Effects of humic acids and herbicides,and their combinations on the growth of tomato seedlings in hydroponics

The morphology and length of roots and shoots of tomato (Lycopersicon esculentum Mill.) seedlings grown on a nutrient medium for fourteen days in a controlled environment chamber were apparently not affected, whereas the dry matter content of roots was significantly enhanced when 200 mg L^?1 of humic acid (HA) isolated from either a non-amended soil or a sewage-sludge-amended soil was present in the nutrient medium. In contrast, the HA-like fraction isolated directly from the sewage sludge caused, under the same conditions, extensive alterations of tomato morphology and a significant reduction of the length and dry weight of both shoots and roots. The presence in the nutrient medium of the herbicides alachlor or imazethapyr at concentrations of 1 and 0.01 mg L^?1, respectively, caused a marked decrease of tomato root and shoot length and dry weight. Differently, the herbicide rimsulfuron at a concentration of 0.01 mg L^?1 produced a slight decrease in shoot and root length and a slight increase in their dry weight. A combination of 200 mg L^?1 soil HA and each of the herbicides alachlor, rimsulfuron and imazethapyr at concentrations of 1, 0.01 and 0.01 mg L^?1, respectively, in the nutrient medium attenuated the growth depression of tomato shoots and roots observed in the presence of the herbicide alone. However, the simultaneous presence of sewage sludge HA and any herbicide in the nutrient solution caused negative synergistic effects on tomato growth. The volume of nutrient solution and the amount of electrolytes taken up by tomato plants during the growth experiments correlated highly significantly with the total plant dry weight. Tomato seedlings induced a pH decrease in the nutrient medium in all treatments except in those where sludge-HA was present, either alone or in combination with any herbicide.     

Calcium and humic acid affect seed germination,growth, and nutrient content of tomato (Lycopersicon esculentum L.) seedlings under saline soil conditions

The effects of calcium and humic acid on seed germination, growth and macro- and micro-nutrient contents of tomato (Lycopersicon esculentum L.) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 2000 mg kg^?1) and calcium (0, 100, 200 and 400 mg kg^?1) were applied to growth media treated with 50 mg NaCl kg^?1 before sowing seeds. Seed germination, hypocotyl length, cotyledon width and length, root size, shoot length, leaf number, shoot and root fresh weights, and shoot and root dry weights of the plant seedlings were determined. Macro- and micro-nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of shoot and root of seedlings were also measured. Humic acid applied to the plant growth medium at 1000 mg kg^?1 concentration increased seedling growth and nutrient contents of plants. Humic acid not only increased macro-nutrient contents, but also enhanced micro-nutrient contents of plant organs. However, high levels of humic acid arrested plant growth or decreased nutrient contents. Levels of 100 and 200 mg kg^?1 Ca²⁺ application significantly increased N, Ca and S contents of shoot, and N and K contents of root.     

Phosphorus‐use efficiency by corn genotypes

Phosphorus (P) deficiency is a principal yield‐limiting factor for annual crop production in acid soils of temperate as well as tropical regions. The objective of this study was to screen nine corn (Zea mays L.) genotypes at low (0 mg P kg^‐1), medium (75 mg P kg^‐1), and high (150 mg P kg^‐1) levels of P applied in an Oxisol. Plant height, root length, shoot dry weight, root dry weight, shoot‐root ratio, P concentration in shoot and root, P uptake in root and shoot, and P‐use efficiency parameters were significantly (P<0.01) influenced by P treatments. Significant genotype differences were found in plant height, shoot and root dry weight, P uptake in root and shoot, and P‐use efficiency. Based on dry matter production and P‐use efficiency, genotypes were classified as efficient and responsive, efficient and nonresponsive, nonefficient and responsive, and nonefficient and nonresponsive.     

