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1.
Application of glyphosate herbicide in genetically modified (GM) soybean [Glycine max (L.) Merrill] in soils with low zinc (Zn) concentration may interfere in the uptake of this and other nutrients, with negative impact on productivity. Thus, an experiment was conducted in greenhouse conditions on Ustoxix Quatzipsamment soil to investigate the effects of the interaction of glyphosate with Zn for the yield, photosynthesis, soil fertility and nutritional status of soybean. The treatments consisted of two soybean varieties [BRS 133 (conventional—NGM) and its essentially derived transgenic line BRS 245RR (GM) with and without glyphosate application] and five Zn rates (0, 5, 10, 20 and 40 mg kg?1, source zinc sulfate (ZnSO4)), with four replicates. Except for the copper (Cu) and iron (Fe) concentrations, the introduction of the herbicide-resistant gene is the predominant factor reducing nutrient uptake, photosynthetic (A) rate, stomatal conductance (Gs), leaf chlorophyll and ureide concentrations. The administration of Zn rates lowered the leaf phosphorus (P) concentration, and there was significant increase in Zn concentration in the soil and in the plant. Except for the 20 mg kg?1 of Zn rate, the use of the herbicide did not affect the shoot dry weight (SDW) and seed yield, and on average, the maximum seed yield was obtained with Zn concentrations of 26.4 and 18.7 mg kg?1 extracted by Mehlich 1 and diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA), respectively.  相似文献   

2.
The use of cultivar with nutrient-use efficiency is an important strategy in the management of plant nutritional status, particularly potassium (K), because its high demand and the progressive impoverishment caused by the use of inadequate amounts cause frequent deficiency symptoms observed in soybean [Glycine max (L.) Merrill] crops. This study was conducted in greenhouse conditions in a completely randomized design with four replicates in an Typic Quartzipsamment soil aimed to assess the effect of applying two rates of K (50 and 200 mg kg?1) on growth, shoot dry weight yield (SDWY) and seed yield (SY), nutritional status, yield components, and efficiency of K use in eleven cultivars of different characteristics and growth habits. The SDWY, SY, number of seeds per pod, number of pods, and estimated 100-seed weight showed significant interaction between cultivar and the K rates, with greater values at the rate 200 mg K kg?1. Similarly, the concentration of nitrogen (N), phosphorus (P), K, calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) in leaves and grains varied according to the K rates and in the cultivar. The most K-use efficient cultivars were BMX Magna RR, BRS 232, BRS 284, BRS 294RR, NA 5909RR, and Vmax RR, whereas FTS Campo Mourão RR was inefficient. Regarding response to fertilization, the cultivars Vmax RR, BMX Magna RR, NA 5909RR, BRS 284, and BRS 294RR were found to be efficient and responsive, whereas the cultivar FTS Campo Mourão RR, BRS 232, BMX Potência RR, BRS 295RR, TMG 1066RR, and TMG 1067RR are inefficient and responsive to K application in the soil.  相似文献   

3.
Expansion of soybean [Glycine max (L.) Merrill] cultivated in Brazil to regions with low fertility soils gave rise to studies on the possibility of obtaining highly productive cultivars with high nutrient use efficiency. An experiment in greenhouse conditions was conducted to assess phosphorus (P) use efficiency (PUE) by 13 soybean genotypes. The genotypes were grown in an Ustoxix Quartzipsamment with two P rates [0 (no P application) and 150 mg P kg?1], whose source was monoammonium phosphate (MAP, P2O5 44%). Shoot dry weight (SDW), grain yield (GY), grain harvest index (GHI), relative yield (RY), and physiological components (photosynthetic rate, stomatal conductance, respiratory rate, and internal CO2 concentration) were influenced by soybean genotypes and P rates. Genotypes BMX Apolo RR, BRS 360RR, BRS 378RR, CD 219RR, DM 2302RR, TMG 7161RR, and Vtop RR were classified as non-efficient and non-responsive to P application, while BMX Potência RR, Vmax RR, FPS Solar RR, NA 5909RR, TMG 1066RR, and M 6210 IPRO were classified as efficient and responsive. Phosphorus application increased the values of physiological components, which was not observed for N, K, Ca, Mg, and S concentration in the leaves and grains. Soybean genotypes selection for increased P efficiency could help growers overcome the problem of soybean cultivation on new areas or degraded pastures.  相似文献   

