Effect of Potassium Supplies on the Nutritional Status of Maize (Zea mays L.)

The effect of soil potassium (K) supplies on the yield and nutritional status of maize and on interactions between the nutrients was examined in a long-term mineral fertilization experiment on maize. The experiment was set up in 1989 in Hungarian Great Plain, Szarvas on chernozem meadow soil calcareous in the deeper layers, with four levels each of nitrogen (N), phosphorus (P) and potassium (K) supplies. The present paper describes the results of K fertilization in the 7–19th years of the experiment, from 1996 to 2008. The ammonium (NH₄)-lactate (AL) potassium oxide (K₂O) content of the ploughed layer ranged from 200 to 550 mg kg^–1 depending on the K fertilization level. No significant yield surpluses were recorded in any of the 13 years in response to the better K supplies ensured by K fertilizer. The results of leaf analysis indicated that the K concentrations representing satisfactory K supplies at a grain yield level of 10–14 t ha^–1 were 2.3–4.3% at the 5–6-leaf stage and 1.5–2.6% at the beginning of tasselling. When the AL-K₂O content of the soil was above 200–320 mg kg^–1, K– calcium (Ca), K–magnesium (Mg) and K–copper (Cu) antagonism was observed in the nutrient concentrations of the maize leaves in most years. The limit values of satisfactory nutrient supplies for maize in the 5–6-leaf stage and at the beginning of tasselling were 0.25–0.60% for Ca, 0.15–0.40% for Mg, and 7–11 mg kg^–1 and 2–11 mg kg^–1, respectively, for Cu. In dry years the iron (Fe) and zinc (Zn) concentrations of maize leaves declined at higher soil K supply levels.     

Predicting potassium fertilizer requirement using exchange isotherm approach in relation to soil characteristics

Determining potassium (K) fertilizer requirement using sorption isotherms is considered more accurate than conventional soil K tests. A total of 59 surface soil samples were used to establish K exchange isotherm. To evaluate K requirement sorption test, a glasshouse experiment using perennial ryegrass (Lolium perenne, cv. Roper) was carried out on 10 soil samples. The experiment was laid out as a completely randomized design with four replications and four K levels (K₀, K₂₀, K₄₀, K₈₀). Concentrations of K in solution established by adding K in the pots estimated from the sorption curve ranged from 20 to 80 mg K l^?1 including check treatment (no K). Dry matter yield of ryegrass in most soils approached maximum as adjusted K levels were increased to 20 mg K l^?1. The amounts of K required to bring the soils to 20 mg l^?1 in soil solution varied among soils and ranged from 99 to 399 mg kg^?1, on average 205 mg kg^?1 soil. It was found that a useful regression model for the prediction of standard K requirement (K₂₀) included the combination of plant available K extracted by NH₄OAc (Av-K) and clay content: K₂₀ = ?41 ? 0.63 Av-K + 9.0 Clay (R² = 0.61, p < 0.001, n = 59).     

GREENHOUSE GAS EMISSIONS FROM AN ALKALINE SALINE SOIL CULTIVATED WITH MAIZE (ZEA MAYS L.) AND AMENDED WITH ANAEROBICALLY DIGESTED COW MANURE: A GREENHOUSE EXPERIMENT

Sludge derived from cow manure anaerobically digested to produce biogas (methane; CH₄) was applied to maize (Zea mays L.) cultivated in a nutrient-low, alkaline, saline soil with electrolytic conductivity 9.4 dS m^?1 and pH 9.3. Carbon dioxide (CO₂) emission increased 3.1 times when sludge was applied to soil, 1.6 times when cultivated with maize and 3.5 times in sludge-amended maize cultivated soil compared to the unamended uncultivated soil (1.51 mg C kg^?1 soil day^?1). Nitrous oxide (N₂O) emission from unamended soil was -0.0004 μg nitrogen (N) kg^?1 soil day^?1 and similar from soil cultivated with maize (0.27 μg N kg^?1 soil day^?1). Application of sludge increased the N₂O emission to 4.59 μg N kg^?1 soil day^?1, but cultivating this soil reduced it to 2.42 μg N kg^?1 soil day^?1. It was found that application of anaerobic digested cow manure stimulated maize development in an alkaline saline soil and increased emissions of CO₂ and N₂O.     