Root morphological traits related to phosphorus‐uptake efficiency of soybean,sunflower, and maize

Many of the plant acquisition strategies for immobile nutrients, such as phosphorus (P), are related to the maximization of soil exploration at minimum metabolic cost. Previous studies have suggested that soybean (Glycine max L.), sunflower (Helianthus annuus L.), and maize (Zea mays L.) differ in their P uptake efficiency. In this investigation we employed these three species to evaluate: (1) the effect of suboptimal P conditions on root morphological traits related to root porosity and fineness and (2) how these traits are related to P‐uptake efficiency. Opaque 25‐L plastic containers were used to grow plants hydroponically. The three species were compared under two P availability levels (low P and high P). Most of the observed responses were in the direction to favor P uptake under low‐P conditions. Compared to P‐sufficient plants, P‐stressed plants of the three species showed higher root‐to‐shoot ratio, specific root length, root porosity and root aerenchyma, and a lower root density. For example, P‐stress increased root porosity by a factor of 2.0, 1.4, and 1.4 in soybean, sunflower, and maize, respectively. Soybean and sunflower were the species with the highest P‐uptake efficiency, expressed as P uptake either per unit root biomass or length. The results demonstrate the central role of aerenchyma development in modifying root length per unit root biomass and, thus, reducing the root's foraging costs. Consequently, aerenchyma is suggested to be a possible mechanism for better P‐uptake efficiency.     

腐殖酸对NaCl胁迫下梭梭种子萌发及幼苗生长的影响

[目的] 探究腐殖酸对NaCl胁迫下梭梭种子萌发及幼苗生长的影响,为干旱矿区生态修复提供技术支持。[方法] 设置5个NaCl盐胁迫浓度,5个腐殖酸添加浓度,观测梭梭种子萌发以及幼苗生长指标,分析腐殖酸对梭梭种子萌发及其幼苗生长的耐盐性。[结果] 施用适量腐殖酸能显著提高种子萌发率,缓解梭梭种子萌发过程中的盐胁迫,促进初生根生长,降低盐胁迫对幼苗的伤害。在1.0 mol/L NaCl条件下,腐殖酸为700 mg/kg时缓解效果最好,与对照相比梭梭发芽率、发芽势、根长、幼根鲜质量和幼根干质量分别提高10%,11.12%,1.77 cm,4.84 mg和4.03 mg。[结论] 腐殖酸可作为干旱矿区生态修复中种子萌发和幼苗生长的一种盐渍土调节剂,具有较好的应用潜力。     

Effects of phosphorus and water stress levels on growth and phosphorus uptake of bean and sorghum cultivars

Primary determinants of crop production in arid/semiarid regions are lack of moisture and infertility, especially phosphorus (P) deficiency or unavailability. The effects of P and water stress (WS) levels on shoot and root dry matter (DM), leaf area, root volume, total root length, and shoot and root P concentrations and contents were determined in two bean [Phaseolus acutifolius Gray, cv ‘Tepary #21’ ("drought‐resistant") and P. vulgaris L., cv “Emerson’ ("drought‐sensitive")] and two sorghum [Sorghum bicolor (L.) Moench, cv SA7078 ("drought‐resistant") and ‘Redlan’ ("drought‐sensitive")] cultivars grown in nutrient solution. Plants were grown with different levels of P (20 and 100 μM for bean and 20, 80, and 160 μM for sorghum) when seedlings were transferred to nutrient solution, and WS levels of 0, 13.8, and 1 6.4% polyethylene glycol (PEG‐8000) introduced after plants had grown in solution 23 days (bean) and 31 days (sorghum). All growth traits were lower when bean and sorghum plants were grown with WS and low P. Growth traits were higher in cultivars grown with high compared to low P regardless of WS. Root P concentration and content and shoot content, but not shoot P concentration, were lower when bean plants were grown with WS compared to without WS. Tepary #21 bean had higher shoot DM, leaf area, total root length, and shoot P concentration than Emerson when plants were grown with WS at each level of P. Sorghum shoot and root P concentrations were higher as P level increased regardless of WS, and WS had little effect on shoot P concentration, but root P concentration was higher. Contents of P were similar for SA7078 and Redlan regardless of P or WS treatment, but SA7078 had greater P contents than Redlan over all P and WS treatments. “Drought‐resistant”; cultivars generally had better growth traits, especially total and specific root lengths, than “drought‐sensitive”; cultivars.     

