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1.
Potassium (K) is one of the major mineral elements required for normal growth of cotton. However, understanding the effect of controlled‐release K fertilizer on leaf photosynthesis and K use efficiency (KUE) of cotton is currently limited. A two‐year pot experiment was consecutively conducted in 2014 and 2015 with three kinds of K fertilizer including K2SO4, KCl, and polymer‐coated KCl (CRK), each at four application rates (0.00, 0.86, 1.73, and 2.59 g K plant−1, respectively). For each type of K fertilizer, the yield and K uptake of cotton increased but the KUE decreased with higher K fertilizer application. The release characteristics of K from CRK corresponded well to the K requirements during cotton growth. Plant‐available soil K, as well as leaf SPAD values, net photosynthetic rate (Pn), maximal photochemical efficiency (Fv/Fm), and effective quantum yield of photosystem II (ΦPSII) in CRK treatments were increased after full bloom stage compared to conventional K fertilizers under the same potassium application rate. Consequently, the CRK treatments significantly increased lint cotton yields by 8.1–32.7% and 3.7–20.8%, while the KUE increased by 15.5–54.8% and 14.5–45.4% compared to KCl and K2SO4 treatments, respectively. The results indicate that the application of CRK is intensively recommended to replace conventional potassium fertilizers for gaining greater yields and higher KUE of cotton.  相似文献   

2.
Potassium (K) is one of the major essential nutrient elements whose application of organic or nano-chelate-fertilizers has received increased attention recently. Cadmium (Cd) contamination in agricultural soils and environment is increasing due to the over-application of Cd-containing phosphate fertilizers. But few studies have been carried out on the environmental influences of K-nano-chelate fertilizers especially on Cd-polluted soils. Therefore, the effects of K-fertilizer application in different rates (0, 100 and 200 mg kg?1 soil) and forms (KCl, K2SO4 and K-nano-chelate) on Cd content and partitioning in Ocimum basilicum grown on an artificially Cd-contaminated calcareous soil (with 40 mg Cd kg?1 soil) were studied under greenhouse conditions. Cadmium decreased shoot dry weight (SDW), but did not affect root dry weight (RDW) and no consistent trend was observed with applied K. Cadmium increased shoot and root Cd concentration or uptake. KCl and K2SO4 increased shoot Cd concentration compared to that of control, whereas K-nano-chelate did not affect it. In Cd-treated soils the mean value of Cd translocation factor (ratio of Cd concentration in shoots to that of roots) decreased by 60% as compared to that of the control. Application of 100 mg K-K2SO4 and 100 and 200 mg K-nano-chelate increased the Cd translocation factor by 49, 59 and 112% in Cd-treated soils, respectively. In Cd-treated soils, greater amounts of Cd accumulated in roots. K-nano-chelate could mitigate the adverse effect of Cd on SDW and Cd accumulation in plants grown on Cd-polluted soils, so the risk of Cd entrance to the food chain is reduced (however, in Cd-untreated soils, K-nano-chelate increased the Cd translocation factor higher than other K sources). In Cd-polluted soils KCl was the most inappropriate fertilizer that may intensify Cd accumulation in plants. However, it may be useful in the phytoremediation of Cd-polluted soils.  相似文献   

3.
二种钾肥对海泡石钝化修复镉污染土壤效应影响的研究   总被引：2，自引：0，他引：2  
为了揭示钾肥对Cd污染土壤钝化修复效果的影响,为土壤钝化修复过程中合理施钾肥提供理论依据。本文选取不同剂量(含量以K2O计算,分别为0.1 g·kg~(-1)、0.2 g·kg~(-1)和0.3 g·kg~(-1))的KCl和K_2SO_4作为典型钾肥,以海泡石(10 g·kg~(-1))作为钝化材料,通过油菜盆栽试验,研究了两种钾肥在海泡石钝化条件下对Cd污染土壤修复效应的影响。结果表明:K_2SO_4显著增加了油菜的生物量,其增幅为6.06%~10.05%。与单施海泡石钝化相比,在海泡石钝化时施用KCl和K_2SO_4两种钾肥,油菜地上部茎叶Cd含量分别增加16.38%~60.73%和15.62%~25.19%;施用KCl和K_2SO_4对土壤p H未产生显著性影响,却显著地增加了土壤有效态Cd含量,其增幅分别为25.51%~34.65%和18.5%~24.96%。添加海泡石可使土壤的Zeta电位向负值方向移动,提高土壤对Cd的负载能力;但添加海泡石下施用KCl和K_2SO_4均能提高土壤的Zeta电位,降低土壤对Cd的负载能力。等温吸附试验同样表明,添加KCl和K_2SO_4均能降低海泡石对Cd的吸附量,在水溶液中海泡石对Cd的最大吸附量为5.30 mg·kg~(-1),添加KCl和K_2SO_4后吸附量分别降低至2.87 mg·g~(-1)和4.92 mg·g~(-1)。KCl和K_2SO_4显著改善了土壤中K、Mn、Cu和Zn等营养元素的有效态含量。从上述结果可以发现,在海泡石钝化修复Cd污染土壤过程中,施K_2SO_4对钝化效果的影响小于施KCl。  相似文献   