Potassium fertilization on sandy soils in relation to soil test,crop yield and K-leaching

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 K_DL 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 K_DL kg^?1 soil. Maximum potato yield was also obtained at 40 mg K_DL 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 K_DL 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 K_DL 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 K_DL 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.     

Evaluation of Extractants and Quantity–Intensity Relationship for Estimation of Available Potassium in Some Calcareous Soils of Western Iran

Accurate estimation of the available potassium (K⁺) supplied by calcareous soils in arid and semi‐arid regions is becoming more important. Exchangeable K⁺, determined by ammonium acetate (NH₄OAc), might not be the best predictor of the soil K⁺ available to crops in soils containing micaceous minerals. The effectiveness of different extraction methods for the prediction of K‐supplying capacities and quantity–intensity relationships was studied in 10 calcareous soils in western Iran. Total K⁺ uptake by wheat grown in the greenhouse was used to measure plant‐available soil K⁺. The following methods extracted increasingly higher average amounts of soil K⁺: 0.025 M H₂SO₄ (45 mg K⁺ kg^?1), 1 M NaCl (92 mg K⁺ kg^?1), 0.01 M CaCl₂ (104 mg K⁺ kg^?1), 0.1 M BaCl₂ (126 mg K⁺ kg^?1), and 1 M NH₄OAc (312 mg K⁺ kg^?1). Potassium extracted by 0.01 M CaCl₂, 1 M NaCl, 0.1 M BaCl₂, and 0.025 M H₂SO₄ showed higher correlation with K⁺ uptake by the crop (P < 0.01) than did NH₄OAc (P < 0.05), which is used to extract K⁺ in the soils of the studied area. There were significant correlations among exchangeable K⁺ adsorbed on the planar surfaces of soils (labile K⁺) and K⁺ plant uptake and K⁺ extracted by all extractants. It would appear that both 0.01 M CaCl₂ and 1 M NaCl extractants and labile K⁺ may provide the most useful prediction of K⁺ uptake by plants in these calcareous soils containing micaceous minerals.     

Potassium Status in Maize Rhizosphere of Smectitic Soils

This study has been taken up to generate information on potassium status in maize rhizosphere soils differing in their clay content at different levels of added potassium. Soils with larger amounts of clay showed greater amounts of water soluble and ammonium acetate extractable K (NH₄OAc K) in both the rhizosphere as well as non-rhizosphere. In the absence of added K (control), non-rhizosphere samples showed higher water soluble and NH₄OAc K ranging from 8.0 to 28.9 mg kg^?1 and from 132.5 to 294.0 mg kg^?1, respectively compared to rhizosphere samples where water soluble K varied between 6.0 and 26.5 mg kg^?1 and NH₄OAc K from 125.0 to 262.5 mg kg^?1. The difference in K content between rhizosphere and non-rhizosphere which could have been resulted from plant K uptake was significantly related with clay content (r = 0.98**) in control whereas at 150 mg kg^?1 K addition this relationship was found to be non significant (r = 0.64^NS). Electro ultra filtration (EUF) fractions also showed similar differences in K contents in soil between rhizosphere and non-rhizosphere.     

Micronutrient availability in soils of Northwest Bosnia and Herzegovina in relation to silage maize production

Maize (Zea mays L.) is the most widely grown crop in Bosnia and Herzegovina especially in Northwest part of the country. Considering that, the maize is extremely sensitive to micronutrient deficiency the main aim of this study was to asses: (1) micronutrient availability in soil, (2) micronutrient status in silage maize; and (3) the relationship between micronutrient soil availability and maize plant concentration. Soil samples for micronutrient availability (n?=?112) were collected from 28 farms in 7 municipalities. Plant available micro- and macro- nutrients in soil were extracted using Mehlich-3, except plant available Se was extracted using 0.1M KH₂PO₄. Result showed that on average there was no significant difference between different soil types regarding their potential in plant available nutrients. P deficiency was present both, in soil and plants in whole region. Soil extractable P was ranging from 0.003–0.13?g?kg^?1 and total plant P was ranging from 0.79–4.95?g?kg^?1. Zinc deficiency was observed in two locations both in soil (0.71?mg?kg^?1; 0.79?mg?kg^?1) and plant (11.5?mg?kg^?1; 15.8?mg?kg^?1). Potential Se soil deficiency was observed on some locations, while Se plant status is not high enough to meet daily requirements of farm animals. Extractable soil nutrients could be used as relatively good predictor of potential soil and plant deficiencies, but soil nutrient interactions and climate conditions are highly effecting the plant uptake potential.     