4.
The magnesium (Mg) use efficiency in the selection of common bean (Phaseolus vulgaris L.) varieties may contribute to increased nutritional status and grain yield. Therefore, the present study aimed to assess common bean varieties following the application of Mg regarding productivity (yield), soil fertility, physiological components, and nutritional status. The experiment was conducted in a completely randomized design in a 5 × 2 factorial scheme with three replicates. Five common bean varieties [BRS Estilo, IPR Tangará, IPR Campos Gerais (CG), IAPAR 81, and BRS Ametista] supplemented with two Mg concentrations [low (0 mg kg?1) and high (100 mg kg?1)] using magnesium chloride (MgCl2) as a source in an Ustoxix Quatzipsamment were assessed. The yield of shoot dry weight (SDW) and grains varied significantly between varieties and Mg rates. The high Mg concentration has negatively affected the yield of SDW and grains of variety IPR Tangará, and the opposite was observed for the other varieties. The physiological components associated with photosynthesis are directly related to the yield of SDW and grains. The concentrations of phosphorus (P), calcium (Ca), sulfur (S), and boron (B) in leaves and of S, B, iron (Fe), and manganese (Mn) in grains differed among the varieties and interactions of rates and varieties for B, indicating the presence of genetic factors in nutrient uptake.  相似文献   

5.
The selection of varieties or species of plants with higher nutrient uptake efficiency and nutrient concentration for biofortification of food crops is a key tool to reduce malnutrition. Soybean (Glycine max L. Merr) is one of the most important food crops, because it is consumed directly or indirectly, in the form of seeds, processed (milk and/or derivatives), or used as a protein component of animal feed worldwide. In order to select plants with higher nutrients concentration in seeds, 24 soybean varieties for tropical and subtropical conditions and different general features were assessed. There was great variability in photosynthesis rate, chlorophyll content, seed yield (SY), and concentration and uptake of nutrients by seeds between the varieties. Not genetically modified (NGM) crops showed higher nitrogen (N), cooper (Cu), and manganese (Mn) concentration and higher N, potassium (K), Cu, iron (Fe), Mn, and zinc (Zn) uptake, while for genetically modified (GM) crops only calcium (Ca) concentrations were higher. Varieties BRS 284 and BMX Magna RR showed the highest nutrients concentrations in the group with the highest nutrient efficiency. The genetic variability observed among the varieties regarding uptake and translocation of nutrients into seeds allows selecting more promising materials to be used in the biofortification of nutrients in soybean seeds.  相似文献   

6.
Soybean [Glycine max (L.) Merril] is the leading food crop worldwide, and selection of soybean genotypes for different levels of soil acidity may raise crop yield without the need to increase in planted area. An experiment in greenhouse conditions was conducted to determine the effects of two lime rates on soil chemical properties, grain yield (GY), yield components, nutritional status and physiological components of 15 soybean genotypes adapted to tropical and subtropical conditions. Genotypes BMX Apolo RR, BMX Potência RR, BRS 295RR, BRS 359RR, FPS Solar IPRO and TMG 716 IRR were the least responsive to soil acidity reduction, and BMX Turbo RR and BRS 360RR were the most responsive. Number of pods per pot, shoot dry weight yield, GY, photosynthesis, stomatal conductance, transpiration and chlorophyll increased significantly with increase in lime rate. Cultivar FPS Solar IPRO showed the highest foliar P, K, Ca and Mg concentrations in soybean, which was not observed in the grain, indicating the presence of genetic factors and the dilution effect on nutrient uptake.  相似文献   