4.
Abstract

Groundnut (Arachis hypogae L.) is the most important oilseed crop of India and it is abundantly grown under rainfed conditions in vertisols of Western India. The objective of this work was to study the effect of potassium (K) basal and foliar fertilization on yield, nutrient concentration in tissue and quality parameters of groundnut. Two varieties, GAUG‐1 (bunch type) and GAUG‐10 (spreading type) were grown during Kharif (rainfed) and Rabi (irrigated) seasons at Junagadh, Gujarat. The experiment compared two foliarapplied K fertilizers (KCl and K2SO4) at two different doses (0.5 and 1.0%) with basal KCl application (0 and 50 kg K2O ha?1). Field soil was highly calcareous (pH 8.2, NH4OAc extractable K 188 kg ha?1 with 40% lime reserve) Vertic ustochrept. The results showed a significant response in pod yield with foliar and soil‐applied potassium as compared to the control treatment. Pod yields were significantly higher when basal and foliar applications were combined. The best results were achieved with foliar application of 1% KCl together with a basal fertilization with 50 kg K2O ha?1. Response to foliar‐applied K was higher in rainfed kharif crop than in irrigated rabi crop. Groundnut variety GAUG‐10 out yielded GAUG‐1. Foliar K application increased plant tissue concentration of K. Foliar fertilization with KCl and K2SO4 did not cause leaf burn. Potassium application improved the crop harvest index and grain quality parameters of boldness, protein and oil contents. Response to K in quality parameters of protein and oil contents of seed was more consistent with foliar applied K2SO4 . The results confirmed that the practice of foliar K nutrition when used as a supplement and not a substitute for standard soil fertilization, is beneficial for groundnut crop in Western India.  相似文献   

5.
Abstract

The main objective of this study was to determine the efficacy of cement kiln flue dust as a substitute for potassium sulfate fertilizer. Chemical and X‐ray diffraction analyses revealed that the flue dust contained about 20.7% K of which 9.1% was present as aphthitalite (K3Na(SO4)2) , 4.4% as sylvite (KCl) and the remaining 7.2% as arcanite (K2SO4) . Accordingly, about 80% of the potassium in the dust was present as sulfates, though it contained 30% total sulfate and 15% Ca.

The effects of flue dust were compared to some or all of the following fertilizers: KCl, K2SO4 and a synthetic fertilizer, on 11 soils ranging in texture from sand to clay in three greenhouse experiments. The synthetic fertilizer was made from K2SO4 and CaSO4.2H2O which were applied at the same rate of K and Ca as contained in the flue dust. The experimental results show that flue dust is as effective a K source as any of the fertilizers tested as it increased potato, barley and alfalfa yields and tissue and soil K concentrations to the same level. Furthermore, the flue dust increased the tissue sulfur concentration and the quantities of available sulfate in soils to the same level as potassium sulfate. Finally, the Ca contained in flue dust increased the concentration of this element in potato tops and soils when grown on eight coarse textured soils. The flue dust had, however, no effect on soil pH on any of the soils tested.  相似文献   