A study on the improvement iron nutrition of peanut intercropping with maize on nitrogen fixation at early stages of growth of peanut on a calcareous soil

Abstract

A glasshouse study employing a split-root technique was conducted to investigate the influence of intercropping with maize (Zea mays L.) in a calcareous soil on N₂ fixation by peanut (Arachis hypogaea L.) at early stages of growth. In this intercropping system, competitive interactions between maize and peanut for N and improvement of Fe uptake were likely to be important factors affecting N₂ fixation of peanut. The experiment was comprised of three treatments which included treatment I: peanut monocropping; treatment II: maize/peanut intercropping (the major and the minor compartments with low N, 50 mg kg^?1); treatment III: maize/peanut intercropping (the major compartment with low N, 50 mg kg^?1 and the minor compartment with high, N 200 mg kg^?1). The minor compartment of treatment III was fertilized with 200 mg kg^?1 N for reducing or eliminating the competition of N coming from intercropping maize. Intercropping with maize corrected Fe chlorosis of peanut by significantly increasing plant Fe concentration and uptake. Compared with the monocropping treatment, iron uptake increased from intercropping treatment II and III by 22 and 24% per plant, 30 and 29% shoots, 38 and 60% nodules. Iron uptake by the root nodules was especially enhanced in the intercropping system. In contrast, intercropping with maize had little effect on NO₃ ^?1-N concentrations in the soil rhizosphere of peanut or on N concentrations and uptake by peanut compared with plants in monoculture. The results indicate that the improvement in Fe nutrition was an important factor promoting N₂ fixation by peanut in the intercropping system at the flowering stage of peanut growth, and that competition for N by intercropped maize had little effect on N₂ fixation by peanut under the experimental conditions.     

Nitrogen,Phosphorus and Potassium Interactions in Upland Rice

Upland rice is an important crop in South America, including Brazil. Nutrient interactions are important in determining crop yields. A greenhouse experiment was conducted to evaluate interaction among nitrogen (N), phosphorus (P), and potassium (K) in upland rice production. The treatments applied to upland rice grown on an Oxisol were three levels of N (N₀, N₁₅₀ and N₃₀₀ mg kg^?1), three levels of P (P₀, P₁₀₀ and P₂₀₀ mg kg^?1) and three levels of K (K₀, K₁₀₀ and K₂₀₀ mg kg^?1). These treatments were tested in a 3 × 3 × 3 factorial arrangement. Grain yield, shoot dry weight, plant height, root dry weight, maximum root length, panicle number, 1000-grain weight, and grain harvest index were significantly influenced by N, P, and K treatments. The treatment that did not receive P fertilization did not produce panicle or grain. Hence, P was most yield-limiting nutrient compared to two other nutrients. At the N₀P₀K₀ treatment, rice did not produce grains, indicating severe deficiency of these nutrients in Brazilian Oxisols. Maximum grain yield was obtained with the N₃₀₀P₂₀₀K₂₀₀ treatment. Grain yield had significant positive association with plant height, shoot dry weight, root dry weight, maximum root length, 1000-grain weight, panicle number, and grain harvest index. Among these growth and yield components, shoot dry weight had the highest positive association with grain yield and root length minimum positive association with grain yield. Hence, adopting adequate soil and crop management practices can improve growth and yield components and increase grain yield of upland rice.     