7.
The appropriate supply of magnesium (Mg) to the common bean (Phaseolus vulgaris L.) according to the requirements of each variety increases the productivity and nutritional value of grains. However, there are few studies on soil's ability to provide the adequate amount of the nutrient and on the reaction of plants with different Mg concentrations. The present study analyzed the response of the common bean plant to soil fertility, grain yield (GY), shoot dry weight (SDW) yield, nutritional status and the response of physiological components of the plant to the concentrations of Mg applied to the tropical soil. Thus, an experiment was conducted in a completely randomized design, in 5 × 4 factorial arrangement, with three replicates. The varieties BRS Estilo, IAPAR 81, BRS Ametista, IPR Campos Gerais (CG) and IPR Tangará were cultivated in an Ustoxix Quatzipsamment with five rates of Mg [0, 50, 100, and 200 mg kg?1, source magnesium chloride (MgCl2)]. The common bean varieties and the Mg rates significantly affected the soil chemical properties. Photosynthetic rate, stomatal conductance, transpiration rate, intercellular concentration of carbon dioxide (CO2), and total soluble sugars significantly correlated with common bean GY and SDW yield. The nutrient content in leaves and grains showed difference responses among the varieties. IAPAR 81 showed the highest rate of mobilization of nitrogen, phosphorus, magnesium, sulfur, boron, copper and zinc (N, P, Mg, S, B, Cu, and Zn) for grains, being an important factor in studies of crop biofortification.  相似文献   

8.
Abstract

Using the results of seventy‐one soybean (Glycine max) variety performance trials, the existence of a yield drag (YD) of herbicide‐resistant varieties when compared to conventional varieties is verified. The trials were conducted from 1996 to 2000 at five locations, on 569 varieties covering three maturity groups in irrigated and dryland conditions using conventional tillage. Trend analysis of YD suggests that it (i) is magnified by irrigation; (ii) has declined to negligible levels; (iii) is not significantly different across maturity group; and (iv) exhibits some locational differences. An analysis of six herbicide programs revealed that glyphosate programs are generally more expensive than reduced‐rate conventional programs but are comparable to or cheaper than full‐rate conventional herbicide regimes. It is further conjectured that seed/technology and herbicide cost differences across seed/herbicide systems will adjust to competitive conditions in the long run.  相似文献   

9.
Most soybeans grown in North America are genetically modified (GM) to tolerate applications of the broad-spectrum herbicide glyphosate; as a result, glyphosate is now extensively used in soybean cropping systems. Soybean roots form both arbuscular mycorrhizal (AM) and rhizobial symbioses. In addition to individually improving host plant fitness, these symbioses also interact to influence the functioning of each symbiosis, thereby establishing a tripartite symbiosis. The objectives of this study were to (1) estimate the effects of glyphosate on the establishment and functioning of AM and rhizobial symbioses with GM soybean, and (2) to estimate the interdependence of the symbioses in determining the response of each symbiosis to glyphosate. These objectives were addressed in two experiments; the first investigated the importance of the timing of glyphosate application in determining the responses of the symbionts and the second varied the rate of glyphosate application. Glyphosate applied at recommended field rates had no effect on Glomus intraradices or Bradyrhizobium japonicum colonization of soybean roots, or on soybean foliar tissue [P]. N2-fixation was greater for glyphosate-treated soybean plants than for untreated-plants in both experiments, but only when glyphosate was applied at the first trifoliate soybean growth stage. These data deviate from previous studies estimating the effect of glyphosate on the rhizobial symbiosis, some of which observed negative effects on rhizobial colonization and/or N2-fixation. We did observe evidence of the response of one symbiont (stimulation of N2-fixation following glyphosate) being dependent on co-inoculation with the other; however, this interactive response appeared to be contextually dependent as it was not consistent between experiments. Future research needs to consider the role of environmental factors and other biota when evaluating rhizobial responses to herbicide applications.  相似文献   

