negatively charged polystyrene nanoplastics (PS-SO₃H), were investigated for their impacts on seed germination and seedling growth of rape. The results showed that seed water uptake (after 12 h), seed germination, seed vigour, and relative root elongation were all significantly reduced under exposure to NPs (200 mg/L). Similarly, remarkable decreases in plant biomass (root weight, shoot weight), growth (root length, plant height), photosynthesis ability (chlorophyll a, chlorophyll b, carotenoids), essential nutrient uptake (Fe, Mn, Zn, Cu), and plant quality (soluble protein, soluble sugar, crude fibre content) of rape seedlings were also observed after exposure to NPs. Among the three kinds of NPs, PS-NH₂ showed stronger effects. Moreover, superoxide dismutase, peroxidase, and catalase activities of rape seedlings were changed, and the content of malondialdehyde was significantly increased under exposure to NPs. Furthermore, positively charged PS-NH₂ showed stronger effects on the phenotype, physiology, biochemistry, nutrient uptake, and plant quality of rape. Notably, a comprehensive toxicity evaluation revealed that PS-NH₂ had the strongest toxicity to rape. The present study provides important implications for the interaction and risk assessment of NPs and crops in soil-plant systems.     

Prediction of germination rates of weed species: Relationships between germination speed parameters and species traits

In fields, the timing of weed emergence flushes is mostly related to the timing and rate of seed germination, which depend on seed dormancy level, soil temperature and water potential conditions as well as soil tillage and crop sowing date. Seed germination parameters are essential in weed dynamics models to account for the effects of soil conditions on weed demography. Since these parameters are difficult to measure, our objective was to test the possibility of estimating them from easily accessible information. Seed germination parameters (germination lag-time, time to mid-germination and mid-germination rate) were measured or collected from the literature for 25 weed species with contrasted seed characteristics. Correlations were then searched for between these parameters and morphological, chemical and physiological seed traits as well as seed dormancy level. The dormancy level was positively correlated with speed of germination parameters. Earliness of germination was positively correlated with seed lipid content and the seed area to mass ratio. Germination was also earlier and faster in species with a high base temperature for germination. These relationships explained about half the observed variability in germination speed parameters but should be further tested before being used to predict the germination behaviour of weed species in the field in different seasons.     

Response in germination and seedling growth in Phaseolus mungo under salt and drought stress

The effect of salt and drought stress at the water potentials of-2, -4,-6and -8 bars induced by NaCl and PEG 6000 (Polyethylene glycol 6000) each, on germination and early seedling growth, were investigated for two varieties (PU-19 and Type-9). Electrical conductivity (EC) value of the NaCl solutions were 4.5, 8.8, 12.7 and 16.3 dS m(-1). Germination percentage, root and shoot length, and seedling fresh and dry weight were measured in the study. The objective was to determine genotypic differences among P. mungo varieties in terms of salt and drought stress and to determine factors (salt toxicity or osmotic stress due to PEG) inhibiting seed germination. The germination results revealed that the genotypes significantly differed for salt and drought stress. PU-19 appeared to be more tolerant to salt and drought stress comparable to var Type-9. Both NaCl and PEG inhibited germination and seedling growth in both the varieties, but the effects of NaCI compared to PEG was less on germination and seedling growth. All varieties were able to germinate at all NaCl levels without significant decrease in germination, while a drastic decrease in germination was recorded at -6 and -8 bars of PEG. It was concluded that inhibition in germination at equivalent water potential of NaCl and PEG was mainly due to an osmotic effect rather than salt toxicity.     

Impact of fertilizer factory effluent on seed germination, seedling growth and chlorophyll content of gram (Cicer aeritenum)

In the present study effect of fertilizer factory effluent on seed germination, seedling growth and chlorophyll content of gram (Cicer aeritenum) has been carried out, at different concentration of the effluent and time intervals. The effluent is alkaline in nature with strong ammonia odour. The germination percentage of seed, seedling growth and chlorophyll content showed a gradual decline with increase in effluent concentration. At 25% concentration of the effluent, growth promotion in terms of root, shoot length and increase in chlorophyll content recorded at 21 days. However, at higher concentrations of the effluent toxic effects were observed at 21 days. The study suggests that the effluent can be used safely for Cicer aeritenum cultivation, only after proper treatment and dilution.     