6.
钾肥用量和品种对桑叶生产及蚕茧质量的影响   总被引：3，自引：0，他引：3  
通过为期 4年的田间施肥试验和 1季养蚕试验 ,研究了钾肥用量和钾肥品种对桑叶产量、品质、养分吸收和蚕茧质量的影响。结果表明 ,施K2 O 1 5 0、30 0、375kghm-2 a-1 处理分别比不施K肥年均增产桑叶 2 3.9%、31 .7%、36 .0 %;等量钾肥时 ,KCl对桑叶增产效果基本等同于K2 SO4;施钾增产效果有逐年增加趋势 ,同时钾肥施用表现后效。施钾明显提高桑叶中N、K和S(K2 SO4为钾源时 )含量 ,而降低Ca、Mg和Zn含量 ,对P含量影响不大。结果显示 ,钾肥施用大幅度促进了桑树对各种养分的吸收 ,从而提高了肥料利用率。施钾明显促进桑叶品质的改善 ,随着钾肥用量增加 ,桑叶中必需氨基酸、氨基酸总量、蛋白质、糖分和油脂含量均呈增加趋势。KCl施用也能提高桑叶品质 ,但效果比K2 SO4差。蚕茧质量测试结果表明 ,桑树施钾后对喂养的蚕茧品质产生正面影响 ,蚕重、全茧量、上茧率、茧丝长、解舒率、茧丝净度等指标均因施钾而提高 ,高量钾比低量钾效果好 ,在等量钾用量时K2 SO4对蚕茧质量的促进作用明显好于KCl。  相似文献   

7.
不同钾肥对再生水灌溉条件下土壤-作物系统Cd的影响   总被引：3，自引：0，他引：3  
为了探明再生水灌溉条件下不同施钾肥处理对土壤-作物系统Cd的影响及差异性,通过田间微区试验研究了不同施钾肥处理对再生水灌溉番茄植株、果实以及根际土与非根际土Cd含量的影响。结果表明:再生水灌溉条件下,施钾肥处理可提高番茄果实产量,施加KCl较K2SO4增产效果明显,分别较不施肥处理可增产6.10%～24.00%和1.36%～13.16%;不施钾肥较不施肥处理番茄果实Cd含量降低,但降低幅度小于施加钾肥处理,施加KCl较K2SO4处理番茄果实Cd含量较低,Cd含量分别较不施钾肥处理分别减少58.33%和8.33%,且各处理均未超0.05mg/kg的限值标准;不施钾肥处理较不施肥处理土壤pH、Cd含量有所降低,降低幅度小于施钾肥处理,有效态Cd有所增加,施加KCl和K2SO4较不施肥处理有效态Cd降低,施加KCl和K2SO4较不施钾肥处理根际土和非根际土pH、Cd含量和有效态Cd含量均有所降低,其中施加KCl根际土和非根际土Cd含量分别降低2.96%～3.11%和5.75%～14.22%,施加K2SO4分别降低4.14%～5.90%和8.10%～8.29%;施加KCl根际土和非根际土有效态Cd含量分别降低10.75%～16.19%和13.98%～28.74%,施加K2SO4分别降低15.97%～20.55%和19.91%～24.70%。因此,再生水灌溉条件下,可通过选择施加适宜的钾肥种类,调控重金属Cd在土壤-作物系统的分布及其生物有效性,施加K2SO4较KCl相比,可一定程度降低土壤Cd全量及有效态Cd含量。  相似文献   

8.
The quality of green tea is highly dependent on the concentration of free amino acids, whose profile is dominated by the unique amino acid theanine (N5‐ethyl‐glutamine). A high quality is associated with a high amino acid–to–catechin ratio, but previous results indicated that excessive chloride (Cl–) supply is detrimental for amino acid accumulation. Several experiments were conducted to investigate the effect of chloride on growth and concentrations of free amino acids in young tea plants. Soil‐grown tea plants supplied with different levels of potassium (K) as K2SO4 or KCl exhibited increased concentrations of free amino acid in young shoots only when supplied with K2SO4, and the negative effect of KCl supply was mainly due to a reduced concentration of theanine. Concentrations of other nutrients in plant tissues were not influenced. The uptake of Cl– and its interaction with nitrogen (N) uptake were further investigated in a second experiment, in which soil‐cultivated tea plants were supplied with varying amounts of Cl–. Chloride application reduced yield of young shoots, and severity of leaf damage was related to the concentration of Cl– in leaves. Nitrogen uptake was reduced by Cl– addition. To verify whether the decrease of free amino acids was simply a result of inhibited NO assimilation, a third experiment was conducted, in which tea plants were NH ‐fed in the absence or presence (equivalent to the NH concentration) of Cl–. Again, concentrations of theanine and total free amino acids in young shoots were reduced by Cl– supply, but changes of the free–amino acid pool did not contribute to the maintenance of charge balance. However, concentration of theanine in roots, where it is synthesized, was not influenced by Cl–. Total N concentrations of roots and mature leaves, uptake rate of NH , and activity of glutamine synthetase in fibrous roots and young leaves were all unaffected by Cl– as well. It is suggested that translocation of theanine from root to shoot and its catabolism in young shoots might be influenced by Cl–.  相似文献   