Recovery of 15N Labelled Urea as Affected by Fixation of Ammonium by Clay Minerals

A greenhouse experiment was conducted with Lolium perenne to determine whether ammonium (NH₄⁺-N) fixation by clay minerals can increase the recovery of nitrogen following application of ¹⁵N labelled urea. A silty loam subsoil, B_t horizon from an Alfisol derived from loess, pH (CaCl₂) 7.9, was chosen for the experiment. The NH₄⁺-N fixation capacity was altered by varying the distribution of potassium (K) in the upper and lower soil layer. In the K₀ treatment (control), the upper soil layer fertilized with urea was not supplied with K, whereas the lower soil layer was fertilized with 300 mg K kg^?1 soil. In the K₁^?, K₂^? and K₃ treatment the upper soil was supplied with 100-, 200- and 300 mg K kg^?1 soil, respectively. The soil in the lower layer of the K₃ treatment was not supplied with K. The recovery of ¹⁵N from applied urea (¹⁵N uptake of Lolium perenne plus residual soil ¹⁵N_t) was 86.1% in the K₀ treatment and 75.2%, 69.1% and 69.6% in K_1-, K_2- and K₃ treatments, respectively, showing that ¹⁵N losses were smallest in the K₀ treatment. Two weeks after applying ¹⁵N labelled urea the amounts of nonexchangeable ¹⁵NH₄⁺-N in the upper soil layer were significantly higher in the K₀ treatment than in the treatments with K application. Apparently, NH₄⁺-N fixation by clay minerals can reduce NH₃ volatilization after urea fertilization, if the amount of exchangeable K is low.     

Potassium Quantity–Intensity Parameters and Their Correlation with Bean Plant Indices in Some Calcareous Soils

Plant availability of potassium (K) in soils is controlled by dynamic interactions among its different pools. Potassium quantity–intensity (Q/I) parameters were determined to relate them to bean plant indices in a pot experiment. The results showed that the activity ratio at equilibrium (AR^k) ranged from 0.015 to 0.358 (mmol L^?1)^0.50, the potential buffering capacity (PBC) ranged from 7.54 to 26.32 mmol kg^?1/(mmol L^?1)^0.50, the labile K (Δk°) ranged from 9.1 to 112.2 mg kg^?1, and the K adsorbed at specific sites (Kx) ranged from 6.51 to 69.69 mg kg^?1. The results of pot experiment showed that some K Q/I parameters were significantly correlated with some plant indices. Also, the correlation study showed that readily exchangeable K was significantly correlated with K Q/I parameters except K_x. The results of this research show that the K Q/I method can be used for estimating of soil K availability for bean.     

Potassium Dynamics in Inceptisols as Influenced by Graded Levels of Potash for Banana: I. Potassium Fractions

Knowledge of forms of potassium (K) in soil is of great importance for formulating sound fertilizer recommendation to banana. Field experiments were conducted to study the effect of graded levels of potash application on forms of potassium at juvenile, grand growth, shooting, and harvest stages of banana on Vertic Haplustept soil. The negative balance of soil-available K was observed in the treatments of 0, 100, and 200 g K₂O plant^?1. However, at 300-g K₂O plant^?1 level, the balance was a mere –11 kg ha^?1, and positive balance was observed in the treatments of 400 and 500 g K₂O plant^?1. Significant positive correlation among different forms of K indicated the interdependency and dynamic equilibrium between K forms. Application of K₂O above the level of 300 g plant^?1 for banana resulted in the build-up of potassium fractions in soil.     

Response of tomato to polyhalite as a multi-nutrient fertilizer in southeast Brazil

Abstract

Limited information on the agronomic performance of polyhalite (K₂SO₄.MgSO₄.2CaSO₄.2H₂O) motivated us to establish two field trials in Sao Paulo, Brazil. The objective was to evaluate the comparative responses of tomato to muriate of potash (MOP), sulfate of potash, potassium magnesium sulfate, and polyhalite at different graded doses of potassium (K) application supplying varied amount of secondary nutrients. Under very low soil K conditions, polyhalite resulted in significantly higher marketable fruit yield, and higher foliar and fruit K and sulfur (S) concentrations than other K sources. This was not the case under medium soil K levels, that is, 101?mg?kg^?1. Likewise, polyhalite enhanced postharvest residual soil calcium (Ca), magnesium (Mg), and S than other evaluated sources. Depending on soil nutrient status and the cost of polyhalite, tomato farmers of Brazil could consider polyhalite as an option to meet crop K and secondary nutrient requirements.     

