Combined effect of deficit irrigation and potassium fertilizer on physiological response,plant water status and yield of soybean in calcareous soil

A 2-year field experiment (2013 and 2014) was conducted in calcareous soil (CaCO₃ 19.2%), on soybean grown under three irrigation regimes 100%, 85% and 70% of crop evapotranspiration combined with three potassium (K₂O) levels (90, 120 and 150 kg ha^?1). The objective was to investigate the complementary properties of potassium fertilizer in improving soybean physiological response under water deficit. Plant water status (relative water content RWC, chlorophyll fluorescence F_v/F₀ and F_v/F_m), had been significantly affected by irrigation or/and potassium application. Potassium improved growth characteristics (i.e. shoot length, number, leaf area and dry weight of leaves) as well as physiochemical attributes (total soluble sugars, free proline and contents of N, P, K, Ca and Na). Yield and yield water use efficiency (Y-WUE) were significantly affected by irrigation and potassium treatments. Results indicated that potassium application of 150 and 120 kg ha^?1 significantly increased seed yield by 29.6% and 13.89%, respectively, compared with 90 kg ha^?1 as average for two seasons. It was concluded that application of higher levels of potassium fertilizer in arid environment improves plant water status as well as growth and yield of soybean under water stress.     

Effect of drought pretreatment before anthesis and post-anthesis waterlogging on water relation,photosynthesis, and growth of tomatoes

The effect of drought preconditioning before anthesis and post-anthesis waterlogging on water relation, photosynthesis, and growth was studied in tomatoes. Tomatoes were grown in pots and exposed to four treatments, whereby the plants were irrigated to 80% field capacity in T1 (control) and T2, 70% of the control (T3), and 50% of the control (T4). Drought was maintained for 30 days from 14 days after transplanting (DAT), and then the plants under T2, T3, and T4 were subjected to waterlogging at 60 and 80 DAT and lasted for 2 days. The results showed that drought pretreatments induced a decrease in leaf water potential, leaf insertion angle, photosynthetic rate, and transpiration rate. The stomatal closure and epinasty observed in response to drought pretreatment represented adaptive mechanisms to the followed waterlogging. The soil redox potential, photosynthetic rate, stomatal conductance, and transpiration rate of un-pretreatment were dramatically decreased by post-anthesis waterlogging; however, T3 was found to effectively enhance tolerance to a waterlogging event by decreasing leaf insertion angle and increasing photosynthetic rate, stomatal conductance, and transpiration rate. Fruit quality and yield were deteriorated considerably by waterlogging. However, T3 caused less damage to fruit quality and yield by post-anthesis waterlogging compared to T2.     

深色有隔内生真菌柱孢顶囊壳对玉米幼苗生长、光合作用及耐铅能力的影响

Dark septate endophytic (DSE) fungi are ubiquitous and cosmopolitan,and occur widely in association with plants in heavy metal stress environment.However,little is known about the effect of inoculation with DSE fungi on the host plant under heavy metal stress.In this study,Gaeumannomyces cylindrosporus,which was isolated from Pb-Zn mine tailings in China and had been proven to have high Pb tolerance,was inoculated onto the roots of maize (Zea mays L.) seedlings to study the effect of DSE on plant growth,photosynthesis,and the translocation and accumulation of Pb in plant under stress of different Pb concentrations.The growth indicators (height,basal diameter,root length,and biomass) of maize were detected.Chlorophyll content,photosynthetic characteristics (net photosynthetic rate,transpiration rate,stomatal conductance,and intercellular CO2 concentration),and chlorophyll fluorescence parameters in leaves of the inoculated and non-inoculated maize were also determined.Inoculation with G.cylindrosporus significantly increased height,basal diameter,root length,and biomass of maize seedlings under Pb stress.Colonization of G.cylindrosporus improved the efficiency of photosynthesis and altered the translocation and accumulation of Pb in the plants.Although inoculation with G.cylindrosporus increased Pb accumulation in host plants in comparison to non-inoculated plants,the translocation factor of Pb in plant body was significantly decreased.The results indicated that Pb was accumulated mainly in the root system of maize and the phytotoxicity of Pb to the aerial part of the plant was alleviated.The improvement of efficiency of photosynthesis and the decrease of translocation factor of Pb,caused by DSE fungal colonization,were efficient strategies to improve Pb tolerance of host plants.     

