Showing papers in "Journal of Plant Nutrition in 2001"

Nutrient interactions in crop plants

Abstract: Balanced supply of of essential nutrients is one of the most important factors in increasing crop yields. The objective of this review is to discuss interactions among major and minor nutrients in crop plants. In crop plants, the nutrient interactions are generaly measured in terms of growth response and change in concentration of nutrients. Upon addition of two nutrients, a increase in crop yield that is more than adding only one, the interaction is positive (synergistic). Similarly, if adding the two nutrients together produced less yield as compared to individual ones, the interactions is negative (antagonistic).When there is no change, there is no interaction. All the three interactions among essential plant nutrients have been reported. However, most interactions are complex. A nutrient interacting simultaneously with more than one nutrients. This may induced deficiencies, toxicities, modified growth responses, and/or modified nutrient composition. Better understanding of nutrient interactions may be...

Contribution of proline and inorganic solutes to osmotic adjustment in cotton under salt stress

Abstract: Physiological responses to salt stress were investigated in two cotton (Gossypium hirsutum L.) cultivars (Pora and Guazuncho) grown hydroponically under various concentrations of NaCl. Dry matter partitioning, plant water relations, mineral composition and proline content were studied. Proline and inorganic solutes were measured to determine their relative contribution to osmotic adjustment. Both leaf water potential (Ψw) and osmotic potential (Ψs)decreased in response to NaCl levels. Although Ψwand Ψs decreased during salt stress, pressure potential Ψp remained between 0.5 to 0.7 MPa in control and all NaCl treatments, even under 200 mol m−3 NaCl. Increased NaCl levels resulted in a significant decrease in root, shoot and leaf growth biomass. Root / shoot ratio increased in response to salt stress. The responses of both cultivars to NaCl stress were similar. Increasing salinity levels increased plant Na+ and Cl−. Potassium level remained stable in the leaves and decreased in the roots with increasing sal...

Phosphite (phosphorous acid): its relevance in the environment and agriculture and influence on plant phosphate starvation response

Abstract: Phosphites (H2PO3 −; Phi) are alkali metal salts of phosphorous acid [HPO(OH)2] that are being widely marketed either as an agricultural fungicide or as a superior source of plant phosphorus (P) nutrition. Published research conclusively indicates that Phi functions as an effective control agent for a number of crop diseases caused by various species of pathogenic pseudo fungi belonging to the genus Phytophthora. However, evidence that Phi can be directly used by plants as a sole source of nutritional P is lacking. When Phi is administered in such as way as to allow it to come into contact with bacteria, either associated with plant root systems or in the soil, then the oxidation of Phi to phosphate (HPO4 2−; Pi) may take place. By this indirect method Phi could thus become available to the plant as a P nutrient. The rates at which this occurs are slow, taking months or as much as a year, depending on the soil type. Phi is not without direct effects on plants itself, as Phi concentrations comparable to th...

ENHANCEMENT OF GROWTH AND NORMAL GROWTH PARAMETERS BY FOLIAR APPLICATION OF POTASSIUM AND PHOSPHORUS IN TOMATO CULTIVARS GROWN AT HIGH (NaCl) SALINITY

Abstract: Three tomato (Lycopersicon esculentum) cvs., Rio Grande, Monika F1, and Marylin F1, were grown hydroponically in a controlled temperature (CT) room for 6 weeks to investigate the effectiveness of foliar application of supplementary potassium (K) and phosphorus (P) to the leaves of plants grown at high NaCl concentration (60 mM). Supplementary 5 mM K and P as KH2PO4 was supplied via leaves to the plants grown at high NaCl (60 mM) twice a week for 4 weeks. The plants grown at high NaCl produced less dry matter and chlorophyll than those at normal nutrient solution for all three cultivars. Membrane permeability increased with high NaCl application and these increases in membrane permeability were decreased by supplementary K and P. Daily water use by plant was decreased with high NaCl application and increased with supplementary P and K. Foliar application of supplementary K and P resulted in increases in dry matter and chlorophyll concentrations for all three cultvars. These increases were greater in Monika...

Nitrogen fertilization optimization algorithm based on in-season estimates of yield and plant nitrogen uptake

Abstract: Current methods of determining nitrogen (N) fertilization rates in winter wheat (Triticum aestivum L.) are based on farmer projected yield goals and fixed N removal rates per unit of grain produced. This work reports on an alternative method of determining fertilizer N rates using estimates of early-season plant N uptake and potential yield determined from in-season spectral measurements collected between January and April. Reflectance measurements under daytime lighting in the red and near infrared regions of the spectra were used to compute the normalized difference vegetation index (NDVI). Using a modified daytime lighting reflectance sensor, early-season plant N uptake between Feekes physiological growth stages 4 (leaf sheaths lengthen) through 6 (first node of stem visible) was found to be highly correlated with NDVI. Further analyses showed that dividing the NDVI sensor measurements between Feekes growth stages 4 and 6, by the days from planting to sensing date was highly correlated with final grain...

Calibration of soil and plant silicon analysis for rice production

Abstract: Calibration of field crop response to nutrient availability is the bases for making a fertilizer recommendation from soil and tissue analyses. The purpose of this study was to evaluate and summarize results from a series of experiments on silicon (Si) fertilization of rice in the Everglades Agriculture Area. Twenty-eight rice field experiments were conducted from 1992 through 1996. The experiments consisted of 2 to 5 rates of calcium silicate applied to soils (Histosols) of varying Si soil-test values. Soil samples were taken before planting and analyzed for acetic acid (0.5 mol L−1) extractable Si. Straw samples were collected at harvest and analyzed for total Si. Grain yield was determined. The “critical” levels for Si in the soil (point below which response to Si fertilizer is expected) calculated by the Cate & Nelson procedure was 19 mg Si L−1 soil. The amount of silicon to correct Si deficiency in the soil and to obtain optimum rice yield was 1500, 1120 and 0 kg ha−1 for low (<6 mg L−1), medium (6 to...