10.
Sulfur (S) is an essential nutrient in crop plants and one of the components of amino acids (AAs) and proteins. Studies about sulfur efficiency on soybean cultivars [Glycine max (L) Merril] adapted to the tropical and subtropical conditions are still incipient. In Brazil, one experiment under greenhouse conditions evaluated the S-efficiency from eight soybean cultivars. The plants cultivated in a Typic Quartzipsamment received two S rates (0 and 80 mg kg?1). The grain yield (GY), shoot dry weight (SDW), and the relative yield (RY) had influence from the S rates. The cultivars BRS 295RR and BRS 360RR were the most efficient in using the S application. The number of pods per plant (NPP), photosynthetic rate (A), nitrate reductase (N-NO2?), and chlorophyll significantly increased with de 80 mg kg?1 of S. By contrast, the internal concentration of carbon dioxide (CO2) (Ci) was reduced. Similarly, there were increases in the concentration of nitrogen (N), phosphorus (P), magnesium (Mg), and N:S ratio in the leaves and grain, but the K increased only in the leaves. Comparing the cultivars, only the N concentration in the leaves and the Mg in the grain had non-significant differences.  相似文献   

11.
Studies on the effect of groundcover treatments on perennial tree crops have been common in recent decades. However, few have included leaf analysis as an aid to understand the effects of groundcover treatments on tree crop growth and yield, in particular in rainfed olive orchards. Field experiments took place in northeast Portugal, over the course of eight consecutive years, in two commercial orchards selected on the basis of their contrasting situation regarding the floor-management system before the trial started. An orchard located in Bragança, currently managed as a sheep-walk, received the following treatments: sheep-walk (SW), where the natural vegetation was managed with a flock of sheep; mechanical cultivation (MC), which consisted of two tillage trips per year in the spring; and glyphosate (Gly), where the herbicide was applied once during the first fortnight of April. Another orchard near Mirandela, currently managed by tillage, received the following treatments: mechanical cultivation (MC); glyphosate (Gly); and residual herbicide (RH), where an herbicide with a residual component was applied late in the winter. The trees that underwent Gly treatments produced the greatest tree crop growth and olive yield. The worst results were achieved with the SW and MC treatments in the Bragança and Mirandela experiments, respectively. Leaf nitrogen (N) and boron (B) concentrations were significantly higher and lower, respectively, in the treatments that caused the higher and lower olive yields in both experiments. In the Mirandela orchard, where the leaf potassium (K) concentrations were close to the lower limit of the adequate range, the leaf K levels followed the pattern registered for N and B. The results showed a strong link between tree crop nutritional status and tree crop growth and olive yield. The groundcover treatments that facilitate nutrient absorption by olive trees yielded more crops.  相似文献   

12.
In agriculture there is a tendency to reduce spacing between plant rows, both for perennial and annual plants. Yield gains have been associated with the use of this technique. However, in the case of perennial plants, this technique was found to reduce productivity in older orchards because of the greater competition between plants caused by the increased volume of the crown and root system, resulting in lower photosynthetic efficiency, increased infestation with fungal diseases, and greater competition in nutrient uptake. In addition to yield, efficient management should consider soil fertility, nutritional status, and the growth of the guarana variety. The present study aimed to assess the effects of spacing and plant density on grain yield, soil fertility, and nutritional status of two guarana varieties (BRS Amazonas and BRS Maués). The plant density studied were 625 (4 m × 4 m), 833 (4 m × 3 m), 1,111 (3 m × 3 m), 1,666 (3 m × 2 m), 2,500 (2 m × 2 m), and 5,000 (2 m × 1 m) plants per hectare distributed in randomized block design with three replicates. The high plant density has significantly increased grain yield in the guarana varieties, with changes in launch number, trunk diameter, and crown diameter. Regarding macronutrients, in the average of the varieties, the mean foliar concentration had the following sequence: nitrogen (N) > potassium (K) > calcium (Ca) > phosphorus (P) > sulfur (S) > magnesium (Mg), whereas for micronutrients it was manganese (Mn) > iron (Fe) > boron (B) > zinc (Zn) > copper (Cu). The differences in the foliar concentrations of the varieties and in soil fertility are important tools for the selection of materials with better capacity of uptake and/or translocation of nutrients, resulting in greater grain yield.  相似文献   

