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1.
Global production of glyphosate-resistant (GR) soybean [Glycine max (L.) Merr.] continues to increase annually; however, there are no particular specific fertilizer recommendations for the transgenic varieties used in this system largely because reports of glyphosate effects on mineral nutrition of GR soybeans are lacking. Several metabolites or degradation products of glyphosate have been identified or postulated to cause undesirable effects on GR soybeans. In this work we used increasing glyphosate rates in different application on cv. ‘BRS 242 GR’ in order to evaluate photosynthetic parameters, macro- and micronutrient uptake and accumulation and shoot and root dry biomass production. Increasing glyphosate rates revealed a significant decrease in photosynthesis, macro and micronutrients accumulation in leaf tissues and also decreases in nutrient uptake. The reduced biomass in GR soybeans represents additive effects from the decreased photosynthetic parameters as well as lower availability of nutrients in tissues of the glyphosate treated plants.  相似文献   

2.
Glyphosate-resistant (GR) soybean [Glycine max (L.) Merr.] was developed by stable integration of a foreign gene that codes insensitive enzyme 5-enolpyruvylshikimate-3-phosphate synthase, an enzyme in the shikimate pathway, the target pathway of glyphosate. Application of glyphosate to GR soybean results in injury under certain conditions. It was hypothesized that if GR soybean is completely resistant to the glyphosate, injury could be caused by a metabolite of glyphosate, aminomethylphosphonic acid (AMPA), a known phytotoxin. Glyphosate and AMPA effects on one- to two-trifoliolate leaf stage (16-18-days old) GR and non-GR soybean were examined in the greenhouse. In GR soybean, a single application of glyphosate-isopropylammonium (1.12-13.44 kg/ha) with 0.5% Tween 20 did not significantly reduce the chlorophyll content of the second trifoliolate leaf at 7 days after treatment (DAT) or the shoot dry weight at 14 DAT compared with Tween 20 alone. A single application of AMPA (0.12-8.0 kg/ha) with 0.5% Tween 20 reduced the chlorophyll content of the second trifoliolate leaf by 0-52% at 4 DAT and reduced shoot fresh weight by 0-42% at 14 DAT in both GR and non-GR soybeans compared with Tween 20 alone. AMPA at 0.12 and 0.50 kg/ha produced injury in GR and non-GR soybean, respectively, similar to that caused by glyphosate-isopropylammonium at 13.44 kg/ha in GR soybean. AMPA levels found in AMPA-treated soybean of both types and in glyphosate-treated GR soybean correlated similarly with phytotoxicity. These results suggest that soybean injury to GR soybean from glyphosate is due to AMPA formed from glyphosate degradation.  相似文献   

3.
Experiments were conducted to determine (1) dose response of glyphosate-resistant (GR) and -susceptible (non-GR) soybean [Glycine max (L.) Merr.] and canola (Brassica napus L.) to glyphosate, (2) if differential metabolism of glyphosate to aminomethyl phosphonic acid (AMPA) is the underlying mechanism for differential resistance to glyphosate among GR soybean varieties, and (3) the extent of metabolism of glyphosate to AMPA in GR canola and to correlate metabolism to injury from AMPA. GR50 (glyphosate dose required to cause a 50% reduction in plant dry weight) values for GR (Asgrow 4603RR) and non-GR (HBKC 5025) soybean were 22.8 kg ae ha-1 and 0.47 kg ha-1, respectively, with GR soybean exhibiting a 49-fold level of resistance to glyphosate as compared to non-GR soybean. Differential reduction in chlorophyll by glyphosate was observed between GR soybean varieties, but there were no differences in shoot fresh weight reduction. No significant differences were found between GR varieties in metabolism of glyphosate to AMPA, and in shikimate levels. These results indicate that GR soybean varieties were able to outgrow the initial injury from glyphosate, which was previously caused at least in part by AMPA. GR50 values for GR (Hyola 514RR) and non-GR (Hyola 440) canola were 14.1 and 0.30 kg ha-1, respectively, with GR canola exhibiting a 47-fold level of resistance to glyphosate when compared to non-GR canola. Glyphosate did not cause reduction in chlorophyll content and shoot fresh weight in GR canola, unlike GR soybean. Less glyphosate (per unit leaf weight) was recovered in glyphosate-treated GR canola as compared to glyphosate-treated GR soybean. External application of AMPA caused similar injury in both GR and non-GR canola. The presence of a bacterial glyphosate oxidoreductase gene in GR canola contributes to breakdown of glyphosate to AMPA. However, the AMPA from glyphosate breakdown could have been metabolized to nonphytotoxic metabolites before causing injury to GR canola. Injury in GR and non-GR canola from exogenous application of AMPA was similar.  相似文献   