水分胁迫对金露梅叶片水势、光合特性和水分利用效率的影响

为解决青海高寒区绿化植物的栽培驯化问题,并为金露梅栽植的科学管理及高寒区水资源有效利用提供理论基础,以2年生金露梅幼苗为研究对象,通过盆栽方法人为控制土壤水分条件,测定不同土壤水分条件下金露梅苗木的光合生理特征,研究金露梅光合生理特性及其与土壤水分的相互关系.结果显示:1)金露梅凋萎系数为4.02％左右;2)土壤水分对金露梅叶水势及光合作用的影响具有阈值现象,净光合速率最大时土壤含水量为20.83％,水合补偿点为4.38％,水分利用效率最大时土壤含水量为13.82％;3)在砂壤土条件下,金露梅生长最适宜的土壤水分环境为8.33％ ～12.71％,此范围内既可以维持植物基本的生长所需,又可以最大程度提高水分利用效率;4)青海地区在金露梅盛花期(7月),在无降雨的情况下,每2～3周补充一次水分能维持金露梅较好生长.2～3周的持续干旱所造成的伤害在灌水后可逐渐恢复,但连续1个月无任何供水会使金露梅死亡.     

兰州南北两山主要水土保持造林树种荧光特性比较

在兰州南北两山,以自然分布的柽柳（Tamarix chinensis）、柠条（Caragana intermedia）、红砂（Reaumuria soongorica）为研究对象,在生长季利用PAM-2000便携式叶绿素荧光分析仪对其叶绿素荧光参数及其环境因子进行了测定。结果表明:3种植物叶片的初始荧光（Fo）、最大光化学转换效率（Fv/Fm）、光化学淬灭系数（qP）、非光化学淬灭系数（qN）、光合有效辐射（PAR）、叶温（TMP）的日变化较明显。其中Fv/Fm和qP均呈反正态分布曲线日进程,在13:00强光下降低至最低值;Fo,qN,PAR和TMP则呈正态分布曲线日进程,在13:00达到最大值。3种植物的Fv/Fm在中午呈降低趋势,在13:00左右达到的最低值分别为0.778（柽柳）,0.676（柠条）和0.65（红砂）,表明均发生光抑制现象,但红砂受到的胁迫最大。     

长期定位试验中氮肥与磷肥有机肥联合施用通过刺激根的生长增加玉米产量和养分吸收

Imbalanced application of nitrogen (N) and phosphorus (P) fertilizers can result in reduced crop yield, low nutrient use efficiency, and high loss of nutrients and soil nitrate nitrogen (NO₃^--N) accumulation decreases when N is applied with P and/or manure; however, the effect of applications of N with P and/or manure on root growth and distribution in the soil profile is not fully understood. The aim of this study was to investigate the combined effects of different N and P fertilizer application rates with or without manure on maize (Zea mays L.) yield, N uptake, root growth, apparent N surplus, Olsen-P concentration, and mineral N (Nmin) accumulation in a fluvo-aquic calcareous soil from a long-term (28-year) experiment. The experiment comprised twelve combinations of chemical N and P fertilizers, either with or without chicken manure, as treatments in four replicates. The yield of maize grain was 82% higher, the N uptake 100% higher, and the Nmin accumulation 39% lower in the treatments with combined N and P in comparison to N fertilizer only. The maize root length density in the 30--60 cm layer was three times greater in the treatments with N and P fertilizers than with N fertilizer only. Manure addition increased maize yield by 50% and N uptake by 43%, and reduced Nmin (mostly NO₃^--N) accumulation in the soil by 46%. The long-term application of manure and P fertilizer resulted in significant increases in soil Olsen-P concentration when no N fertilizer was applied. Manure application reduced the apparent N surplus for all treatments. These results suggest that combined N and P fertilizer applications could enhance maize grain yield and nutrient uptake via stimulating root growth, leading to reduced accumulation of potentially leachable NO₃^--N in soil, and manure application was a practical way to improve degraded soils in China and the rest of the world.     