9.
Abstract

Though there exists a wide spectrum of sulfur‐oxidizing microorganisms in soils, the oxidation rate of soil‐applied elemental sulfur (S0) is regularly limited because of a restricted population size. An incubation experiment was conducted to determine the effect of repeated S0 applications on different microbial populations, sulphate (SO4 2?)‐S concentration, and soil pH. Elemental sulfur was applied repeatedly at a rate of 15 mg S g?1 soil in a 15‐day interval cycle of 7 times. After each cycle, 7.5 mg lime (CaCO3) g?1 soil was applied to adjust the soil pH to an optimum range. Soil pH and 0.025 M potassium chloride (KCl)–extractable SO4 2?‐S were determined every 3 days. The population of Thiobacillus spp. and aerobic heterotrophic sulfur‐oxidizing bacteria were counted 3 and 15 days after each S0 application. The results showed that the soil pH decreased rapidly from an initial value of 7.6 to 5.3, 15 days after the first S0 application. Lime applications successfully counterbalanced the acidifying effect of S0 oxidation, and soil pH values were maintained in the optimum range with a pH of about 6.4. The 0.025 M KCl–extractable SO4 2?‐S content increased with repeated applications of S0, showing a maximum value of 3,800 mg S kg?1 soil after the sixth S0 application. Thereafter, the SO4 2?‐S concentration decreased significantly. The Thiobacillus spp.count increased consistently with repeated S0 applications. The number of Thiobacillus spp. at the first application of S0 was significantly lower than the count after all other applications. A maximum Thiobacillus spp. count of 1.0 · 108 g?1 soil was observed after the seventh application of S0. The fastest S0 oxidation rate was found after the second application of S0. The population of aerobic heterotrophic sulfur‐oxidizing bacteria increased also with repeated S0 applications, showing a maximum count of 5.0 · 104 g?1 soil after the fourth S0 application. Thereafter, the population declined steadily. Significant relationships between SO4 2?‐S concentration and count of Thiobacillus spp. (R2=0.85, p<0.01) and aerobic heterotrophic sulfur‐oxidizing bacteria (R2=0.63, p<0.01) were found. Based on these results, it may be concluded that repeated S0 applications decrease soil pH, increase Thiobacillus spp. counts, and thus increase extractable SO4 2?‐S concentration in soils. The results further suggest that soils that receive regular S0 applications have a higher Thiobacillus spp. count and thus have conjecturally a higher S0 oxidation potential than soils that have never received S0. This again indicates a priming effect of S0 oxidation by Thiobacillus spp., which needs to be confirmed under field conditions.  相似文献   

10.
To study the influence of potassium (K) fertilizer rate on soil test K values, crop yield, and K-leaching in sandy soils, four long-term fertilizer experiments (0–60–120–180 kg K ha?1 a?1) were initiated in 1988 in northern Germany on farmers fields. Clay content of the plow layer was about 4%, and organic matter between 2% and 5%. Plant available soil K was estimated with the double lactate (DL) method. Small grain cereals (rye and barley) did not respond to K fertilization in the 7-year period even though the soil test value of the K-0 plots decreased from ca. 90 to ca. 30 mg KDL kg?1 within 3 years. This value remained almost constant thereafter. Crop removal (including straw) of 75 kg K ha?1 a?1 was therefore apparently supplied from nonexchangeable K fractions. Compared to the optimum, no K application reduced the yield of potato by up to 21%, and that of white sugar yield up to 10%. Maximum potato yield was obtained by annually applying 60 kg K ha?1 which resulted in a test value of 60 mg KDL kg?1 soil. Maximum potato yield was also obtained at 40 mg KDL kg?1 soil, however, with a single application of 200 kg K ha?1. Similar results were obtained with sugar beet. This indicates that for maximum yield, even for K demanding crops, it is not necessary to maintain KDL values above 40 mg K kg?1 soil throughout the entire crop rotation. Soil test values increased roughly proportional to the K fertilizer level. About 120 kg fertilizer K ha?1 a?1, markedly more than crop K removal, was required to maintain the initial KDL of 90 mg kg?1. The K concentration of the soil solution in the top soil measured after harvest was increased exponentially by K fertilizer level and so was K leaching from the plow layer into the rooted subsoil. The leached quantity increased from 22 kg K ha?1 a?1 in the plot without K application to 42.79 and 133 kg Kha?1 a?1 in plots supplied with 60, 120 and 180 kg K ha?1 a?1 respectively. Soil test values around 100 mg KDL kg?1 on sandy soils, as often found in the plow layer of farmers fields, lead to K leaching below the root zone that may exceed the critical K concentration of 12 mg K T?1 for drinking water.  相似文献   