4.
Previous greenhouse studies have demonstrated that photosynthesis in some cultivars of first‐ (GR1) and second‐generation (GR2) glyphosate‐resistant soybean was reduced by glyphosate. The reduction in photosynthesis that resulted from glyphosate might affect nutrient uptake and lead to lower plant biomass production and ultimately reduced grain yield. Therefore, a field study was conducted to determine if glyphosate‐induced damage to soybean (Glycine max L. Merr. cv. Asgrow AG3539) plants observed under controlled greenhouse conditions might occur in the field environment. The present study evaluated photosynthetic rate, nutrient accumulation, nodulation, and biomass production of GR2 soybean receiving different rates of glyphosate (0, 800, 1200, 2400 g a.e. ha–1) applied at V2, V4, and V6 growth stages. In general, plant damage observed in the field study was similar to that in previous greenhouse studies. Increasing glyphosate rates and applications at later growth stages decreased nutrient accumulation, nodulation, leaf area, and shoot biomass production. Thus, to reduce potential undesirable effects of glyphosate on plant growth, application of the lowest glyphosate rate for weed‐control efficacy at early growth stages (V2 to V4) is suggested as an advantageous practice within current weed control in GR soybean for optimal crop productivity.  相似文献   

5.
Previous research has demonstrated that glyphosate can affect nitrogen fixation or nitrogen assimilation in soybean. This 2-year field study investigated the effects of glyphosate application of 1.12 and 3.36 kg of ae ha(-1) on nitrogen metabolism and seed composition in glyphosate-resistant (GR) soybean. There was no effect of glyphosate application on nitrogen fixation as measured by acetylene reduction assay, soybean yield, or seed nitrogen content. However, there were significant effects of glyphosate application on nitrogen assimilation, as measured by in vivo nitrate reductase activity (NRA) in leaves, roots, and nodules, especially at high rate. Transiently lower leaf nitrogen or (15)N natural abundance in high glyphosate application soybean supports the inhibition of NRA. With the higher glyphosate application level protein was significantly higher (10.3%) in treated soybean compared to untreated soybean. Inversely, total oil and linolenic acid were lowest at the high glyphosate application rate, but oleic acid was greatest (22%) in treated soybean. These results suggest that nitrate assimilation in GR soybean was more affected than nitrogen fixation by glyphosate application and that glyphosate application may alter nitrogen and carbon metabolism.  相似文献   

6.
Measurement of shikimic acid accumulation in response to glyphosate inhibition of 5-enolpyruvylshikimate-3-phosphate synthase is a rapid and accurate assay to quantify glyphosate-induced damage in sensitive plants. Two methods of assaying shikimic acid, a spectrophotometric and a high-performance liquid chromatography (HPLC) method, were compared for their accuracy of recovering known amounts of shikimic acid spiked into plant samples. The HPLC method recovered essentially 100% of shikimic acid as compared with only 73% using the spectrophotometric method. Relative sensitivity to glyphosate was measured in glyphosate-resistant (GR) and non-GR cotton leaves, fruiting branches, and squares (floral buds) by assaying shikimic acid. Accumulation of shikimic acid was not observed in any tissue, either GR or non-GR, at rates of 5 mM glyphosate or less applied to leaves. All tissues of non-GR plants accumulated shikimic acid in response to glyphosate treatment; however, only fruiting branches and squares of GR plants accumulated a slight amount of shikimic acid. In non-GR cotton, fruiting branches and squares accumulated 18 and 11 times, respectively, more shikimic acid per micromolar of translocated glyphosate than leaf tissue, suggesting increased sensitivity to glyphosate of reproductive tissue over vegetative tissue. GR cotton leaves treated with 80 mM of glyphosate accumulated 57 times less shikimic acid per micromolar of translocated glyphosate than non-GR cotton but only 12.4- and 4-fold less in fruiting branches and squares, respectively. The increased sensitivity of reproductive structures to glyphosate inhibition may be due to a higher demand for shikimate pathway products and may provide an explanation for reports of fruit abortion from glyphosate-treated GR cotton.  相似文献   