Effects of boron excess in nutrient solution on growth,mineral nutrition,and physiological parameters of Jatropha curcas seedlings

Jatropha curcas L. has recently attracted the attention of the international research community due to its potential as a biodiesel crop. In addition, its high resistance to drought and salinity is well known. Under arid and semiarid conditions, boron (B) concentrations in irrigation water can be higher than desired when water from industry, urban areas, or desalination is used. However, the growth and physiological responses of J. curcas plants to B excess in the irrigation water are unknown. Therefore, a greenhouse experiment was conducted to study the effects of B excess in the nutrient solution (0.25, 2, 4.5, and 7 mg L^–1 B, applied as H₃BO₃) on plant growth, mineral concentration in the different plant tissues, photosynthesis, water relations, chlorophyll fluorescence, chlorophyll concentration (as SPAD values), and composition of carbohydrates. Plant growth decreased with increasing B concentration in the nutrient solution; growth reduction was higher for roots than for leaves or stems. The B concentration increased in all plant tissues, in the following order: leaf > root > stem. These data indicate that the roots of J. curcas are more sensitive to B toxicity than the leaves and that B has restricted mobility inside these plants, accumulating mainly in the basal and middle leaves via the transpiration stream. Increasing B concentration in leaves decreased the A_CO2 and the stomatal conductance, but the leaf water parameters were not affected. The data for chlorophyll concentration and chlorophyll fluorescence indicated that nonstomatal factors were involved in the A_CO2 decline, whereas decreases in the parameters of PSII photochemistry due to B toxicity suggest that there was structural damage in chloroplasts. There was also a general tendency for a decrease in nonstructural carbohydrates in all plant tissues, possibly due to the decline in A_CO2. With excess B, the concentrations of K and Mg increased in leaves due to a decrease in the growth, while a typical antagonistic effect between B and P was evident from the P concentration decrease in leaves. In summary, J. curcas should be considered a B‐sensitive plant, as a leaf B concentration of 1.2 mg (g dw)^–1 caused a growth decline of approximately 30%.     

粉垄耕作对红壤理化性质及红薯产量的影响

为改善红壤板结状况,缓解红壤区季节性干旱对作物的胁迫,本研究在江西省选择发育于第四纪红黏土的典型红壤设置传统旋耕15 cm(RT)和粉垄耕作20 cm(FL20)、30 cm(FL30)、40 cm(FL40)等4种耕作处理,通过监测土壤耕层厚度、容重、水分、养分的变化及红薯产量,以期揭示粉垄耕作对红壤理化性质和红薯产量的影响。结果表明:与RT处理相比,FL30和FL40处理显著增加了耕层厚度,降低了土壤容重,提高了土壤饱和导水率;粉垄耕作显著提高了降雨后土壤水分下渗速度、下渗量、下渗深度以及耕层土壤储水量,并导致干旱期土壤含水量的增幅大于湿润期。粉垄耕作导致土壤氮、磷等养分下移,形成"上减下增"的分布格局,与RT处理(23.10 t/hm2)相比,粉垄耕作20～40 cm(FL20、FL30和FL40)处理还提高了鲜薯产量89%～117%。因此,粉垄耕作显著改善了旱地红壤物理性质,改变了土壤养分在耕层中的分布,并有效调蓄了土壤水分合理分配,产能提升效果显著。     

再生水灌溉对草坪草生长速率、叶绿素及类胡萝卜素的影响特征

为节约城市清洁水源,扩大再生水利用力度,确保高质量的草坪,以草地早熟禾为研究对象,探讨了不同灌溉水源及再生水灌溉不同水分梯度下草坪草生长速率及叶绿素的变化特征。试验采用7种水分处理：清水适宜灌、混合水适宜灌、再生水充分灌、再生水适宜灌、再生水轻微干旱胁迫、再生水中度干旱胁迫、再生水重度干旱胁迫,灌水下限分别70%fc(田间持水量)、70%fc、80%fc、70%fc、60%fc、50%fc、40%fc,灌水定额相同。研究表明：不同灌溉处理下草坪草生长速率差异明显,再生水灌溉促进了草坪草的生长,草坪草生长速率与供水量成正相关;再生水灌溉下草坪草叶绿素及类胡萝卜素含量显著高于清水适宜灌处理下草坪草叶绿素及类胡萝卜素含量,而再生水灌溉草坪草叶绿素及类胡萝卜素含量在处理间差异不显著。     