Potassium fertilization and soil diagnostic criteria for forage corn (Zea mays L.) production contributing to lower potassium input in regional fertilizer recommendation

Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha^?1 for ‘Cecilia’ and from 123 to 411 kg K ha^?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg^?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha^?1 was estimated to be approximately 200 kg K ha^?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg^?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg^?1, inorganic K fertilizer application at 83 kg K ha^?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg^?1, inorganic K fertilizer is applied at 83 kg K ha^?1 (100 kg ha^?1 as potassium oxide (K₂O) equivalent); at an Ex-K content of 0.15–0.30 g kg^?1, the application rate is reduced to 33 kg K ha^?1 (40 kg K₂O ha^?1); at an Ex-K content of ≥ 0.30 g kg^?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.     

Wheat response to combined application of nitrogen and phosphorus in a saline sandy loam soil

Fertilization with nitrogen (N) or phosphorus (P) can improve plant growth in saline soils. This study was undertaken to determine wheat (Triticum aestivum L; cv Krichauff) response to the combined application of N and P fertilizers in the sandy loam under saline conditions. Salinity was induced using sodium (Na⁺) and calcium (Ca²⁺) salts to achieve four levels of electrical conductivity in the extract of the saturated soil paste (EC_e), 2.2, 6.7, 9.2 and 11.8?dS?m^?1, while maintaining a low sodium adsorption ratio (SAR; ≤1). Nitrogen was applied as Ca(NO₃)₂?·?4H₂O at 50 (N50), 100 (N100) and 200 (N200)?mg?N?kg^?1 soil. Phosphorus was applied at 0 (P0), 30 (P30) and 60 (P60)?mg?kg^?1?soil in the form of KH₂PO₄. Results showed that increasing soil salinity had no effect on shoot N or P concentrations, but increased shoot Na⁺ and chlorine ion (Cl^?) concentrations and reduced dry weights of shoot and root in all treatments of N and P. At each salinity and P level, increasing application of N reduced dry weight of shoot. At each salinity and N level P fertilization increased dry weights of shoot and root and shoot P concentration. Addition of greater than N50 contributed to the soil salinity limiting plant growth, but increasing P addition up to 60?mg?P?kg^?1 soil reduced Cl^? absorption and enhanced the plant salt tolerance and thus plant growth. The positive effect of the combined addition of N and P on wheat growth in the saline sandy loam is noticeable, but only to a certain level of soil salinity beyond which salinity effect is dominant.     

Zinc Requirement of Maize Hybrids and Indigenous Varieties on Udic Haplustalf

ABSTRACT

A pot study was conducted on Gujranwala series (Udic Haplustalf) to compare zinc (Zn) requirement of maize hybrids (FHY- 456, FHY- 396, and FHY- 421) and indigenous varieties (EV-1089, Golden, and Soneri). Uniform rates of nitrogen:phosphorus:potassium (N:P:K) and four rates of Zn were applied in triplicate according to CRD. There was a significant (P < 0.05) main and interactive effect of maize genotypes and zinc application on shoot growth and Zn uptake. The three maize varieties uniformly produced maximum shoot dry weight at 3 mg Zn kg^?1 soil. The maize hybrids produced maximum shoot dry weight at 9 mg Zn applied kg^?1 soil. A 6.3 mg Zn kg^?1 plant tissue was optimum for FHY-421 (hybrid) and 9.5 mg Zn kg^?1 plant tissue was optimum for Soneri (variety). Hence, more pronounced response in maize hybrids than indigenous varieties require higher rates of Zn application. However, further verification of the results is warranted under field conditions.     

Metal uptake in maize, willows and poplars on impoldered and freshwater tidal marshes in the Scheldt estuary

Foliar Cd and Zn concentrations in Salix, Populus and Zea mays grown on freshwater tidal marshes were assessed. Soil metal concentrations were elevated, averaging 9.7 mg Cd kg^?1 dry soil, 1100 mg Zn kg^?1 dry soil and 152 mg Cr kg^?1 dry soil. Cd (1.1–13.7 mg kg^?1) and Zn (192–1140 mg kg^?1) concentrations in willows and poplars were markedly higher than in maize on impoldered tidal marshes (0.8–4.8 mg Cd kg^?1 and 155–255 mg Zn kg^?1). Foliar samples of maize were collected on 90 plots on alluvial and sediment‐derived soils with variable degree of soil pollution. For soil Cd concentrations exceeding 7 mg Cd kg^?1 dry soil, there was a 50% probability that maize leaf concentrations exceeded public health standards for animal fodder. It was shown that analysis of foliar samples of maize taken in August can be used to predict foliar metal concentrations at harvest. These findings can therefore contribute to anticipating potential hazards arising from maize cultivation on soils with elevated metal contents.     