7.
With the advent of glyphosate [N-(phosphonomethyl)glycine] tolerant crops, soils have now been receiving repeated applications of the herbicide for over 10 years in the Midwestern USA. There is evidence that long-term use of glyphosate can cause micronutrient deficiency but little is known about plant potassium (K) uptake interactions with glyphosate. The repeated use of glyphosate may create a selection pressure in soil microbial communities that could affect soil K dynamics and ultimately K availability for crops. Therefore, the objectives of this study were to characterize the effect of foliar glyphosate applied to GR (glyphosate resistant) soybeans on: (1) rhizosphere microbial community profiles using ester linked fatty acid methyl ester (EL-FAME) biomarkers, (2) exchangeable, non-exchangeable, and microbial K in the rhizosphere soil, and (3) concentrations of soybean leaf K. A greenhouse study was conducted in a 2 × 2 × 3 factorial design with two soil treatments (with or without long-term field applications of glyphosate), two plant treatments (presence and absence of soybean plants), and three rates of glyphosate treatments (0×, 1× at 0.87, and 2× at 1.74 kg ae ha?1, the recommended field rate). After each glyphosate application, rhizosphere soils were sampled and analyzed for microbial community structure using ester linked fatty acid methyl ester biomarkers (EL-FAME), and exchangeable, plant tissue and microbial biomass K. Glyphosate application caused a significant decrease in the total microbial biomass in soybean rhizosphere soil that had no previous exposure to glyphosate, at 7 days after glyphosate application. However, no significant changes were observed in the overall microbial community structure. In conclusion, the glyphosate application lowered the total microbial biomass in the GR soybean rhizosphere soil that had no previous exposure to glyphosate, at 7 days after glyphosate application; caused no changes in the microbial community structure; and did not reduce the plant available K (soil exchangeable or plant tissue K).  相似文献   

8.
Abstract

The widespread use of glyphosate‐resistant (GR) cropping systems may impact rhizosphere microbial associations and crop productivity. It was previously reported that glyphosate accumulation in the rhizosphere may stimulate colonization of soybean [Glycine max (L.) Merr.] roots by soilborne Fusarium. Field studies often reveal inconsistent root colonization by Fusarium, especially during growing seasons characterized by contrasting rainfall patterns. Therefore, this study was conducted to determine the impact of different soil moisture contents on root colonization of glyphosate‐treated soybean by Fusarium species. Glyphosate (0.84 kg ae ha?1) was applied to greenhouse‐grown glyphosate‐resistant (GR) soybean at the two to three trifoliate-leaf (V2–V3) growth stage growing in a Mexico silt loam at 27%, 13%, and 10% soil moisture contents. Soil and plant samples were sampled periodically after herbicide application and selectively cultured for Fusarium. Highest Fusarium colonization was associated with the glyphosate treatment, with maximum levels occurring at the highest soil moisture level. Thus, glyphosate interactions with root colonization by Fusarium in glyphosate‐resistant soybean are greatly influenced by soil moisture content.  相似文献   