生物强化有机土壤添加物结合石膏促进碱性土壤上睡茄的生长

Limited availability of organic matter is a problem to sustain crop growth on sodic soil. Organic soil amendments are a costeffective source of nutrients to enhance crop growth. A field study was conducted to evaluate the effect of an organic soil amendment bioaugmented with plant growth-promoting fungi(SF_(OA) ) in combination with gypsum on soil properties and growth and yield attributes of Withania somnifera, one of the most valuable crops of the traditional medicinal system in the world, on a sodic soil at the Aurawan Research Farm of CSIR-National Botanical Research Institute, Lucknow, India. The SF_(OA) used was prepared by pre-enriching farm waste vermicompost with plant growth-promoting fungi before mixing with pressmud and Azadirachta indica seed cake. The application of SF_(OA) at 10 Mg ha~(-1)after gypsum(25.0 Mg ha~(-1)) treatment significantly(P 0.05) increased root length(by 96%) and biomass(by 125%) of Withania plants compared to the control without SF_(OA) and gypsum. Similarly, the highest withanolide contents were observed in leaves and roots of Withania plants under 10 Mg ha~(-1)SF_(OA) and gypsum. Combined application of SF_(OA) and gypsum also improved physical, chemical and enzymatic properties of the soil, with the soil bulk density decreasing by 25%, water-holding capacity increasing by 121%, total organic C increasing by 90%, p H decreasing by 17% and alkaline phosphatase, β-glucosidase, dehydrogenase and cellulase activities increasing by 54%, 128%, 81% and 96%, respectively, compared to those of the control. These showed that application of the SF_(OA) tested in this study might reclaim sodic soil and further support Withania cultivation and results were better when the SF_(OA) was applied after gypsum treatment.     

黄土旱塬区平衡施肥下不同土壤耕作模式的蓄水纳墒及作物增产增收效应研究

【目的】黄土旱塬半湿润易旱区是典型的雨养农业区,多数一年一熟或两年一熟制,冬小麦和春玉米是该区主要的粮食作物,平衡施肥是主要的施肥方式。多年研究和生产实践证明,建立与不同作物轮作方式相配套的土壤轮耕技术体系,可以为作物生长发育创造良好的土、 肥、 水、 气、 热的土壤环境条件,保持农田生态健康发展,促进作物增产增收。本文在当地平衡施肥条件下,通过多年耕作模式定位试验,研究在平衡施肥条件下,不同土壤耕作模式对休闲期和作物生育期0200 cm土层蓄水纳墒状况、 作物产量及其经济效益的影响,为黄土旱塬半湿润易旱区建立在一定肥力水平下与作物轮作体系相配套的土壤轮耕模式提供理论依据。【方法】选择位于黄土旱塬半湿润易旱区腹地的陕西省合阳县甘井镇一年一熟旱作冬小麦春玉米轮作田为试验区,采用免耕、 深松和翻耕3种土壤耕作方法组成4种土壤轮耕模式,即: 翻耕免耕翻耕免耕(RT1); 深松翻耕深松翻耕(RT2); 免耕深松免耕深松(RT3); 免耕翻耕深松免耕(RT4); 以连年翻耕(CK1)、 连年深松(CK2)和连年免耕(CK3)为对照,通过连续4年(2007~2011年)定位试验,研究平衡施肥条件下的7种土壤耕作模式对冬小麦春玉米轮作田0200 cm土层土壤贮水量、 土壤水分含量、 作物籽粒产量、 水分利用效率(WUE)和经济效益的影响。【结果】 1)在土壤休闲期,RT3模式下0200 cm土层土壤贮水量最高,其次是RT2。与对照组相比,4种轮耕模式0200 cm土层土壤贮水量均高于CK1; RT3显著高于CK3,但与CK2差异不显著。0200 cm土层土壤剖面含水量,亦以RT3模式最高。2)在冬小麦生育期,0200 cm土层土壤贮水量和土壤含水量,RT3和CK2模式的较高。3)在春玉米生育期,0200 cm土层土壤贮水量和土壤含水量RT3和CK3较高。4)不同耕作模式的作物籽粒产量、 水分利用效率(WUE)和经济效益,以RT2和CK2模式最高。四年平均结果RT2处理较CK1、 CK2和CK3处理增产10.2%、 3.6%和17.1%,增收23.6%(P0.05)、 6.8%(P0.05)和28.3%(P0.05),提高WUE 9.7%(P0.05)、 4.3%和18.6%(P0.05)。【结论】年际间轮流进行深松和翻耕(RT2)处理,虽然其在土壤蓄水保墒效应方面略低于年际间轮流进行免耕和深松(RT3)和连年深松(CK2)处理,但可获得最佳增产增收效果和最高水分利用效率; 连年深松能够增加水分入渗,保护土壤,增加蓄水能力,但产量和经济效益不如RT2处理,也是该区比较适宜的耕作方法。根据实际状况,在平衡施肥条件下的一年一熟作物轮作区,应推荐深松翻耕的轮耕或连年深松的耕作模式。     