Silicon and Potassium Nutrition Enhances Salt Adaptation Capability of Sunflower by Improving Plant Water Status and Membrane Stability

The relationships between salinity and mineral nutrition are extremely complex and may change depending on many factors in soil-plant system. We investigated the contribution of silicon (Si at 50 mg kg^?1 soil) and potassium (K at 40 and 60 mg K₂O kg^?1 soil) to improve salt tolerance in sunflower grown with 100 mM sodium chloride (NaCl). The experimental design was factorial based on a completely randomized design with five replications. Added NaCl increased sodium ion (Na⁺) accumulation by 966 percent in shoots and 1200 percent in roots but reduced shoot potassium ion (K⁺) concentration by 49 percent, root K⁺ 51 percent, and shoot K⁺/Na⁺ ratio 95 percent. However, Si and K application effectively reduced Na⁺ accumulation and increased K⁺ concentration and K⁺:Na⁺ ratio, with a significant improvement in plant growth and yield. Among all treatments, greater alleviative effects of Si and K were observed for 50 mg Si + 60 mg K₂O kg^?1 soil, which decreased shoot Na⁺ concentration by 67 percent, root Na⁺ 18 percent, and shoot Na⁺/root Na⁺ ratio 60 percent and increased shoot K⁺ by 198 percent, shoot K⁺/Na⁺ ratio 812 percent, membrane stability index (MSI) 35 percent, relative water content (RWC) 26 percent, and seed weight head^?1 86 percent compared to salt-stressed plants without supplemental Si and K. Most of the plant growth parameters were negatively correlated with Na⁺ accumulation but positively correlated with K⁺ and K⁺/Na⁺ ratio. This study suggests that Si and K mediated reduction in Na⁺ accumulation, and increase in K⁺ concentration, K⁺/Na⁺ ratio, RWC, and MSI are the main factors contributing to improved adaptation capability of sunflower to NaCl stress.     

POTATO TUBER YIELD AND QUALITY AS AFFECTED BY RATES AND SOURCES OF POTASSIUM FERTILIZER

Among the major nutrients, potassium (K) not only improves yields but also improves quality parameters. Field experiments were conducted to assess the comparative effect of sources and rates of K fertilizer on potato yield and quality on a sandy loam soil. Graded doses of potassium, i.e., 0, 150 and 225 kg ha^?1 K₂O from sulfate and muriate of potash were applied in triplicate. Recommended dose of nitrogen (N) and phosphorus (P) applied uniformly. Significant increase in tuber yield was observed with 150 kg ha^?1 K₂O from both the sources over control. Increase in tuber yield with 225 kg ha^?1 K₂O was statistically non significant compared to 150 kg ha^?1. The dry matter and specific gravity were more affected with sulfate of potash (SOP) than muriate of potash (MOP). The quality parameters like dry matter, specific gravity, starch contents, vitamin C, chips color and taste were improved with K application.     

Phytotoxic Effect of the Uranium on the Growing Up and Development the Plant of Corn

The aim of this article is the determination of uranium accumulation in plants tissue in shoots and roots of corn—maize (Zea mays), grown on two types of soils, pseudogley and chernozem, together with its phytotoxic effect on the plant growth and development. The soils was contaminated with different rates (10 to 1,000 mg U(VI) kg^?1) of uranyl nitrate (UO₂(NO₃)₂·6H₂O). Vegetative tests performed with maize indicated uranium phytotoxic effect on plant height, yield, and germination of seeds. This effect was stronger on the plants grown on pseudogley in comparison with those grown on chernozem. Soil properties determined the tolerance and accumulation of U in plants. A linear dependence between the content of uranium in soil and in plants tissue, including maximal content of 1,000 mg U?kg^?1, indicates that maize could be used for phytoremediation of uranium-contaminated soils.