9.
High levels of aminomethylphosphonic acid (AMPA), the main glyphosate metabolite, have been found in glyphosate-treated, glyphosate-resistant (GR) soybean, apparently due to plant glyphosate oxidoreductase (GOX)-like activity. AMPA is mildly phytotoxic, and under some conditions the AMPA accumulating in GR soybean correlates with glyphosate-caused phytotoxicity. A bacterial GOX is used in GR canola, and an altered bacterial glyphosate N-acetyltransferase is planned for a new generation of GR crops. In some weed species, glyphosate degradation could contribute to natural resistance. Neither an isolated plant GOX enzyme nor a gene for it has yet been reported in plants. Gene mutation or amplification of plant genes for GOX-like enzyme activity or horizontal transfer of microbial genes from glyphosate-degrading enzymes could produce GR weeds. Yet, there is no evidence that metabolic degradation plays a significant role in evolved resistance to glyphosate. This is unexpected, considering the extreme selection pressure for evolution of glyphosate resistance in weeds and the difficulty in plants of evolving glyphosate resistance via other mechanisms.  相似文献   

10.
There is evidence that glyphosate application in soybean tolerant to herbicides could interfere in the manganese (Mn) nutrition of the crop, but there is no information on this effect in cotton plants. This study aimed at assessing manganese accumulation and distribution in cotton as affected by glyphosate application. The experiment was conducted in nutrient solution with four Mn concentrations and two cotton cultivars: conventional NuOpal and NuOpal tolerant to glyphosate (RR). Glyphosate was applied or not to the tolerant cultivar. The inclusion of the glyphosate resistance gene in cotton and herbicide, application increased shikimic acid (ShA) concentration in the plants. Glyphosate application decreased cotton leaf area and the dry matter production of the plant structures. The adverse effects of glyphosate were not overcome with higher Mn rates in the solution.  相似文献   

11.
The compositional analyses and safety assessment of glyphosate-tolerant soybeans (GTS) were previously described. These analyses were extensive and included addressing the potential effects on seed composition from the genetic modification. Detailed compositional analyses established that GTS, which had not been treated with glyphosate, were comparable to the parental soybean line and to other conventional soybeans. In this study, two GTS lines, 40-3-2 and 61-67-1, were treated with commercial levels of glyphosate, the active ingredient in Roundup herbicide. The composition of the seed from soybeans sprayed with glyphosate was compared to that of a nonsprayed parental control cultivar, A5403. The nutrients measured in the seed included protein, oil, ash, fiber, carbohydrates, and amino acids. The concentration of isoflavones (also referred to as phytoestrogens) was also measured as these compounds are derived from the same biochemical pathway that was engineered for glyphosate tolerance. The analytical results from these studies demonstrate that the GTS soybeans treated with glyphosate were comparable to the parental soybean cultivar, A5403, and other conventional soybean varieties.  相似文献   

12.
The parasitic plant broomrape is entirely dependent on its host for reduced carbon and nitrogen and is also susceptible to inhibition by glyphosate that is translocated to the parasite through a host. Studies were conducted to examine the effect of broomrape parasitism on amino acid concentrations of two hosts: common vetch that is tolerant of low levels of glyphosate and oilseed rape that has been genetically engineered for glyphosate resistance. The influence of glyphosate on the amino acid content of broomrape and the two hosts was also examined. Amino acid concentrations in leaves and roots of parasitized common vetch plants were generally similar to those of the corresponding tissues of nonparasitized plants. Amino acid concentrations in broomrape were lower than those of the parasitized common vetch root. For common vetch, glyphosate applied at rates that selectively inhibited broomrape growth did not alter individual amino acid concentrations in the leaves, but generally increased amino acid levels at 0.18 kg ha-1. Glyphosate application also increased the amino acid concentrations, with the exception of arginine, of broomrape growing on common vetch and did not generally influence concentrations in leaves or roots of common vetch. In oilseed rape, parasitization by broomrape generally led to higher amino acid concentrations in leaves but lower concentrations in roots of parasitized plants. Broomrape had higher amino acid concentrations than roots of the parasitized oilseed rape. Glyphosate applied at 0.25 and 0.5 kg ha-1 generally increased the amino acid concentrations in oilseed rape leaves, but the 0.75 kg ha-1 application caused the amino acid concentrations to decrease compared to those of untreated plants. In oilseed rape root the general trend was an increase in the concentration of amino acids at the two highest rates of glyphosate. Individual amino acid concentrations in broomrape attachments growing on oilseed rape were generally increased following glyphosate application of 0.25 kg ha-1. These results indicate that low rates of glyphosate alter amino acid profiles in both host and broomrape and raise questions about the regulation of amino acid metabolism in the parasite.  相似文献   