土壤改良剂对土壤紧实度及燕麦生长状况的影响

研究了不同土壤改良剂(聚丙烯酸钾,聚丙烯酰胺,腐殖酸钾,聚丙烯酸钾十腐殖酸钾,聚丙烯酰胺十腐殖酸钾)对土壤紧实度及燕麦生长状况的影响.结果表明,各改良剂处理均能减小土壤紧实度,表现为:聚丙烯酸钾十腐殖酸钾＞聚丙烯酰胺十腐殖酸钾＞聚丙烯酸钾＞聚丙烯酰胺＞腐殖酸钾＞对照,土壤紧实度均随着土壤深度增加而增加;土壤改良剂对燕麦株高和干物质量具有显著的提高作用,复配处理株高优于其他单施处理;土壤改良剂处理下籽粒产量均显著高于对照,其中聚丙烯酸钾十腐殖酸钾和聚丙烯酰胺十腐殖酸钾籽粒产量较其他处理高,分别为4 694.2和4 566.9 kg/hm2,较对照增产21.66％和18.36％,生物产量的增产效果表现同籽粒产量;各土壤改良剂处理水分利用效率均显著高于对照,其变化趋势与产量变化趋势一致,复配处理效果更佳.     

氮钾水互作对玉米苗期植株生长及钾素吸收的影响

采用盆栽试验方法探讨了氮钾水互作对玉米苗期植株生长及养分吸收的影响。结果表明,水分适宜能明显增加玉米植株株高和干物重,水分适宜条件下玉米株高和干物重较水分亏缺条件的分别增加7.8%和13.8%。增施氮肥能显著增加玉米植株株高和干物重,水分适宜条件下中氮水平的玉米株高和干物重分别较低氮水平的增加10.4%和8.7%,而水分亏缺条件下株高和干物重均随施氮水平的增加而明显增加;水分亏缺条件下,中高量施钾能显著增加玉米植株干物重。水分适宜条件下增施氮肥能明显促进玉米对钾素的吸收,在水分适宜和亏缺条件下,不同氮水平的玉米钾素吸收均随施钾水平的增加而显著增加。     

南佛罗里达州温室条件下番茄生长和养分吸收模型的验证

The Soil and Water Assessment Tool(SWAT) has been widely used throughout the world to model crop growth and nutrient uptake in various types of soils.A greenhouse experiment was performed to validate the process equations embedded in SWAT for describing the growth and nutrient uptake of tomatoes in south Florida.The scaled growth curve of greenhouse-grown tomatoes was in close agreement with the theoretical model for field conditions,with the scaling factors being the maximum canopy height and the potential heat units.Similarly,the scaled leaf area index(LAI) growth curve and the scaled root depth curve for greenhousegrown tomatoes agreed with the SWAT functions,with the scaling factors being the maximum LAI and maximum root depth.The greenhouse experiment confirmed that the growth of biomass is a linear function of the intercepted photosynthetically active radiation.The fractions of nutrients in the plant biomass under greenhouse conditions were found to be on the order of 60% of those fractions observed in the field.Values of the initial P distribution(0.2 mg kg -1),initial ratio of mineral stable P to mineral active P(50:1),and initial ratio of humic N to humic P(2.4:1) were determined from soil measurements and can be used for field simulations.The conventional saturation-excess model for soil-water percolation was used to predict the movement of water in the top 10 cm of the greenhouse containers and the results agreed well with measurements.     