13.
Zinc (Zn) deficiency is common among crops grown in the tropics in acid and weathered soils. In response, the use of amino-acids (AAs) to increase the uptake of this nutrient has been increasing dramatically in recent years. Nevertheless, there is a scarcity of results reported on the effect of applying AAs and adequate quantities of Zn on alfalfa grown under tropical edaphoclimatic conditions. Therefore, a greenhouse experiment was conducted with a completely randomized block in a factorial scheme (4×2) of four Zn rates of 0, 4, 8, and 16 mg kg?1) with and without spraying of AAs during the sprouting phase, to study the effects on the shoot dry weight (SDW) yield, nutritional state, physiological parameters, and soil fertility. The harvests were repeated over time (three cuts). The SDW yield was significantly influenced up to a rate of 4.0 mg kg?1 of Zn, after which it stabilized. Independent of the Zn rate, the application of AAs did not influence the SDW yield. Based on the averages for the three cuts, only the Zn rates altered the photosynthesis and chlorophyll content, with no effect of the AAs. The concentrations of Zn in the soil extracted by the Mehlich 1 and diethylenetraminepenta acetic acid (DTPA)- triethanolamine (TEA) methods were strongly and significantly correlated (r = 0.99, P ≤ 0.05) with the Zn rates and the Zn concentrations in the plant tissue. The agronomic, physiological, and zinc use efficiencies diminished with increased Zn rates, while the inverse occurred with the Zn efficiency index.  相似文献   

14.
The objective of this experimental study was to determine the effect of agronomic practices usually implemented in olive groves (addition of olive mill waste and herbicides) on soil microbial communities and to test whether drought enhanced such effects. For that purpose, mesocosms containing soil cores from olive groves were incubated for 5 months under either of the three treatments: (i) addition of olive mill waste (OMW), (ii) addition of glyphosate‐based herbicide (Gly treatment) and (iii) both treatments. Half of the mesocosms were subjected or not (controls) to drying–rewetting cycles (D/Rw) for 1 month (1 D/Rw) or 3 months (3 D/Rw). In the controls, 2 months after the Gly treatment, higher lipase activities were observed compared with no practice treatment as well as a significant change in catabolic profiles of cultivable microbial communities. Three months later, lipase activities significantly decreased under the Gly treatment. Addition of OMW together with Gly treatment counteracted the negative effect of the herbicide on lipase activities. After three D/Rw cycles, Gly treatment modified catabolic profiles and induced a decrease in functional diversity. Overall, the combination of glyphosate‐based herbicide with OMW was a conservative practice that maintained soil functioning and led to a better response to D/Rw cycles.  相似文献   

15.
Iron (Fe)-deficiency chlorosis is a common constraint when soybean (Glycine max L.) is grown on calcareous soils. Considerable differences exist among soybean genotypes for susceptibility to Fe chlorosis. In order to evaluate the effectiveness of iron-ethylenediamine di-o-hydroxyphenylacetic acid (Fe-EDDHA) for three soybean genotypes (A3237, Black hack, and Wells), field studies were conducted for the years 2001 and 2002 in a calcareous soil. Although, available Fe of the studied soils was either lower than critical level or in marginal range, application of Fe-EDDHA did not result in a significant increase in soybean yield probably, due to the antagonistic relationships between Fe and manganese (Mn). It appears that Fe soil test as the only criterion for Fe fertilizers recommendation is not appropriate and soil test for Mn is also recommended. Significant quadratic equations were obtained between chlorophyll meter readings (CMR) in growth stage 3 (GS3) with seed yield (SY) of A3237 and Black hack. However, SY of Wells showed close relationships with CMR in growth stage 4 (GS4). A tentative conclusion is that the chlorophyll meter is a reliable and non-destructive tool for the prediction of SY for the studied soybean genotypes in GS3 or GS4.