13.
为筛选耐草甘膦野生大豆种质并了解其耐性机制,本试验对采集于冀东地区的862份野生大豆进行了草甘膦的耐性鉴定。在草甘膦处理后,测定了高耐和敏感材料的莽草酸、丙二醛和叶绿素含量,过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性,以及草甘膦相关基因EPSPS表达量。结果显示,喷施草甘膦后,862份野生大豆材料中,药害等级在4级以上的材料占82.84%,3级占9.51%,2级占4.87%,1级占2.78%。筛选到高耐草甘膦的野生大豆材料Yong-33,其在1.125 kg a.i·hm-2 草甘膦处理后植株存活率达到96.67%。经草甘膦处理后,与对照相比,高耐材料的叶绿素、丙二醛和莽草酸含量在检测的各时间点均无显著差异,敏感材料叶绿素含量显著降低,丙二醛和莽草酸含量显著升高;高耐材料POD、CAT和SOD活性以及EPSPS基因表达量均显著升高,而敏感材料酶活性及EPSPS基因表达量无显著差异。以上结果表明,野生大豆中存在高耐草甘膦的种质资源,在草甘膦处理后其植株内活性氧清除酶系活性升高,EPSPE基因上调表达,推测这是野生大豆对草甘膦耐性较好的原因。本研究筛选到的耐草甘膦野生大豆材料可为培育耐草甘膦栽培大豆新品种提供种质资源。  相似文献   

14.
Glyphosate and phosphorus (P) fertilizer may alter arbuscular mycorrhizal (AM) fungal infection rates of glyphosate-tolerant cotton, maize, and soybean in low-P soil. Microbial biomass, water soluble P, Mehlich-3 P, and acid and alkaline phosphatase activities were not significantly impacted by glyphosate or P in the greenhouse. Phosphorus fertilization decreased mycorrhizal infection rates in cotton and maize and increased shoot biomass and shoot P in soybean in 2005, and decreased mycorrhizal infection in soybean and increased shoot biomass in cotton and maize and shoot P in all three crops in 2006. In pasteurized soil, glyphosate decreased percent mycorrhizal infection in maize, increased infection in cotton, and did not significantly affect infection in soybean. When soil was not pasteurized, glyphosate did not significantly alter mycorrhizal infection in any crop. The potential for glyphosate to alter AM fungal infection in glyphosate-tolerant plants may depend on whether soil microbial communities are compromised by other factors.  相似文献   

15.
Aminomethylphosphonic acid (AMPA) is the most frequently detected metabolite of glyphosate in plants. The objective of this study was to determine if there is any correlation of metabolism of glyphosate to AMPA in different plant species and their natural level of resistance to glyphosate. Greenhouse studies were conducted to determine the glyphosate I 50 values (rate required to cause a 50% reduction in plant growth) and to quantify AMPA and shikimate concentrations in selected leguminous and nonleguminous species treated with glyphosate at respective I 50 rates. Coffee senna [ Cassia occidentalis (L.) Link] was the most sensitive ( I 50 = 75 g/ha) and hemp sesbania [ Sesbania herbacea (P.Mill.) McVaugh] was the most resistant ( I 50 = 456 g/ha) to glyphosate. Hemp sesbania was 6-fold and Illinois bundleflower [ Desmanthus illinoensis (Michx.) MacM. ex B.L.Robins. & Fern.] was 4-fold more resistant to glyphosate than coffee senna. Glyphosate was present in all plant species, and its concentration ranged from 0.308 to 38.7 microg/g of tissue. AMPA was present in all leguminous species studied except hemp sesbania. AMPA concentration ranged from 0.119 to 4.77 microg/g of tissue. Shikimate was present in all plant species treated with glyphosate, and levels ranged from 0.053 to 16.5 mg/g of tissue. Non-glyphosate-resistant (non-GR) soybean accumulated much higher shikimate than glyphosate-resistant (GR) soybean. Although some leguminous species were found to be more resistant to glyphosate than others, and there was considerable variation between species in the glyphosate to AMPA levels found, metabolism of glyphosate to AMPA did not appear to be a common factor in explaining natural resistance levels.  相似文献   

