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1.
Mohsen Jalali Maryam Goharpour Somayeh Moharami 《Communications in Soil Science and Plant Analysis》2018,49(9):1022-1031
Four types of plant residues (fruit waste, potato, sunflower, and wheat) with wide ranges of carbon to nitrogen (C/N) and carbon to phosphorus (C/P) ratios were added to the soil at the rate of 20 g kg?1 (dry weight basis) and incubated for two months. In soils treated with plant residues, the P sorption ranged from 62.0% (potato) to 96.6% (wheat) and from 12.6% (fruit waste) to 50.6% (wheat) when 20 and 1500 mg P kg?1 were added to the soils, respectively. In general, incorporation of plant residues decreased maximum P sorption capacity but increased bonding energy. The maximum P sorption capacity was reduced from 586 mg kg?1to 500, 542, and 548 by wheat, fruit, and potato residues, respectively, but increased to 665 mg kg?1 by sunflower residue. At higher P addition, the highest percentage of desorbed P was observed in soils treated with wheat residue (49.9%); followed by fruit waste (46.5%), potato (43.5%), sunflower (38.8%) and control soils (37.0%). It indicated that the P content of the organic residues had an important role in the sorption and desorption of P in calcareous soils. Among organic residues, sunflower residue showed high sorption and low desorption of P in soils, indicating a higher potential of this organic residue for P retention and reducing surface and groundwater contamination in calcareous soils. 相似文献
2.
Using young fruits or fruit segments, rates of penetration of 45CaCl2 across apple fruit cuticles (Malus x domestica) were studied during fruit development in two consecutive years (’?Golden Delicious’ in 2000, ’?Cox Orange Pippin’ and ’?Boskoop’ in 2001). The aqueous donor solutions contained 5 g l—1 CaCl2 and 0.2 g l—1 Glucopon 215 CSUP as wetter. A droplet (5 μl) was applied to each fruit disc and allowed to dry within 1 h. Amounts penetrated were estimated immediately after droplet drying (0 h) and after 6 and 24 h penetration, respectively. Temperature during penetration was 20 ?C and 100 % humidity was maintained throughout the experiment, once the droplet had dried. Rates of penetration were greatly affected by the stage of fruit development. With all varieties tested, highest rates were measured during the early stages of fruit development (before June drop) when approx. 100 % of the CaCl2 applied penetrated within 24 h. After June drop, when trichomes had vanished and most stomata developed into lenticels, penetration rates decreased rapidly and large variability among the samples developed. This pattern was similar with all three varieties. The involvement of trichomes, stomata, and lenticels as preferential sites of penetration of calcium chloride across the apple fruit cuticles is discussed. Using a model calculation, it is argued that ten or more spray applications are needed to significantly increase calcium contents of apples. This has two causes: Only a small fraction of the spray liquid is intercepted by the fruits, and penetration can be rather slow. 相似文献
3.
Hamburg A Puvanesarajah V Burnett TJ Barnekow DE Premkumar ND Smith GA 《Journal of agricultural and food chemistry》2001,49(1):146-155
The fate of 2,4-dichlorophenoxyacetic acid (2,4-D) applied foliarly as the 2-ethylhexyl ester (EHE) to wheat and potatoes, to the soil as the dimethylamine (DMA) salt under apple tree canopies, and preplant as the free acid for wheat, lettuce, and radish was studied to evaluate metabolic pathways. Crop fractions analyzed for (14)C residues included wheat forage, straw, and grain; potato vine and tubers; and apple fruit. The primary metabolic pathway for foliar application in wheat is ester hydrolysis followed by the formation of base-labile 2,4-D conjugates. A less significant pathway for 2,4-D in wheat was ring hydroxylation to give NIH-shift products 2,5-dichloro-4-hydroxyphenoxyacetic acid (4-OH-2,5-D), 4-OH-2,3-D, and 5-OH-2,4-D both free and as acid-labile conjugates. The primary metabolic pathway in potato was again ester hydrolysis. 2,4-D acid was further transformed to 4-chlorophenoxyacetic acid and 4-OH-2,5-D. For the soil applications, (14)C residues in the crops were low, and characterization of the (14)C residues indicated association with or incorporation into the biochemical matrix of the tissue. The degradative pathways observed in wheat are similar to those characterized in other intact plant studies but differ from those in studies in wheat cell suspension culture in that no amino acid conjugates were observed. 相似文献
4.