11.
The effects of several rates of KCl (0–1500 kg/ha) were compared with K2SO4 at the equivalent K rate as 1500 kg/ha KCl on five commercial orchards of kiwifruit (Actinidia deliciosa [A. Chev] C.F. Liang et A.R. Ferguson var. deliciosa cv. Hayward). Leaf breakdown (marginal leaf scorch followed by necrosis and leaf drop) was induced by KCl application at four of the five sites. The symptoms developed at leaf Cl concentrations of 1.5% dry weight and the severity of symptoms increased with leaf Cl concentrations. At another site, a zero K treatment was compared to several rates of KCl (300–1500 kg/ha) and K2SO4 applied at equivalent rates of K in factorial combination with two N fertilizer rates. This site had received KCl and developed severe leaf breakdown in the previous season. Leaf Cl concentrations on the zero K and K2SO4 treatments were higher in this experiment (1.7–2.1% dry weight) than at the other five experimental sites (0.6–1.3%), and at this site mild leaf breakdown symptoms developed on these treatments. Leaf N concentrations were greater, while leaf Cl concentrations and the severity of symptoms were less at the higher N rate. At all of the experimental sites that developed leaf breakdown symptoms, the severity of symptoms increased with the rate of KCl application and were significantly correlated to leaf Cl concentrations but not other leaf nutrient concentrations.  相似文献   

12.
Studies were conducted to determine the efficacy of K salts in alleviating lime‐induced chlorosis. Greenhouse studies using a Gibbon silt loam [fine‐silty, mixed (calcareous), mesic Typic Haplaquoll] and a 1: 1 mixture of Gibbon soil and washed sand were conducted with KCl, KNO3, K2SO4, K2HPO4, or KHCO3 applied at rates of 0, 250, and 500 mg K/kg soil. An FeEDDHA treatment was included for comparison. Similar studies were conducted at two field sites known to produce lime‐induced chlorosis. Potassium salts were applied at 0, 20, and 40 g K/m of row. In the greenhouse, plants treated with KCl, KNO3, and K2SO4 on Gibbon soil were less chlorotic than controls or plants treated with K2HPO4, or KHCO3. No K treatment totally alleviated chlorosis except FeEDDHA. Chlorophyll correlated positively with chlorosis rating. No relationship was found between leaf Fe uptake and chlorosis. Plants grown in soil/sand exhibited no chlorosis and had lower Fe uptake than plants grown in Gibbon soil. Thus chlorosis was not due strictly to low soil‐Fe availability or inadequate Fe uptake. Bicarbonate in the soil solutions of both growth media treated with KCl was lower than controls which may explain the reduced chlorosis associated with this treatment.

One field site showed positive effects of K treatments on chlorosis rating, chlorophyll concentration, and seed yield. No treatment was as effective as FeEDDHA in influencing plant growth or yield. Total leaf Fe concentration was unrelated to leaf chlorophyll concentration. Inorganic cation/anion ratios in the plant were from 4.4–8.4 which could cause net H+ efflux by the plant and alkalinization of plant tissues. One possibility is that H+ efflux solubilizes P in the rhizosphere, which after uptake could immobilize Fe in the plant. Application of KCl, KNO3, and K2SO4 generally lowered HCO3 content of the upper 15 cm of both soils. High bicarbonate could increase rhizosphere P availability and increase immobilization of Fe in the plant.  相似文献   