NODULATION,NITROGENASE ACTIVITY,AND DRY WEIGHT OF CHICKPEA AND PIGEON PEA CULTIVARS USING DIFFERENT BRADYRHIZOBIUM STRAINS

Chickpea [Cicer arietinum (L.)] and pigeon pea [Cajanus cajan (L.) Millsp.] were grown outside in large clay pots from 1992 to 1995 in Edmond, Oklahoma. Plants were studied to evaluate nodulation, nitrogenase activity, and shoot dry weight (DW) of ‘ICCV-2’ and ‘Sarah’ chickpea inoculated with multistrain, TAL 1148, and TAL 480 Bradyrhizobium, as well as ‘Georgia-1’ and ‘ICPL-87’, pigeon pea inoculated with multistrain TAL 1127, and TAL 1132 Bradyrhizobium. Following wheat [Triticum aestivum (L.) emend. Thell.] harvests in the spring, legumes were planted in the summer and harvested at three successive dates during the following months. Leaves and stems from remaining plants were incorporated into the soil after the last harvest. Across year, chickpea measurements were sensitive to temperature and precipitation whereas pigeon pea measurements were sensitive to length of growing season as well as climate. Pigeon pea consistently demonstrated higher nitrogen-fixing capacity and shoot DW compared with chickpea. Nodule and shoot DW of both species increased with plant age whereas nodule count and nitrogenase activity generally increased with plant age and leveled off or decreased at flowering. Sarah chickpea demonstrated higher nodule count and nodule DW than ICCV-2, as did the Georgia-1 pigeon pea compared with ICPL-87. Shoot DW of Georgia-1 pigeon pea was generally higher than that of ICPL-87. Multistrain inoculum improved nodulation and shoot DW of chickpea, and TAL 1127 improved nodulation of pigeon pea compared with other treatments. These results indicate that specific chickpea and pigeon pea cultivars, along with appropriate Bradyrhizobium strains, may improve nitrogen fixation and DW of these species.     

Influence of humic acid on water retention and nutrient acquisition in simulated golf putting greens

Humic substances are frequently applied to creeping bentgrass ( Agrostis palustris Huds.) on golf putting greens to improve turf health and are marketed to enhance nutrient acquisition and possibly aid in retaining water in drought prone environments, but information on the role of humic substances in increasing soil water retention is limited. Additionally, it is difficult to separate the beneficial effects of nutrients and other ingredients added to commercial humic formulations from the effects of the pure humic substance. In our study, pure humic acid, tannic and citric acids were added to simulated creeping bentgrass putting greens. The organic acids were applied at normalized carbon rates of 250 mg C per litre by watering solutions through an automated irrigation system. Volumetric water content (VWC) and irrigation frequency, shoot and root growth, and tissue nutrient concentration of the turf were measured. None of the organic acid treatments improved water retention in the simulated greens. The humic acid-treated greens required more frequent irrigation than the untreated greens indicating that they were drying out more quickly. In addition, the addition of humic acid did not result in an increased tissue concentration of nutrients in the creeping bentgrass, top growth or dry shoot mass compared with the other treatments. However, creeping bentgrass root length was greater in the greens treated with humic acid compared with the untreated control.     

Relationships between shoot and root characteristics of white clover cultivars differing in response to phosphorus

Root dry weight and the relationship between shoot and root characteristics for 119 white clover (Trifolium repens L.) cultivars and breeding lines were examined at five (40, 120, 200, 400, and 500 mg P/kg soil) phosphorus (P) levels. There were significant (P<0.01) differences among cultivars for root dry weight and root/shoot ratio. Instantaneous root/shoot ratio decreased with increasing P supply up to 200 mg P/kg, and then increased again from 400 to 500 mg P/kg soil. Allometric analysis indicated that root growth relative to shoot growth increased with increasing P supply. There was a significant (P<0.01) cultivar x P level interaction such that for the cultivars, the root/shoot ratio was either unaffected, increasing, or decreasing with increasing level of P supply. However, root/shoot ratio appeared to be unrelated to the functions used to describe the P response of the 119 cultivars studied. Shoot characters such as dry weight, leaf number, and stolon length were most closely correlated with root dry weight at the moderately low P levels of 120 and 200 mg added P/kg, where average P response was 9 and 24% of yields at 500 mg P/kg soil, respectively, rather than at the higher P levels. Root/shoot ratio was significantly correlated (r>0.6) with root dry weight over all P levels but not with any of the measured shoot characters (‐0.2> r <0.3).     