5.
The persistence and degradation of chlorothalonil and chlorpyrifos in a cranberry bog 总被引：1，自引：0，他引：1
The effect of a spray-tank adjuvant on the persistence, distribution, and degradation of two pesticides, chlorothalonil and chlorpyrifos, was studied in a commercial cranberry bog. Pesticides were applied according to label instructions to cranberry plants in paired plot studies. Dislodgeable foliar and whole fruit residues of both pesticides and several degradation products were assessed over a growing season. Residues were also assessed in soil samples collected at fruit harvest. Adjuvant increased both fruit and foliar residues but did not significantly alter the dissipation rate or metabolism of either pesticide. The dissipation of dislodgeable foliar chlorothalonil and chlorpyrifos residues followed first-order kinetics, with estimated half-lives of 12.7 and 3.5 d, respectively. All residue levels on harvested fruit were well below the current U.S. EPA tolerances for fresh cranberries. Chlorothalonil (58%) was the major residue in fruit at harvest (76 d post-chlorothalonil application), with 4-hydroxy-2,5,6-trichloroisophthalonitrile and 1,3-dicarbamoyl-2,4,5,6-tetrachlorobenzene accounting for 26% and 6% of the total residues, respectively. Degradation products accounted for 88% of the total chlorothalonil residues in soil at fruit harvest. The products 1,3-dicarbamoyl-2,4,5,6-tetrachlorobenzene, 1-carbamoyl-3-cyano-4-hydroxy-2,5,6-trichlorobenzene, 2,5,6-trichloro-4-methylthioisophthalonitrile, and 2,4,5-trichloroisophthalonitrile have not been previously identified in cranberry bog environments. Chlorpyrifos was detected in fruit at harvest (62 d post-chlorpyrifos application), but no metabolites were found. Chlorpyrifos-oxon and 3,5,6-trichloro-2-pyridinol, however, were detected in earlier fruit samples and in foliage and soil samples. 相似文献
6.
Several levels of both selenite and selenate were incubated with separate samples of soil for periods of up to 30 d and at temperatures between 5 and 60°C. The concentrations of selenite or of selenate which caused neither desorption nor further sorption–that is, the null-point concentrations–were then measured at 25°C. In addition, the rate of desorption was measured after incubation at 60°C for 10 d. The ability of a mechanistic model to describe the results was tested.
There were large decreases in the null-point concentrations of selenite with both increasing period and increasing temperature of incubation. These effects were modelled as due to a relatively rapid diffusive penetration and a large activation energy for diffusion. Only a small proportion of the sorbed selenite was desorbed within 3 d but, at large solution:soil ratios, desorption appeared to be still continuing. These effects were fairly well predicted by the model applied to the sorption data. For example, the continuing desorption was ascribed to the slow reversal of the diffusive penetration. For selenate, the effects of period and temperature of incubation were much smaller. These effects were modelled as due to a slower diffusive penetration and a lower activation energy. Desorption was quicker and was more nearly complete. According to the model, a large proportion remained in the adsorbed form and was more quickly removed when desorption was induced. It is argued that the behaviour of selenite is consistent with diffusion into a crystal and the large activation energy is required to enable jumps over energy barriers. On the other hand, the lower activation energy for selenate is consistent with diffusion being limited to pores or cracks.