13.
Abstract

Mungbean [Vigna radiata (L). Wilczek] grown in rainfed calcareous soils suffers with phosphorus (P) deficiency. In view of high cost and low use efficiency of P fertilizer, greenhouse, incubation, and field experiments were carried out for determining P deficiency diagnostic criteria and efficient method of P fertilizer application in mungbean. In a pot culture experiment using a P‐deficient Typic Ustocherpt, maximum increase in grain yield with P was 686% over the control; and fertilizer requirement for near‐maximum (95%) grain yield was 30 mg P kg‐1 soil where fertilizer was mixed with the whole soil volume (broadcast) and 14 mg P kg‐1 where mixed with 1/4th soil volume (band placement). In a field experiment on a P‐deficient Typic Camborthid, however, maximum increase in grain yield was 262% over the control. Band placement resulted in 73% fertilizer saving as P requirement was 66 kg ha‐1 by broadcast and only 18 kg ha‐1 by band placement. Critical P concentration range appears to be 0.27–0.33% in young whole shoots (≤30 cm tall) and 0.25–0.30% in recently matured leaves. In an incubation study using the same Typic Ustochrept, P extracted by the sodium bicarbonate (NaHCO3), the ammonium bicarbonate‐diethlylenetriaminepentaacetic acid (AB)‐DTPA), and the Mehlich 3 soil tests correlated closely with each other, P concentration of whole shoots, and total P uptake by mungbean plants. Critical soil test P levels for pot grown mungbean were NaHCO3,9 mg kg‐1; AB‐DTPA, 7 mg kg‐1; and Mehlich 3, 23 mg dm‐3 soil. The more efficient and economical ‘universal’ soil test, AB‐DTPA, is recommended for P fertility evaluation of calcareous soils.  相似文献   

14.
Abstract

This study was conducted to ascertain the percent of available K, Cl, and SO4‐S recovered by alfalfa (Medicago sativa L. cv. ‘Vernal') herbage when various rates of K as KCl and K2SO4 were topdressed and also to determine where residual K, Cl, and SO4‐S accumulated in the soil profile. An established stand of alfalfa growing on low fertility silt loam soil was topdressed in the spring of each of two harvest years with 0, 448, 896, 1344, and 1792 kg/ha of K as KCl or K2SO4. Four harvests were taken during each harvest year (1972 and 1973). Soil samples were taken during the autumn of 1973 to a depth of 91.4 cm in KCl‐fertilized plots, and to a depth of 76.2 cm in K2SO4‐fertilized and control plots.

Potassium recovery by alfalfa during two harvest years where K as KCl was applied at 448, 896, 1344, and 1792 kg/ha/yr was 56, 33, 20, and 17%, respectively. Recovery of available Cl from those same treatments was 30, 17, 12, and 10%, respectively. Where K as K2SO4 was applied at 448, 896, 1344, and 1792 kg/ha/yr, 55, 35, 27, and 22%, respectively, of available K was recovered. Recovery of available SO4‐S from those same treatments was 16, 9, 7, and 5%, respectively. At the end of two years, a majority of the residual K was in the top 15.2 cm of soil. Residual Cl and SO4‐S were concentrated at a depth of 30.5 to 76.2 cm in the soil profile.  相似文献   