铅胁迫对19个品种草坪草种子萌发和幼苗生长的影响

用浓度分别为0(对照)、200、400、600mg/L的Pb2+分别处理19个品种草坪草的种子,测定了供试种子发芽势、发芽率、幼苗根长、苗长、鲜重、叶绿素含量、丙二醛含量等7项指标,比较19个品种草坪草生长初期耐铅性的强弱。结果表明：在不同浓度Pb2+胁迫下,有的品种种子发芽势、发芽率、幼苗根长、苗长、鲜重、叶绿素含量呈先上升后下降的变化趋势,有的品种这些指标呈下降变化趋势;有的品种丙二醛含量呈先下降后上升的变化趋势,有的品种丙二醛含量呈上升的变化趋势。通过聚类分析,Pb2+400 mg/L胁迫下将19个草坪草品种的耐铅性分为3 类;耐铅性强的品种有热浪;耐铅性较强的有星火、回报、绿城、爱瑞3号、家园、美洲豹3号、3A、麦哲伦、自豪、里园2号等; 耐铅性弱的有晚霞、本特、橄榄球2号、高地、优异、优美、午夜、抢手股;并通过主成分分析进一步确定19个品种在Pb2+400 mg/L胁迫下耐铅性由强到弱的顺序为热浪＞星火＞爱瑞3号＞3A＞回报＞美洲豹3号＞绿城＞家园＞自豪＞里园2号＞麦哲伦＞晚霞＞本特＞橄榄球2号＞高地＞优美＞抢手股＞午夜＞优异。     

Interactions of mustard plants and soil microorganisms after application of sugarcane filter cake and pea residues to an Andosol

In a pot experiment using a strongly P‐fixing Andosol from Nicaragua, the effects of sugarcane–filter cake application on the growth of white mustard (Sinapis alba L.) were compared with those of ¹³C‐labeled pea residues. The application of pea residues led to a 50% increase and the application of filter cake to a 30% decrease in soil organic matter–derived microbial biomass C compared with the control. In contrast, the application of filter cake resulted in a four times higher content of substrate‐derived microbial biomass C than that of pea residues. The application of organic substrates generally increased microbial biomass N. Mustard growth led to significant increases in microbial biomass P in the control, but also in the organic‐amendment treatments, which always resulted in decreased microbial biomass C : P ratios. Mustard growth also led to increased contents of Bray‐1‐extractable P, but this increase was only significant in the filter cake treatment. The application of pea residues had no effect on the yield of shoot C, but a positive effect on the yield of root C in comparison with the nonamended control. In contrast, the application of filter cake significantly depressed yields of shoot C and root C, due to N immobilization, presumably due to the high concentration of lignin.     

Interactions between biomass production and ethylene biosynthesis in copper‐treated rice

Rice (Oryza sativa L.) plants were grown over a 30‐day‐period in nutrient solutions containing increasing copper (Cu) concentrations (0.002, 0.01, 0.05, 0.25, 1.25, and 6.25 mg/L). It was observed that in both root and leaf tissues the total activity of l‐aminocyclopropane‐l‐carboxylate synthase decreased at concentrations above 0.05 mg/L Cu treatment, whereas the total activity of the ethylene forming enzyme slightly increased until the 1.25 mg/L Cu treatment. In the root and leaf tissues, the 1‐aminocyclopropane‐l‐carboxylic acid concentrations decreased after the 0.05 mg/L and 0.01 mg/L Cu treatments, respectively, whereas the ethylene production decreased in both tissues after the 0.05 mg/L Cu treatment. It is proposed that excess Cu in both root and leaf tissues decrease the conversion of S‐adenosylmethionine to 1‐aminocyclopropane‐l‐carboxylic acid through the inhibition of the total l‐aminocyclopropane‐l‐carboxylate synthase activity. The concomitant effect of this inhibition on adventitious root formation and leaf senescence is evaluated.     