It is suggested that the residual value of selenite fertilizers would decrease because of the continuing reaction, but that this effect would be unimportant for selenate. 相似文献
There were large decreases in the null-point concentrations of selenite with both increasing period and increasing temperature of incubation. These effects were modelled as due to a relatively rapid diffusive penetration and a large activation energy for diffusion. Only a small proportion of the sorbed selenite was desorbed within 3 d but, at large solution:soil ratios, desorption appeared to be still continuing. These effects were fairly well predicted by the model applied to the sorption data. For example, the continuing desorption was ascribed to the slow reversal of the diffusive penetration. For selenate, the effects of period and temperature of incubation were much smaller. These effects were modelled as due to a slower diffusive penetration and a lower activation energy. Desorption was quicker and was more nearly complete. According to the model, a large proportion remained in the adsorbed form and was more quickly removed when desorption was induced. It is argued that the behaviour of selenite is consistent with diffusion into a crystal and the large activation energy is required to enable jumps over energy barriers. On the other hand, the lower activation energy for selenate is consistent with diffusion being limited to pores or cracks.
It is suggested that the residual value of selenite fertilizers would decrease because of the continuing reaction, but that this effect would be unimportant for selenate. 相似文献
7.
Ji-Hoon Kim Won Sik Shin Dong-Ik Song Sang June Choi 《Water, air, and soil pollution》2005,166(1-4):367-380
Single- and bi-solute sorption and desorption of 2,4-dichlorophenol (2,4-DCP) and 2,4,5-trichlorophenol (2,4,5-TCP) in montmorillonite modified with hexadecyltrimethylammonium (HDTMA) were investigated using multi-step sorption and desorption procedure. Effect of pH on the multi-step sorption and desorption was investigated. As expected by the magnitude of octanol-water partition coefficient, K ow , both sorption and desorption affinity of 2,4,5-TCP was higher than that of 2,4-DCP at pH 4.85 and 9.15. For both chlorophenols, the protonated speciation (at pH 4.85) exhibited a higher affinity in both sorption and desorption than the predominant deprotonated speciation (about 95% and 99% of 2,4-dichlorophenolate and 2,4,5-trichlophenolate anions at pH 9.15, respectively). Desorption of chlorinated phenols was strongly dependent on the current pH regardless of their speciation in the previous sorption stage. Freundlich model was used to analyze the single-solute sorption and desorption data. No appreciable desorption-resistant (or non-desorbing) fraction was observed in organoclays after several multi-step desorptions. This indicates that sorption of phenols in organoclay mainly occurs via partitioning into the core of the pseudo-organic medium, thereby causing desorption nearly reversible. In bisolute competitive systems, sorption (or desorption) affinity of both chlorophenols was reduced compared to that in its single-solute system due to the competition between the solutes. The ideal adsorbed solution theory (IAST) coupled to the single-solute Freundlich model successfully predicted bisolute multi-step competitive sorption and desorption equilibria. 相似文献
8.
Development of apple superficial scald, soft scald, core flush, and greasiness is reduced by MCP. 总被引：23，自引：0，他引：23
1-Methylcyclopropene (MCP) was used to evaluate the role of ethylene in development of apple (Malus x domestica Borkh.) physiological disorders during storage. Granny Smith, Red Chief Delicious, and Fuji apple fruit were treated with MCP at a concentration of 1 microL L(-)(1) for 12 h at 20 degrees C. For all varieties stored at 0 degrees C, ethylene production and respiration rates were reduced for several months following MCP treatment, and firmness and titratable acidity of treated fruit were higher compared to controls. Apples treated with MCP did not develop superficial scald or peel greasiness through 6 months storage plus ripening at 20 degrees C for 7 days. Core flush was not observed in MCP-treated fruit until 6 months after treatment when the incidence was still lower compared to control fruit. MCP delayed the rise in production of alpha-farnesene and reduced accumulation of its oxidation products. 相似文献
9.