15.
通过田间试验研究了不施肥(CK)、施氮360 kg?hm?2(T1)、施氮720 kg?hm?2(T2)处理下茶园土壤无机氮、p H、各形态氟含量的动态变化和春、夏、秋茶树新梢一芽四叶、一芽五叶氟含量,探讨茶园施氮对土壤和茶树新梢氟含量的影响。结果表明:1)茶园施氮后短期内(20~30 d)土壤水溶态氟含量显著降低,土壤交换态氟和铁锰结合态氟含量降低;长期(45~50 d)土壤水溶态氟含量的降低作用减弱,土壤交换态氟和铁锰结合态的含量增加;在试验结束时(164 d),与CK处理相比,T1处理0~20 cm土壤各形态氟含量降低,T2处理0~20 cm土壤各形态氟含量增加。2)0~20 cm茶园土壤水溶态氟、铁锰结合态氟与NH4+-N分别呈极显著负、正相关(P0.01),20~40 cm土壤水溶态氟、交换态氟与NO3?-N分别呈极显著正、负相关(P0.01)。土壤p H与土壤水溶态氟含量极显著负相关(P0.01),与其他3种形态氟含量相关性不显著。土壤铁锰结合态氟与交换态氟、有机结合态氟呈显著、极显著正相关,但与土壤水溶态氟均无显著相关性。3)春茶前后施氮可以降低春、夏、秋茶树新梢一芽四叶、一芽五叶氟含量,但未达显著水平。T1处理新梢氟含量的降低值为夏茶(25.15~27.95 mg?kg?1)秋茶(21.06~24.31 mg?kg?1)春茶(18.58~21.03 mg?kg?1),T2处理的降低值为秋茶(18.64~22.34 mg?kg?1)夏茶(7.79~14.14 mg?kg?1)春茶(3.52~7.30 mg?kg?1)。春、夏、秋茶树新梢氟含量主要受0~20 cm土壤无机氮和20~40 cm土壤p H的影响。因此推测施氮通过影响茶树根系氟的吸收和氟在叶片中的累积过程调控茶树新梢氟含量,该研究成果为合理利用施氮技术降低茶园土壤和茶树新梢氟含量提供了理论依据。  相似文献   

16.
Annual potassium (K) balances have been calculated over a 40‐year period for five field experiments located on varying parent materials (from loamy sand to clay) in south and central Sweden. Each experiment consisted of a number of K fertilizer regimes and was divided into two crop rotations, mixed arable/livestock (I) and arable only (II). Annual calculations were based on data for K inputs through manure and fertilizer, and outputs in crop removal. Plots receiving no K fertilizer showed negative K balances which ranged from 30 to 65 kg ha?1 year?1 in rotation I, compared with 10–26 kg ha?1 year?1 for rotation II. On sandy loam and clay soils, the K yield of nil K plots (rotation I) increased significantly with time during the experimental period indicating increasing release of K from soil minerals, uptake from deeper soil horizons and/or depletion of exchangeable soil K (Kex). Significant depletion of Kex in the topsoil was only found in the loamy sand indicating a K supply from internal sources in the sandy loam and clay soils. On silty clay and clay soils, a grass/clover ley K concentration of ～2% (dry weight) was maintained during the 40‐year study period on the nil K plots, but on the sandy loam, loam and loamy sand, herbage concentrations were generally less than 2% K.  相似文献   

17.
Background and aims : Most physiological and biochemical studies on salt stress are NaCl‐based. However, other ions (e.g., K+, Ca2+, Mg2+, and SO 4 2 - ) also contribute to salt stress in special circumstances. In this study, salt stress induced by various salts was investigated for a better understanding of salinity. Methods : Arabidopsis thaliana plants were stepwise acclimated to five iso‐osmotic salts as follows: NaCl, KCl, Na2SO4, K2SO4, and CaCl2. Results and Conclusions : Exposure to KCl and K2SO4 led to more severe toxicity symptoms, smaller biomass, and lower level of chlorophyll than exposure to NaCl and Na2SO4, indicating that Arabidopsis plants are more sensitive to potassium salts. The strongly reduced growth was negatively correlated with the accumulation of soluble sugars observed in KCl‐ and K2SO4‐treated plants, suggesting a blockage in the utilization of sugars for growth. We found that exposure to KCl and K2SO4 suppressed or even blocked sucrose degradation, thus leading to strong accumulation of sucrose in shoots, which then probably inhibited photosynthesis via feedback inhibition. Moreover, K+ was more accumulated in shoots than Na+ after corresponding potassium or sodium salt treatments, thus resulting in decreased Ca2+ and Mg2+ concentrations in response to KCl and K2SO4. However, K2SO4 caused more severe toxicity symptoms than iso‐osmotic KCl, even when the K+ level was lower in K2SO4‐treated plants. We found that Na2SO4 and K2SO4 induced strong accumulation of tricarboxylic acid intermediates, especially fumarate and succinate which might induce oxidative stress. Thus, the severe toxicity symptoms found in K2SO4‐treated plants were also attributed to SO 4 2 - in addition to the massive accumulation of K+.  相似文献   

18.
Abstract

Chloride (Cl) toxicity was suspected in corn (Zea mays L.) growing in a poorly‐drained Atlantic Coast Flatwoods soil where Cl toxicity of soybean {Glycine max (L.) Merr.} was a problem. Field and greenhouse research was conducted with rates of applied Cl in an effort to induce Cl toxicity in corn.