16.
为探明干旱胁迫及复水条件下不同剂量草甘膦对抗草甘膦大豆(RR1)幼苗叶片渗透调节物质、莽草酸(shikimic acid, SA)含量及根系活力的影响,采用盆栽试验,在大豆的第3复叶期进行水分胁迫5d和除草剂草甘膦处理,研究RR1幼苗叶片可溶性蛋白(soluble protein, SP)、可溶性糖(soluble sugar, SS)、游离脯氨酸(free praline, FP)、莽草酸(shikimic acid, SA)含量和根系活力(RA)的变化。结果表明,干旱胁迫前期RR1叶片的SP含量随草甘膦剂量的增加呈先升高后降低趋势,0.46kg/hm2叶片SP的含量最高,胁迫后期SP含量随草甘膦剂量的增加而降低;SS、FP和SA含量随草甘膦剂量的增加和胁迫时间的延长而增加,RA随草甘膦剂量的增加和胁迫时间的延长而降低。复水12d后,不同剂量草甘膦处理的各指标均有所恢复。干旱条件下,经草甘膦处理的RR1叶片的SP含量和RA低于草甘膦在正常水分条件下的处理,而SS、FP和SA含量相反。相关性分析表明,FP和SA含量与草甘膦剂量的相关关系最明显;而SS和SA含量与干旱胁迫时间的相关关系最明显。说明正常水分条件下,草甘膦对RR1幼苗造成的伤害经过一段时间后有所缓解;干旱胁迫加剧了草甘膦对RR1幼苗叶片渗透调节物质、莽草酸含量和根系活力的影响。抗草甘膦大豆主要通过积累FP、SS和SA对草甘膦和干旱胁迫做出响应。  相似文献   

17.
Nontarget injury from glyphosate drift is a concern among growers using non-glyphosate-resistant (non-GR) cultivars. The effects of glyphosate drift on nitrate assimilation and nitrogen fixation potential, nodule mass, and yield of non-GR soybean were assessed in a field trial at Stoneville, MS. A non-GR soybean cultivar 'Delta Pine 4748S' was treated with glyphosate at 12.5% of use rate of 0.84 kg of active ingredient/ha at 3 (V2), 6 (V7), and 8 (R2, full bloom) weeks after planting (WAP) soybean to simulate glyphosate drift. Untreated soybean was used as a control. Soybeans were sampled weekly for 2 weeks after each glyphosate treatment to assess nitrate assimilation and N2 fixation potential. Nitrate assimilation was assessed using in vivo nitrate reductase assay in leaves, stems, roots, and nodules. Nitrogen fixation potential was assessed by measuring nitrogenase activity using the acetylene reduction assay (ARA). Nitrogen content of leaves, shoots, and seed and soybean yield were also determined. In the first sampling date (4 WAP), glyphosate drift caused a significant decrease in NRA in leaves (60%), stems (77%), and nodules (50%), with no decrease in roots. At later growth stages, NRA in leaves was more sensitive to glyphosate drift than stems and roots. Nitrogenase activity was reduced 36-58% by glyphosate treatment at 3 or 6 WAP. However, glyphosate treatment at 8 WAP had no effect on nitrogenase activity. Nitrogen content was affected by glyphosate application only in shoots after the first application. No yield, seed nitrogen, protein, or oil concentration differences were detected. These results suggest that nitrate assimilation and nitrogen fixation potential were significantly reduced by glyphosate drift, with the greatest sensitivity early in vegetative growth. Soybean has the ability to recover from the physiological stress caused by glyphosate drift.  相似文献   