土壤中黑碳对农药敌草隆的吸附-解吸迟滞行为研究 总被引：6，自引：0，他引：6
采用批处理振荡法和连续稀释法分别测定了敌草隆在人工添加黑碳土壤和自然形成的不同有机质和黑碳含量的土壤中的吸附一解吸行为。吸附结果表明，人工添加黑碳的土壤对敌草隆的吸附强度和吸附容量以及吸附等温线的非线性均随土壤黑碳添加浓度的增加而逐步增大；自然土壤的吸附容量和吸附强度随土壤总有机质含量增加而增加，但吸附等温线的非线性则与土壤中黑碳对有机质的相对含量有关，黑碳比例越高，等温线非线性越大。解吸实验结果表明，无论是人工添加黑碳的土壤还是自然土壤，对敌草隆的解吸迟滞作用均随土壤黑碳含量增高而愈明显。 相似文献
10.
The effect of two ethoxylated rapeseed oils (RSO) as surfactants for foliar-applied calcium chloride CaCl2 and calcium acetate Ca(CH3COO)2 on deposit characteristics, penetration, and calcium (Ca) residues after rainfall was investigated in columnar apple trees (CAT, Malus domestica Borkh.) and apple seedlings. Irrespective of salt and apple variety, both surfactants enhanced droplet spreading and led to a greater area covered by calcium within the droplet residues. The addition of the rather lipophilic surfactant RSO 5 and the rather hydrophilic RSO 60 increased penetration of Ca from both salts through isolated apple leaf cuticular membranes. Our data demonstrate that penetration is better reflected by area covered with calcium than by droplet spreading area. Considering the point of deliquescence (POD) from the salts and results of cuticular Ca penetration, we postulate that in case of CaCl2 reduction of wash-off was due to enhanced penetration, whereas for Ca(CH3COO)2 wash-off was decreased due to distinct enhancement of rainfastness. 相似文献
11.
An indirect competitive enzyme-linked immunosorbent assay (ELISA) was used to determine photochemically cutin-bound residues of chlorothalonil in enzymatically isolated tomato and apple fruit cuticles. The samples were spiked, irradiated, exhaustively extracted, and depolymerized with boron trifluoride complex resulting in a soluble depolymerisate. With this procedure, the ELISA could be calibrated with free target molecules for the quantification of originally bound chlorothalonil residues. In fruit cuticles that were irradiated for 8 h by simulated sunlight, 0.030 and 0.068 mg/g photoinduced cutin-bound residues of wax-free cuticles (calculated as chlorothalonil) were determined for tomatoes and apples, respectively. For the used antibody mAb chl. 4/11, cross-reactivities with derivatives of chlorothalonil simulating different types of cuticle-bound residues are given and discussed. 相似文献
12.
苹果果实中毒死蜱残留的品种间差异及套袋对毒死蜱残留的影响 总被引：1，自引：0，他引：1
为探讨苹果果实中毒死蜱残留的品种间差异及套袋对其残留的影响作用,采用气相色谱法（GC-FPD）,研究了不同品种苹果果实中毒死蜱的残留动态以及套袋对苹果果实不同部位中毒死蜱残留的影响。结果表明,毒死蜱在苹果果实中的残留量存在着明显的品种差异,其中红富士属于高农药残留的品种,而嘎拉、红将军和83-1-70-3则属于低农药残留的品种。毒死蜱在苹果果实不同部位中的残留量表现出明显差异,果皮是毒死蜱残留的主要部位,其次是全果,果肉中的残留最少。套袋明显减少了毒死蜱在苹果果实中的残留量,不论处理浓度和取样时间如何,套袋苹果果实中毒死蜱的残留量比不套袋至少减少1/3。 相似文献
13.