‘Trojan 114’ corn was grown in the greenhouse with Cl rates (KCl) of 0, 364, and 728 ug/g and in the field with rates of 0, 85, 170, and 340 kg/ha. Potassium sulfate (K2SO4) treatments were included to supply equivalent amounts of K as that in KCl.

Phytotoxicity of corn did not occur in greenhouse or field experiments with any fertilizer treatment. In the greenhouse Cl concentrations in 26‐day old corn plants grown in a poorly‐drained Flatwoods soil (Leefield sand ‐ arenic Plinthaquic Paleudult) for the 0 and 728 ug Cl/g treatments were 5.0 and 32.7 g/kg in shoots, 1.6 and 14.9 g/kg in ear leaves, and 1.3 and 16.5 g/kg in stalks, respectively. In the field, Cl treatments applied to corn grown in a poorly‐drained Flatwoods soil (Alapaha sand ‐ arenic Plinthic Paleaquults) were not as effective in increasing Cl concentrations in shoots and ear leaves as that for corn grown in a well‐drained soil (Tifton loamy sand ‐ thermic Plinthic Paleudult) apparently because of the greater amount of residual soil Cl in the poorly‐drained soil. Concentrations of Cl in shoots of corn receiving O and 340 kg Cl/ha were 3.8 and 18.0 g Cl/kg, respectively, for corn grown in the well‐drained soil and 16.1 and 18.0 g Cl/kg, respectively, for corn grown in the poorly‐drained soil. Grain yields were not affected by fertilizer treatments on either soil and Cl concentration in grain for corn grown in the Tifton soil was not different among treatments. These data indicate that corn is not very susceptible to high levels of soil Cl.  相似文献   

19.
Abstract

Tea (Camellia sinensis L.) grown in China often suffers from severe seasonal drought in the summer causing drastic effects on productivity. In a field trial, the effect of potassium (K) fertilization on summer tea yields during 1992–1994 was studied and related to the weather conditions of the respective years. Summer tea yields of 1994 (dry year) increased significantly at K2 (300 kg K2O‐ha‐1) compared to the Kl treatment (150 kg K2O ha‐1). In contrast, only marginal effects were observed by increasing K application from Kl to K2 in the years with adequate water availability (1992 and 1993). During the latter maximum tea yields were already achieved with Kl. In addition, a pot experiment was conducted in order to investigate the interaction between the soil water regime and K availability in the soil on tea biomass production. Soil moisture was maintained at 45, 55, 65, 75, and 85% of the field capacity (FC) and K levels were 0 and 500 mg K2Okg‐1. No tea plant survived at the 45% FC level whereas all tea plants survived at or above 75% FC. The survival rate increased substantially in the K treated tea plants under moderate drought stress conditions (55% and 65% FC). The dry matter production was significantly larger with increasing soil moisture and at the high K status in the soil. This observation was most pronounced under water stress conditions. The study indicates that under moisture stress, increased survival, improved dry matter production and yields of tea plants were due to improved K bioavailability following K application. Furthermore, larger amounts of K are required under moisture stress conditions compared to normal water supply.  相似文献   

20.
A pot experiment was conducted to study the contribution of reactive phosphate rocks (RPRs) on the accumulation of Cd and Zn in 10 acid upland soils in Indonesia and shoots of Zea mays plants grown on these soils. Two types of RPR were used at a rate of 0.5 g (kg soil)–1: RPRL containing 4 mg Cd kg–1 and 224 mg Zn kg–1, and RPRH containing 69 mg Cd kg–1 and 745 mg Zn kg–1. Zea mays was harvested at 6 weeks after planting. The application of RPRH significantly increased the concentrations of Cd in the shoots. The application of this RPR also increased the amount of Cd which could be extracted by 0.5 M NH4‐acetate + 0.02 M EDTA pH 4.65 from the soils. More than 90% of the added Cd remained in the soil. As Zn is an essential element and the studied acid upland soils are Zn‐deficient, increased plant growth upon RPR application might be partly attributed to Zn present in the phosphate rock. However, more experiments are needed to confirm this hypothesis. The Cd and Zn concentrations and CEC of the soils were important soil factors influencing the concentrations of Cd and Zn in the shoots of maize plants grown on these soils.  相似文献   

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