Genotypic variation of potato for phosphorus efficiency and quantification of phosphorus uptake with respect to root characteristics

Potato (Solanum tuberosum L.), an important food crop, generally requires a high amount of phosphate fertilizer for optimum growth and yield. One option to reduce the need of fertilizer is the use of P‐efficient genotypes. Two efficient and two inefficient genotypes were investigated for P‐efficiency mechanisms. The contribution of root traits to P uptake was quantified using a mechanistic simulation model. For all genotypes, high P supply increased the relative growth rate of shoot, shoot P concentration, and P‐uptake rate of roots but decreased root‐to‐shoot ratio, root‐hair length, and P‐utilization efficiency. Genotypes CGN 17903 and CIP 384321.3 were clearly superior to genotypes CGN 22367 and CGN 18233 in terms of shoot–dry matter yield and relative shoot‐growth rate at low P supply, and therefore can be considered as P‐efficient. Phosphorus efficiency of genotype CGN 17903 was related to higher P‐utilization efficiency and that of CIP 384321.3 to both higher P‐uptake efficiency in terms of root‐to‐shoot ratio and intermediate P‐utilization efficiency. Phosphorus‐efficient genotypes exhibited longer root hairs compared to inefficient genotypes at both P levels. However, this did not significantly affect the uptake rate and the extension of the depletion zone around roots. The P inefficiency of CGN 18233 was related to low P‐utilization efficiency and that of CGN 22367 to a combination of low P uptake and intermediate P‐utilization efficiency. Simulation of P uptake revealed that no other P‐mobilization mechanism was involved since predicted uptake approximated observed uptake indicating that the processes involved in P transport and morphological root characterstics affecting P uptake are well described.     

育苗基质添加腐植酸促进番茄穴盘苗生长改善生理特性

【目的】以番茄为材料,研究穴盘育苗基质中腐植酸添加对幼苗生长及硝酸还原酶活性、光合参数等的影响,为培育优质壮苗和腐植酸的应用提供参考依据。【方法】番茄育苗基质以草炭、蛭石、珍珠岩按体积比4:3:2配成,其中腐植酸含量为54.5 g/L（约11.85%）,播种前在基质中分别添加折合纯腐植酸0（CK）、10 g/L（T1）、20 g/L（T2）、30 g/L（T3）、40 g/L（T4）,共5个处理,每处理3次重复,每个重复3个穴盘。待植株长到5叶1心（子叶展开后29~31天）时测定番茄幼苗的生长指标、根系活力、硝酸还原酶活性、光合色素含量、光合参数和叶绿素荧光参数。【结果】T1、T2、T3处理均显著提高了番茄幼苗的株高、茎粗,对番茄幼苗根干重的提高幅度大于地上部干重;T1、T2处理显著提高了根冠比和壮苗指数,T3处理与CK差异不显著;各生长指标均以T2处理表现最好,T4处理最差。T1、T2、T3处理显著提高了根系活力和硝酸还原酶活性,而T4处理二者明显降低。基质中适当提高腐植酸含量,可提高番茄幼苗叶片各种光合色素含量,但腐植酸含量过高,则会降低各光合色素含量。T1、T2、T3处理的Pn、Gs、Ci均显著高于CK,均以T2处理最高,T4处理的Pn、Gs显著低于CK,但其Ci高于CK;Tr表现为CK最高,随腐植酸添加量的增加,逐渐降低。T1、T2处理的Fo、NPQ均低于CK,且以T2处理的最低,T3、T4处理的均高于CK,且以T4处理的最高;各处理的Fv/Fm和ΦPSⅡ的大小顺序均为T2 > T1 > CK > T3 > T4,其中T1、T2处理显著高于CK,T3、T4处理则显著低于CK。【结论】番茄育苗基质中腐植酸在已含有54.5 g/L的基础上以添加20 g/L能够更好地促进番茄穴盘苗生长,改善其生理活动,对培育壮苗有更好的效果。     