Testing a mechanistic model. II. The effects of time and temperature on the reaction of zinc with a soil 总被引：2，自引：0，他引：2
N. J. BARROW 《European Journal of Soil Science》1986,37(2):277-286
Samples of a soil were mixed with zinc nitrate solutions and incubated from 1 to 30 days at temperatures from 4 to 60°C. The solution concentration of zinc, which would not have changed on brief mixing with the soil at 25°C, was measured. Background electrolytes for this measurement of null-point concentration were both calcium and sodium nitrate. The effect of the temperature at which null-point concentration was measured was also investigated. After incubation with zinc nitrate, desorption of zinc, and sorption of further zinc, were measured. Null-point concentration of zinc decreased with increasing period of incubation, with the rate of decrease greatest at high temperatures of incubation. The effects of both temperature and time were closely described by a model which postulated an initial rapid adsorption of ZnOH+ ions onto heterogenous charged surfaces, followed by a diffusive penetration. Increasing the temperature of incubation increased the rate of diffusive penetration and led to low solution concentrations. In contrast, increasing the temperature at which null-points were measured increased the concentration of ZnOH+ ions. This was shown to be consistent with a change in position of the equilibrium of the initial, rapid, adsorption reaction. Curves for desorption of zinc were continuous with curves for sorption of further zinc, but neither desorption nor further sorption coincided with the position of the curves relating retention of previously added zinc to concentration. This result was consistent with the model and occurred because desorption must reverse diffusive penetration. However, the model under-predicted the magnitude of both desorption and sorption of further zinc. Desorption in calcium solutions was greater than in sodium solutions, even when the solution concentration of zinc approached zero. This was consistent with exchange diffusion of calcium ions for some of the penetrated zinc. 相似文献
14.
Immobilization of Cd in contaminated soil is a technique to improve soil quality. Zeolites are potentially useful additives to bind heavy metals. This study examines the influence of decreasing the grain size of raw zeolitic tuff to the nano‐range on Cd sorption‐desorption isotherms in a sandy soil. The aim was to evaluate the feasibility of using nanoparticulate zeolitic tuff as a sequestering agent for Cd in soil. Sorption and desorption of Cd on zeolitic nanotuff was investigated in batch experiments. The sandy soil was amended with zeolitic nanotuff, synthetic Al oxide nanoparticles, or raw zeolitic tuff. After a 48 h sorption step, three desorption steps were induced using the sequential dilution method. The measured sorption‐desorption data were adequately described by the Freundlich equation. A nonlinear two‐stage one‐rate model matched well with measured Cd sorption‐desorption isotherms of zeolitic nanotuff, raw zeolitic tuff, Al oxide nanoparticle, and control soil. The batch experiments demonstrated the strong influence of pH on Cd sorption. Zeta‐potential measurements of zeolitic nanotuff indicated that electrostatic interaction was important for sorption. Soil amended with zeolitic nanotuff showed the lowest hysteresis index based on the differences obtained from sorption‐desorption isotherms regarding the amount of Cd sorbed. The index decreased with increasing metal concentration. For soil amended with nanoparticulate zeolitic tuff, the estimated Freundlich coefficient was 4 orders of magnitude higher than in the control soil and 2 orders of magnitude higher than the soil amended with raw zeolitic tuff. In addition, this sorbent decreased the amount of Cd released after three desorption steps by up to 12 and 7 times compared to the control soil and the soil amended with raw zeolitic tuff, respectively. The effect on Cd sorption of grinding the raw zeolitic tuff to the nanorange was considerably more pronounced than the effect of raw zeolitic tuff. 相似文献
15.
Mahdi Najafi Ghiri Mahrooz Rezaei Abdolmajid Sameni 《Archives of Agronomy and Soil Science》2013,59(9):945-957
Zinc sorption–desorption by sand, silt and clay fractions of six representative calcareous soils of Iran were measured. Sand, silt and clay particles were fractionated after dispersion of soils with an ultrasonic probe. Zinc sorption analysis was performed by adding eight rates of Zn from 6 to 120 μmol g?1. For the desorption experiment, samples retained after the measurement of Zn sorption were resuspended sequentially in 0.01 M NaNO3 solution and shaken for 24 h. Results indicated that Zn sorption by soil fractions increased in the order clay > silt > sand, and correlated negatively with CaCO3 content and positively with cation exchange capacity (CEC) and smectite content. Results indicated that for all fractions, the Langmuir equation described the sorption rates fairly well. In contrast to sorption, Zn desorption from soil fractions increased in the order sand > silt > clay, and correlated positively with CaCO3 content, CEC and smectite content. Results showed that parabolic diffusion and two constant equations adequately described the reaction rates of Zn desorption. In general, for all soils studied, the coarser the particle size, the less Zn sorption and more Zn desorption, and this reflects much higher risk of Zn leaching into groundwater or plant uptake in contaminated soils. 相似文献
16.