Performance of seed germination and growth of Vicia faba L. in fly ash amended soil

The performance of Vicia faba L. in soil amended by different concentrations of fly ash has been studied. The parameters considered are seed germination, growth behaviour and nodulation frequency of the plant. Results revealed that while fly-ash amendment to the soil improved the growth performance at initial stages with application of lower concentrations, it was inhibitory at higher exposure concentrations. Although there was no difference in survival rates, but the seedling growth was reduced in comparison to control plants. Fly ash delayed the nodulation as lesser number of nodules was recorded at higher amendments. Results suggested feasibility of growing V. faba in fly ash contaminated area.     

部分菊科入侵种种子(瘦果)的萌发能力和幼苗建群特性

对入侵种种子生物学各方面的了解有助于更好地预测入侵趋势和评估可持续管理的策略.研究通过对部分菊科入侵种种子(瘦果)进行的室内萌发实验和土壤埋藏实验,通过与相关研究的对比和分析,对这些入侵种的萌发能力和幼苗建群特性进行了研究.10个入侵种种子室内萌发实验的结果表明,在25℃、12h光照的情况下,除钻形紫菀和一年蓬以外,被研究的其它8个种的终萌发率超过了50%,而且都显示出早期快速萌发的特点.用SPSS的曲线拟合工具对10个种的累积萌发趋势进行了曲线回归分析,对应的最佳模型均为三次曲线方程.不同土壤埋藏深度下幼苗出苗实验的结果表明,菊科8个入侵种的种子在表土的出苗率均最高,随着覆土厚度的增加,种子的出苗率逐渐降低,当覆土厚度超过3 cm以上时,所有种子均不能出苗.种子在不同的埋藏深度的出苗情况与种子的大小有关,较大种子破土能力相对较强;种子在不同的埋藏深度的出苗情况与种子本身的萌发能力也相关.土壤埋藏期限的实验结果表明,随埋藏时期的增加,小蓬草、苏门白酒草和一年蓬3个人侵种种子的活力逐步降低,在土壤中埋藏12个月后,其活力分别为21.34%、18.15%和27.38%.这些入侵种较广的种子萌发温度适应范围和高萌发率为防除工作带来了困难.在生产上,可通过不同时期的翻耕、将种子深埋等措施减少这些入侵种的危害.     

水分管理对重金属在水稻根区及在水稻中积累的影响

选取了酸性矿山废水污灌区重金属污染水稻土,通过盆栽试验,研究了不同水分管理条件（60%最大田间持水量,80%最大田间持水量,最大田间持水量,前期淹水＋抽穗扬花期烤田,全生育期淹水）下水稻根际土壤及其不同器官（稻根、茎叶和籽粒）中As、Cd、Cu和Zn的含量变化。结果表明：土壤水分含量对水稻根际土壤中As、Cu和Zn的含量影响不大。但显著影响水稻不同器官对这3种元素的吸收积累。随着土壤水分含量的增加,水稻根、茎叶和籽粒中As的含量都显著增加;Cu的含量则逐渐减少;水稻茎叶中Zn含量也逐渐减少,但水稻根和籽粒中Zn含量则变化不明显。抽穗扬花期拷田能显著降低As在水稻中的积累,显著增加水稻茎叶中Zn的积累;但不影响水稻各器官中Cu,以及水稻根和籽粒中Zn的含量。此外,虽然这3种重金属在土壤中含量均超标,但在水稻籽粒中含量只有Zn全部超标,而Cu则都不超标,因此,农作物的超标情况并不直接与土壤的重金属超标相联系。