水肥耦合对番茄光合、产量及水分利用效率的影响

为研究大棚膜下滴灌灌溉上限与施肥量耦合对番茄光合、产量及水分利用效率的影响,以金鹏1号番茄为试材,按照二元二次正交旋转组合设计原理,建立了光合与产量指标的数学模型,分析了水肥两因子的耦合效应。试验结果表明,所建模型达到显著水平;水对光合的影响大于肥,对产量的影响小于肥,水肥对光合和产量的耦合分别存在显著的负效应和正效应;光合速率随灌溉上限的上升表现出明显的上升趋势,超过一定范围后开始下降;不论灌溉上限高低,光合速率均随施肥量的增加表现出先降低后升高的趋势,变化趋势缓慢;番茄的产量随灌溉上限和施肥定额的增加而显著增加,超过一定范围后产量逐渐降低。得出合理的灌溉施肥指标:灌溉下限为田间持水量的50%,灌溉上限为田间持水量的80%~82%,施肥N 313.75~439.75 kg/hm2、P2O5156.55~219.19 kg/hm2、K2O 313.75~439.75 kg/hm2。此时,番茄的产量达到124 t/hm2、水分利用效率达到43.2 kg/m3。     

The effect of zeolite applications on yield components and nutrient uptake of common bean under water stress

In this study, the effects of different zeolite doses (Z₀:0, Z₃:30, Z₆:60, Z₉:90, and Z₁₂:120 t ha^?1) and water levels (I₅₀: 0.50, I₇₅: 0.75, and I₁₀₀:1.00) on yield, quality, and nutrient absorption of common bean were evaluated under arid conditions in Karapinar Konya, Turkey, in 2011 and 2012. The experiment was carried out in a split-plot design with three replications. The results showed that in each treatment different doses of zeolite together with changes in the rate of irrigation levels effected yield and yield components. Water use efficiency was also affected by zeolite and irrigation treatments. The highest yields, 4777 and 4114 kg ha^?1, respectively, were obtained from the Z₉I₁₀₀ application in 2011 and 2012. During the experimental years, water consumptions at the same treatment were determined 451 and 468 mm, respectively. In addition to this, zeolite treatments affected the contents of N, K, Zn, Mn, and Cu in leaf samples (p < 0.05). These nutrient levels increased with raising zeolite doses.     

Influence of municipal compost on temperature, water, nutrient status and the yield of maize in a temperate soil

Abstract. Composted domestic waste was applied either as a mulch or was incorporated into the topsoil. Mulching reduced the seasonal midday soil temperature ranges from between 14 °C and 27.5 °C to between 14 °C and 26 °C, averaging a 0.6 °C fall. However, at sub-optimal temperatures for maize production under the temperate conditions of South East England, the difference may be critical. Compost mulch also improved soil-water conservation in an average year, but not in a very dry year. Compost application increased soil-available N, but increased K uptake was considered to be more important for crop yield than either N additions or the effect on retained soil water. Overall, compost applied as a surface mulch, or incorporated into medium-textured soils in the south and east of England increased crop yield.     

Long term crop management effects on soil organic carbon,structure, and water retention in a cropland soil in central Ohio,USA

The objective of this study was to determine 13‐year management effects on soil properties between a corn–soybean (Zea mays–Glycine max) cropping system (CSRS) and vegetable production systems (VPS) on a soil in central Ohio. Three treatments included in the VPS were: (1) addition of wood chips, (2) permanent raised beds (PRB) with black polyethylene film (20 μm thick), and (3) bare soil surface (BSS). Additionally, (4) animal manure was applied in all CSRS and VPS treatments except for the wood chips (WCP) added plot in the VPS. Research data from the study show that relatively more soil organic carbon (SOC) stock in the 0–20 cm soil depth of the BSS treatment (100.6 Mg ha^?1) was primarily due to differences in the type of soil amendments applied. For example, composted poultry manure was applied in the BSS and PRB plots, compared with input of fresh dairy manure mixed with straw being applied in the CSRS. Furthermore, soil management practices that aided in avoiding or reducing soil compaction (i.e., PRB or application of WCP in the surface) resulted in the overall improvement in soil structure and water retention, compared with that under chisel and disc ploughing done in the CSRS. The highest plant available water capacity (1.79 cm) was observed in the CSRS compared with 0.97 cm under BSS and PRB plots. These trends suggest that the type and amount of animal manure is critical to increasing SOC stocks in intensively cultivated VPS and CSRS in central Ohio, while also improving soil structure and water retention.     