在黄土高原陕西省长武塬区选取品种和管理手段均相同的3种林龄果园(尚未结果的5年幼龄果园、已结果的8年初果园和13年壮果园)苹果树,采用空间换时间的试验设计,分别于2015年7月12日和8月19日对0—500cm深度土壤及对应取样处的苹果树枝条取样,测定土样和枝条样中水分的稳定氢氧同位素,并利用贝叶斯模型量化降水前后不同土层对苹果林耗水的贡献。结果表明:(1)不同林龄苹果树降雨前后的主要水分来源深度不同。干旱时,13年壮龄果树的主要吸水深度比5年和8年果树深;而生长旺季,雨季降水只能补充未挂果的5年幼龄果园土壤水分消耗,即使降水量很大,也无法满足已经开始挂果的8年和13年果园土壤水分消耗。(2)在干旱期,5年和8年果树50%以上的水分来自表层0—100cm土壤,而13年果树50%的水分来自100—300cm土层。而降水后,5年和8年果树的主要水分来源变为100—300cm土层,贡献值在40%左右;13年果园的主要水分贡献层为0—100cm土层,贡献了近50%的水分。(3)3种林龄果树根系对300—500cm土层土壤水分的吸收对降雨的响应非常弱,降雨前后贡献率始终保持在30%。 相似文献
17.
We compared rates of desorption of heavy metals from goethite, an important soil constituent, in order to understand the mechanisms of sorption and desorption better. Samples of goethite were reacted with salt solutions of heavy metals for 2 hours or for 8 weeks. The metals were Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb. Desorption was then induced by successive treatments with 0.7 m HNO3 for up to 360 hours followed by complete dissolution of the goethite particles. After brief sorption (2 hours), a large proportion of the sorbed metals was desorbed by brief treatment (15 minutes) with HNO3. This suggests that the metals were mainly sorbed on, or close to, external goethite surfaces. After longer sorption (8 weeks), even 360 hours of extraction with 0.7 m HNO3 did not recover all of the sorbed metals. Complete dissolution of the goethite particles was necessary. This suggests that the eight heavy metals had penetrated the goethite particles deeply. When desorption was summarized using a pragmatic equation, it was only for brief sorption followed by brief desorption that indices of the rate of desorption were well correlated with measures of the rate of sorption as obtained in an earlier work. When desorption was described with a mechanistic model, observed desorption was often faster than predicted and the discrepancy was greatest with the shorter periods of desorption. The discrepancy was marked for Ni, Cr and Co. We think this was because large portions of these metals were incorporated into the goethite structure by lattice diffusion and were therefore held close to the surface. When the acid dissolved some of the goethite these metals were released. For long‐term desorption and for most metals, the ratio of observed to predicted desorption decreased with increasing ionic radius. We think that this reflects a changing balance between lattice and pore diffusion, with lattice diffusion more important for metals with radii near that of Fe (Cr, Co, Ni), and pore diffusion more important for the larger cations of Cd and Pb. Manganese was an exception. Desorption was at first faster than predicted but then declined to be close to predicted values. This suggests that Mn mostly penetrated more deeply by pore diffusion. 相似文献
18.