18.
Maize was grown for 36 days in solution culture with roots either under axenic conditions or in the presence of rhizosphere organisms. In other experiments with sterile roots the plants were grown with different concentrations of potassium. At the end of the experiments sugars, organic acids and amino acids in the nutrient solutions were determined. Under axenic conditions the exudates consisted of up to 65% sugars, up to 33% organic acids and only up to 2% amino acids. The same substances were detected in non-sterile nutrient solutions. In the presence of microorganisms fructose, arabinose and the predominating glucose decreased to almost one half, while sucrose was not affected. The amounts of organic acids were not changed by microbial growth. The main amino acid, glutamic acid, was nearly doubled by the presence of microorganisms, whereas other amino acids remained unchanged. The lower O2 content of the nutrient solutions of non-sterile roots suggested microbial decomposition of monosaccharides. In another experiment with roots grown under axenic conditions and with different K treatments low K supply significantly increased the total amounts of sugars, organic acids and amino acids exuded g?1 root dry matter. As in the previous experiment glucose, fumaric and oxalacetic acid as well as glutamic and aspartic acid dominated in the respective fractions. Again sugars and organic acids represented the major quantity of exudates, while amino acids amounted to less than 2%. In an additional experiment with another cultivar, with nitrate as N source and a 5-day longer growth period, somewhat different results were obtained. In the exudates sugars were found in lower amounts, probably due to a higher growth rate. Under these conditions organic acids were the prevailing root exudates. Unlike sugars and amino acids, their total quantity was not affected by K nutrition, but the proportion of malic acid increased with increasing K supply, while oxalacetic acid dominated at low K nutrition. Similarly the total amount of organic acids within the root was independent of K nutrition. However malic acid content increased with increasing K application, while the likewise dominating citric and oxalacetic acid decreased.  相似文献   

19.
Abstract

Foliar fertilization with micronutrients and amino acids (AAs) has been used to increase the grain yield and quality of different crops. The aim of the present study was to evaluate the effects of Zn and AAs foliar application on physiological parameters, nutritional status, yield components and grain yield of wheat-soybean intercropping under a no-till management. We used a randomized block experimental design consisting of eight treatments and four replicates. The treatments were five Zn rates (0, 1, 2, 4 and 8?kg ha?1) and 2?L ha?1 of AAs and three additional treatments: a control (without the Zn or AA application), 2?kg ha?1 Zn and 2?kg ha?1 Zn + 1?L AA. The treatments were applied by spraying during the final elongation stage and at the beginning of pre-earing for the wheat and in growth stage V6 for the soybean for two crop years in a Typic Oxisol (860?g kg?1 clay). Zinc foliar fertilization increased the wheat grain Zn concentrations. The Zn rates and AA foliar fertilization in soil with did not affect the physiological parameters, nutrient status or yield components. The AA application at the different concentrations tested changed the soybean grain yield and the leaf N concentration. The results suggest that Zn and amino acids application increases the grains Zn concentration in the wheat, being an important strategy to agronomic biofortification.  相似文献   

20.
Abstract

Soybean [Glycine max (L.) Merr.] yield losses may be attributable to early-season nutrient competition with weeds; however, research investigating macro- and micronutrient accumulation of weeds in soybean is scarce. Field experiments were conducted across eight site-years in Illinois, USA to determine which soybean nutrients are most susceptible to weed competition. Weeds were controlled by applying glyphosate at 10-, 20-, 30-, or 45-cm weed heights during which accumulation of 11 nutrients were measured in soybean and broadleaf and grass weeds. For both weed groups, K and Fe were the macro- and micronutrient, respectively, with the greatest rate of accumulation. Variations in nutrient uptake between broadleaf and grass weeds were largely explained by differences in weed density, except for Ca and B, which were greater in broadleaf weeds regardless of density. Canonical discriminant analysis (CDA) identified soybean accumulation of N, P, K, Fe, and Cu as the nutrients most affected by weed competition, with P, K, and Fe uptake being particularly susceptible during droughty conditions. The weed height causing a 10% reduction in uptake was 11, 12, 12, 7, and 10?cm for N, P, K, Fe, and Cu, respectively. Soybean grain yield, seed weight, pods plant?1, and seed oil content were identified through CDA as the yield parameters most affected by weed competition. Results indicate weeds should be removed before reaching 18?cm (V2 to V3 soybean) to avoid a 5% loss in grain yield. Early-season weed control preserves yield potential and may improve efficiency of nutrient management programs in soybean.  相似文献   

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