镉胁迫下生物炭与锌/钾叶面肥促进烟草生长降低镉富集的协同效应

[目的]生物炭和叶面肥在单独调控重金属胁迫条件下植物生长及重金属离子吸收方面的应用价值已被一些研究证实,然而它们在土壤重金属镉污染修复中的耦合效应及其机制尚不十分清楚。烟草为镉易富集植物,研究生物炭和锌/钾叶面肥单施或联合施用对烟草生长和镉富集特性的影响,为镉污染土壤的修复及烟草安全生产提供理论依据。[方法]采用盆栽模拟轻度土壤镉污染胁迫试验,供试烟草品种为‘中烟100’。设置6个试验处理:对照(CK)、土施生物炭20 g/kg(B)、喷施0.5%ZnSO4叶面肥(Zn)、喷施0.5%KH2PO4叶面肥(K)、生物炭+喷施ZnSO4叶面肥(B+Zn)、生物炭+喷施KH2PO4叶面肥(B+K),每个处理重复8次。将烟草分割为根、茎、下部叶(从下到上1~5片)、中部叶(6~10片)、上部叶(11~15片)5部分。测定株高、生物量、丙二醛含量(MAD)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性、烟株各部位的镉含量,计算了镉富集和转运系数,分析了土壤中镉形态的变化。[结果]1)单独施用叶面肥较单独施用生物炭更有利于增强镉胁迫下叶片的抗氧化性能,促进烟株生长。与B处理相比,Zn和K处理的MDA含量分别降低12.8%和15.1%,POD活性分别增加32.2%和29.9%,CAT活性分别增加25.5%和18.2%(P<0.05),Zn和K两处理之间的抗氧化酶活性无显著差异(P>0.05)。单独施用生物炭较单独施用叶面肥更有利于降低土壤中镉的生物有效性。与Zn和K处理相比,B处理的土壤弱酸提取态镉含量分别降低19.0%和19.3%,可还原态镉含量分别降低22.3%和23.9%(P<0.05)。单独喷施叶面肥对土壤镉形态无显著影响(P>0.05)。2)生物炭和叶面肥配施具有叠加效应,且B+Zn处理对促进镉胁迫下烟株生长和减少烟株镉吸收方面效果大于B+K处理。与CK、B、Zn处理相比,B+Zn处理的株高分别增加52.8%、25.9%和11.8%,地上干重分别增加146%、89.1%和45.3%,SOD活性分别增加29.8%、19.7%和11.0%,POD活性分别增加94.0%、64.1%和24.1%,CAT活性分别增加183.8%、90.9%和52.2%,烟株根镉含量分别减少53.9%、25.2%和31.6%,茎镉含量分别减少74.5%、53.9%和63.7%,上部叶镉含量分别减少63.1%、18.8%和40.1%,中部叶镉含量分别减少63.6%、27.7%和35.3%,下部叶镉含量分别减少63.8%、34.1%和46.9%,烟株镉生物富集系数分别降低64.4%、31.0%和48.4%,镉生物转运系数分别降低33.3%、20.2%和28.5%,土壤中弱酸提取态镉含量分别降低19.5%、7.5%和19.0%,土壤中还原态镉含量分别降低22.9%、2.0%和20.8%,土壤中可氧化态镉含量分别增加62.5%、5.6%和54.6%,土壤中残渣态镉含量分别增加206.9%、10.7%和174.7%。与B+K处理相比,B+Zn处理的烟株地上干重增加18.3%,上部叶、中部叶、下部叶镉含量分别减少8.4%、13.9%和16.9%,镉生物富集系数和转运系数分别降低20.8%和8.5%。[结论]在镉污染胁迫下,土施生物炭可以降低土壤中镉的生物有效性,减少烟草的吸收。叶面喷施锌、钾肥可以提高烟草植株的抗氧化性能,促进烟株生长。生物炭配合叶面肥具有明显的协同作用,降低烟草中镉的运转系数和富集系数的效果显著高于锌/钾叶面肥单独施用。在本试验条件下,生物炭配合喷施硫酸锌的效果好于生物炭配合喷施磷酸二氢钾,可作为提高烟草生产安全及土壤镉污染修复的一项有效措施。