采用批量平衡实验法研究了四氯乙烯和萘在过氧化氢氧化前后含水层土壤上的吸附。原土经过氧化氢处理后有机质含量明显降低,但是处理前后的土样对四氯乙烯和萘的吸附差别极小。过氧化氢对原土中极性官能团的破坏使原土中的大分子有机质变为小分子的可溶性有机质离开体系,造成土壤有机质含量降低。这些具有极性官能团的大分子有机质对研究的两种化合物的吸附贡献很小。在调节液固比使各种单一体系中的液相浓度差异达到一至两个数量级的情况下,加标解吸体系下的等温线仍表现为非常规的近似水平线,说明液相浓度的降低不足以使土壤中吸附的化合物发生解吸。这一结果从另一侧面说明两种目标物在研究土壤上的吸附是以在致密有机相上的吸附为主,而这部分有机质不会被过氧化氢所氧化。因此,在评估污染土壤对地下水的危害时,需慎重使用通过吸附实验得到并基于有机质总量的分配系数。 相似文献
19.
水肥一体化技术对不同生态区果园苹果生产的影响 总被引：11，自引：0，他引：11
为探究水肥一体化技术对陕西省不同生态区苹果生产的影响,分别选取渭北旱塬区和关中平原区典型‘红富士’苹果园,研究了相同肥料用量的NPK传统施肥[NPK(C)]、NPK水肥[NPK(F)]和肥料用量减半的NPK水肥[1/2NPK(F)]对苹果产量、品质、肥料利用效率、果实养分吸收和果园经济效益的影响。结果表明,因不同生态区环境条件和果园自身土壤和肥力等存在差异,水肥一体化技术对苹果生产的影响也不同。渭北旱塬区果园,与NPK(C)相比,NPK(F)处理苹果增产13.0%,果实硬度增加10.6%,糖酸比提高19.1%,化肥偏生产力(PFP)由18.2 kg·kg?1提高至36.3 kg·kg?1,果实N、P和K养分吸收量分别增加36.0%、75.3%和44.8%;1/2NPK(F)处理对苹果生产的影响基本不显著。关中平原区果园,与NPK(C)相比,1/2NPK(F)使苹果增产26.2%,糖酸比提高16.9%,PFP从27.2 kg·kg?1提高至68.7 kg·kg?1,果实N、P和K养分吸收量分别增加41.8%、98.9%和58.9%;然而,NPK(F)处理苹果仅增产14.1%,果实养分吸收无显著增加,品质亦无明显改善。经济收益方面,在相同肥料用量下,采用水肥一体化技术可使渭北旱塬区和关中平原区果园分别增收1.55万元·hm?2和3.65万元·hm?2;当肥料用量减半时,收益增加分别为0.21万元·hm?2和7.28万元·hm?2。总体而言,在陕西渭北旱塬区和关中平原区果园采用水肥一体化技术均能显著提高苹果产量和改善品质,但其效果存在明显差异,实践中需因地制宜,根据果园实际情况,采用适宜的水肥用量以求达到高产、高效和优质的目标。 相似文献
20.
Apple (Malus x domestica Borkh., cv. Gala) fruit treated with 0.5 microL x L(-1) 1-methylcyclopropene (MCP) or air (non-MCP) for 12 h at 20 degrees C were exposed to gamma radiation at doses of 0, 0.44, 0.88, or 1.32 kGy at 23 degrees C and then stored at 20 degrees C. Production of volatile compounds was measured on the day of irradiation and 1, 3, 7, 14, and 21 days after irradiation. Both MCP treatment and irradiation inhibited ethylene production. MCP treatment reduced production of all volatile esters and alcohols detected, whereas irradiation inhibited production of most, but not all, esters and some alcohols by non-MCP-treated fruit. The inhibition of volatile production following irradiation increased with dose. Production of methyl and propyl esters was inhibited more than that of other esters following irradiation or MCP treatment. The impact of irradiation on production of esters and alcohols by MCP-treated fruit was minimal. Non-MCP-treated fruit irradiated at 0.44 kGy produced the most esters during the 21-day period at 20 degrees C following irradiation, and the ester production rate in these fruit was comparable to that of the nonirradiated fruit 21 days after irradiation. Fruit treated with doses higher than 0.44 kGy did not recover their ability to produce volatile compounds. These results indicate both MCP and ionizing radiation inhibit production of many aroma compounds produced by ripening apple fruit. 相似文献