黄腐酸添加量对低氮胁迫下小麦生长和根系形态的影响

【目的】黄腐酸(FA)是腐植酸中分子量较小、活性最大的组分,作为一种生物刺激素,FA可以促进植物生长,提高植株的抗逆性。研究黄腐酸不同添加量对低氮胁迫下小麦生长及根系形态的影响,为小麦减氮增效提供实践和理论参考。【方法】以小麦品种‘鑫华麦818’为材料进行了水培试验。将营养液氮浓度调节为硝态氮0.1 mmol/L模拟低氮胁迫(LN),并分别设置FA添加量0、30、60、90、120 mg/L,即LN-FA0、LN-FA30、LN-FA60、LN-FA90、LN-FA120,共5个处理;以正常供氮营养液(硝态氮4 mmol/L)为对照(NN)。分析了小麦根系形态、植株生物量、植株氮浓度、氮累积量、叶片氮代谢关键酶活性等指标。【结果】与LN-FA0相比,LN-FA30、LN-FA60、LN-FA90和LN-FA120处理的地上部生物量分别提高了16.31%、23.18%、26.75%和35.16%,LN-FA120的地上部生物量与正常氮处理已无显著差异;LN-FA30、LN-FA60和LNFA90总根长增加了35.00%～44.67%,根表面积增加了39.93%～95.42%,根体积增加了...     

Root‐growth characteristics contributing to genotypic variation in nitrogen efficiency of oilseed rape

A 3‐year field experiment was carried out to determine the significance of root‐growth characteristics contributing to N‐uptake efficiency of two oilseed rape (Brassica napus L.) cultivars differing in N efficiency. Two N treatments were applied, and the core and minirhizotron techniques were used to study root‐length density and number of living roots, respectively. Fertilizer‐N supply increased shoot dry matter, grain yield, total N uptake, and total soil N_min contents particularly in the top soil. Although significant differences occurred in all parameters between years, the interactions between years and cultivars were mostly not significant. Compared to cv. Capitol, the N‐efficient cv. Apex was characterized by a higher grain yield at N0 and a higher N uptake during reproductive growth. This genotype also had a higher root‐length density and more living fine roots particularly in the topsoil layer. Root growth of this genotype was especially high from beginning of shooting to beginning of flowering, while shoot growth and N uptake during vegetative growth were comparatively low. Our results suggest that N‐efficient cultivars can be characterized by a high investment in root growth during the vegetative stage with a comparatively slow shoot growth and N‐uptake rate until beginning of flowering, which, however, continues during reproductive growth. High root production only during reproductive growth seems to be less effective to achieve high N efficiency, because this may lead to a shortage of assimilates for seed filling. High root‐length density at vegetative stages may thus be advantageous for N uptake and reproductive growth and could be a useful morphological character for the selection and breeding of N‐efficient cultivars.     