Due to the fact that use of Fe fertilizer might cause nutritional disorder, use of Fe-efficient genotypes remains as an effective and economic sound practice. However, positive responses to Fe-chelate treatments are expected for genotypes with shoot Fe: Mn ratio less than 0.4 when both nutrients are in the sufficiency range. Obviously, such a requirement limits the utilization of Fe-chelate to post-emergence fertilization.  相似文献   

16.
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   

17.
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   

18.
Over half of the 21 Mha of soybean planted in Brazil is now transgenic glyphosate-resistant (GMRR). A field experiment was carried out to investigate whether the application of glyphosate or imazethapyr to the GMRR variety reduced the input of N2 fixation (BNF). No effects on yield, total N accumulation, nodulation and BNF (δ15N) could be assigned to the genetic modification of the plant. Imazethapyr reduced soybean yield but had no significant effect on BNF. Even though yields were not affected by glyphosate, the significant reduction of nodule mass and BNF to the GMRR suggests that the use of this herbicide could lead to an increased dependence on soil N and consequently an eventual decrease of SOM reserves.  相似文献   

19.
Dry bean is an important legume for human consumption worldwide. Low soil fertility, including zinc (Zn) deficiency, is one of the main factors limiting yield of this legume in South America, including Brazil. The objective of this study was to evaluate 30 dry bean genotypes for zinc (Zn)–use efficiency. The Zn rates used were 0 mg Zn kg?1 (low) and 20 mg Zn kg?1 (high) of soil. Grain yield, straw yield, number of pods, hundred-seed weight, number of seeds per pod, maximum root length, and rood dry weight were significantly affected by Zn and genotype treatments. The Zn × genotype interactions were also significant for growth, yield, and yield components, indicating that some genotypes were highly responsive to the Zn application while others were not. Based on seed yield efficiency index (SYEI), genotypes were classified as efficient, moderately efficient, and inefficient in Zn-use efficiency. Most efficient genotypes were CNFP 10104, BRS Agreste, BRS 7762 Supreme, CNFC 10429, BRS Estilo, CNFC 10467, BRS Esplendor, and BRS Pitamaba. The most inefficient genotype was BRS Executive. Remaining genotypes were moderately efficient in Zn-use efficiency.  相似文献   

20.
Extensive and semi-extensive pastures are the basis of Brazilian livestock production. However, much of it is degraded or in degradation process, with low stocking rate per area. Even with this problem, this management type is 60% and 50% of Australia’s and the United States’ production costs, respectively. In order to research alternatives for Urochloa decumbens degraded pasture recovery in an Oxisol, Stylosanthes (Stylosanthes spp.) “Campo Grande” cultivar was introduced and phosphate fertilization was applied. The experimental design was of randomized blocks, 7 × 2 × 2 factorial design, with four replicates, involving seven systems to introduction (U. decumbens control; partial desiccation with 1.5 L ha?1 glyphosate, total desiccation with 3.0 L ha?1 glyphosate; direct planting; scarification, harrowing, and plowing + harrowing), phosphate fertilizer presence or absence, and two evaluation periods. “Campo Grande” Stylosanthes legume introduction increased shoot dry weight (SDW) yield, except in direct planting. Phosphorus fertilization increased SDW yield only in the first period, and Stylosanthes introduction in the pasture has not changed soil chemical properties. Phosphorus (P) fertilization also provided available P and exchangeable calcium (Ca2+) content in the soil increase, in addition to sum of bases and cation exchange capacity increase.  相似文献   

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