Phosphorus efficiency of ornamental plants in peat substrates

A pot experiment was conducted to investigate factors contributing to phosphorous (P) efficiency of ornamental plants. Marigold (Tagetes patula) and poinsettia (Euphorbia pulcherima) were cultivated in a peat substrate (black peat 80% + mineral component 20% on a volume basis), treated with P rates of 0, 10, 35, 100, and 170 mg (L substrate)^–1. During the cultivation period, plants were fertigated with a complete nutrient solution (including 18 mg P L^–1) every 2 d. Both poinsettia and marigold attained their optimum yield at the rate of 35 mg P (L substrate)^–1 and the critical level of P in shoot dry matter of both crops was 5–6 mg g^–1. After planting, plant‐available P increased at lower P rates to a higher level for poinsettia than for marigold, but no significant change was observed at higher P rates. Balance sheet calculations indicated that at lower P rates more P was fertigated than was taken up by the plants. Root‐length density, root‐to‐shoot ratio, and root‐hair length of marigold were doubled compared to that of poinsettia. Root‐length density increased with crop growth, and 10 d after planting the mean half distance between roots exceeded the P‐depletion zone around roots by a factor of 3 and 1.5 for poinsettia and marigold, respectively. Thus, at this early stage poinsettia exploited only 10% of the substrate volume whereas marigold utilized 43%. Later in the cultivation period, the depletion zones around roots overlapped for both crops. Taking into account P uptake via root hairs, the simulation revealed that this was more important for marigold compared to poinsettia especially at low P‐supply levels. However, increase of P uptake due to root hairs was only 10%–20% at optimum P supply. For the two lower P levels, the P‐depletion profile around roots calculated for 10 d after planting showed that after 2 d of depletion the concentration at the root surface was below the assumed K_m value (5 μM) and the concentration gradient was insufficient to fit the demand. A higher content of plant‐available P in the substrate was observed for poinsettia compared to marigold in the treatment with P application adequate for optimum growth, because more fertigated P was accumulated during early stages of cultivation due to lower root‐length density of poinsettia. The observed difference of root morphological parameters did not contribute significantly to P‐uptake efficiency, since P mobility in the peat substrate was high.     

供磷水平对苗期小麦地上和地下部性状关联性的影响

【目的】磷素是植物生长发育过程中必需的大量元素之一,土壤磷水平的高低对植物地上部和地下部性状有着显著的影响。探究高、低磷水平对小麦地上和地下部性状变化以及地上和地下部性状相关性变化的影响,为研究不同磷环境对小麦生长的影响,选育适应不同磷环境的优良小麦品种提供参考。【方法】小麦品种和磷水平双因素盆栽试验在河北农业大学温室内进行,供试土壤有效磷含量为5.50 mg/kg。试验设置0和200mg/kg两个施磷水平;选用10个小麦品种。小麦分别在两个磷水平下生长35天后收获,测定小麦幼苗地上部性状（干重、相对生长速率、地上部磷吸收量、地上部磷含量和叶绿素含量）和根部性状（根干重、根长、根冠比、比根长、根直径、细根比例、根组织密度、根际土壤pH和酸性磷酸酶活性）。【结果】与高磷处理相比,低磷处理小麦地上部干重、地上部磷吸收量以及地上部磷含量分别显著降低了57.9%～72.2%、85.7%～89.8%、61.3%～71.7%,小麦根长、细根比例、根组织密度、根冠比以及比根长分别增加了50.9%～249.5%、32.5%～442.5%、–34.5%～400.0%、27.4%～198.9%、74.4%...     

Varietal tolerance to Zinc deficiency in wheat and barley grown in chelatorbuffered nutrient solution and its effect on uptake of Cu,Fe, and Mn

Tolerance to zinc (Zn) deficiency was examined for three wheat (Triticum aestivum L.) and three barley (Hordeum vulgare L.) varieties grown in chelator‐buffered nutrient solution. Four indices were chosen to characterize tolerance to Zn deficiency: (1) relative shoot weight at low compared to high Zn supply (“Zn efficiency index”), (2) relative shoot to root ratio at low compared to high Zn supply, (3) total shoot uptake of Zn under deficient conditions, and (4) shoot dry weight under deficient conditions. Barley and wheat exhibited different tolerance to Zn deficiency, with barley being consistently more tolerant than wheat as assessed by all four indices. The tolerance to Zn deficiency in the barley varieties was in the order Thule=Tyra>Kinnan, and that of wheat in the order Bastian=Avle>Vinjett. The less tolerant varieties of both species accumulated more P in the shoots than the more tolerant varieties. For all varieties, the concentrations of Mn, Fe, Cu, and P in shoot tissue were negatively correlated with Zn supply. This antagonism was more pronounced for Mn and P than for Cu and Fe. Accumulation of Cu in barley roots was extremely high under Zn‐deficient conditions, an effect not so clearly indicated in wheat.