Nickel toxicity induces oxidative damage in zea mays roots

Abstract: Seven day-old maize (Zea mays cv. LG 23/01) plants were treated for five days with 250 μM NiCl2. The relationship between nickel (Ni) toxicity and oxidative reactions were studied in roots during metal accumulation. Membrane lipid peroxidation enhanced only 6 h after metal treatment before roots revealed a decrease in growth. The activities of superoxide dismutase (SOD), EC 1.15.1.1, guaiacol peroxidase (GPX), EC 1.11.1.7, were unaffected by Ni stress. However, catalase (CAT), EC 1.11.1.6, activity was increased from 24 h after metal treatment. In the ascorbate gluthatione cycle, only two enzymes, the ascorbate peroxidase (APX), EC 1.11.1.11, and monodehydroascorbate reductase (MDHAR), EC 1.6.5.4, were stimulated, while the activities of dehydroascorbate reductase (DHAR), EC 1.8.5.1, and glutathione reductase (GR), EC 1.6.4.2, remained around the control values. The results suggest that oxidative disorder is part of the overall expression of Ni toxicity in roots of Zea mays and that enhanced lipid peroxid...

Inter-relationships of applied nitrogen, spad, and yield of leafy and non-leafy maize genotypes

Abstract: The SPAD chlorophyll meter was found to be a reliable, quick, and non-destructive tool used for directly measuring leaf chlorophyll and indirectly assessing the proportional parameter of leaf, and by extension, plant nitrogen (N) status. The meter has been used successfully to assess leaf N in conventional maize crops, but it has not been used with new maize (Zea mays L.) genotypes containing leafy (L) and reduced stature (RS) traits. SPAD meter readings were collected on the uppermost fully developed leaves (before silking) and on the ear leaf (after silking) of field grown maize genotypes with and without the L and RS traits. The experiment was conducted during 1996 and 1997 at two sites in Eastern Canada (Ottawa and Montreal). At each site in each year, a split plot arrangement of two treatment factors was used in a randomized complete block design with four blocks. The main plot treatments were levels of N (0, 85, 170, and 255 kg ha−1), with six maize genotypes as subplot treatments. The hybrids inclu...

Salinity and ammonium/nitrate interactions on tomato plant development, nutrition, and metabolites

Abstract: The interactions between NaCl and different NO3 −NH4 + ratios were investigated. Tomato plants (Lycopersicon esculentum Mill.) were grown in a greenhouse, in 120L capacity containers filled with continuously aerated Hoagland nutrient solution. Treatments were added to observe the combined effect of two NaCl levels (30 and 60 mM) and three millimolar ratios of nitrate: ammonium (14:0, 12:2, 10:4) on growth, nutrition, and contents of chlorophyll and sugars. Saline treatments decreased growth, which was partly restored by NH4 + treatment. The leaf mineral composition showed a marked effect of nitrogen (N) source, while salinity only affected NO3 − concentration. Changing the NO3 −:NH4 + ratio from 14:0 to 12:2 and 10:4 produced progressive increases in the concentrations of iron (Fe), chlorophyll, and reducing sugars in leaves. Therefore, the deleterious effect of salinity on biomass production can be minimized by the use of nutrient solutions containing higher NH4 + concentrations, since this seemed to be ...

Effects of zinc fertilization on grain yield and shoot concentrations of zinc, boron, and phosphorus of 25 wheat cultivars grown on a zinc-deficient and boron-toxic soil

Abstract: Field experiments were carried out to study the grain yield, shoot concentrations of zinc (Zn), boron (B) and phosphorus (P), and tolerance to Zn deficiency of 21 bread wheat (Triticum aestivum) and four durum wheat (Triticum durum) cultivars grown in a B-toxic and Zn-deficient calcareous soil in Central Anatolia with (+Zn = 23 kg Zn ha−1) and without Zn fertilization in 1993–1994 and 1994–1995 cropping seasons. Tolerance to Zn deficiency (Zn efficiency ratio) was measured by considering the ratio of grain yield under Zn deficiency to that with Zn fertilization. Zinc fertilization significantly increased grain yield of all cultivars in both years. On average, increases in grain yield of 25 wheat cultivars by Zn fertilization were 37% in the first and 40% in the second year. When results of the 2 cropping seasons were averaged, Zn efficiency ratios of the cultivars ranged from 40% to 84%, with an average of 62%. Despite large genotypic variation in Zn efficiency, shoot Zn concentrations under Zn-deficient ...

EFFECTS OF SUPPLEMENTARY POTASSIUM AND PHOSPHORUS ON PHYSIOLOGICAL DEVELOPMENT AND MINERAL NUTRITION OF CUCUMBER AND PEPPER CULTIVARS GROWN AT HIGH SALINITY (NaCl)

Abstract: Two cucumber (Cucumis sativus) cultivars, Seraset F1 and Rabina F1, and two pepper (Capsicum annuum) cultivars, California Wonder and Charliston 52, were grown hydroponically for six weeks to investigate the effectiveness of supplementary potassium (K) and phosphorus (P) applied to the root zone of plants grown at high (60 mM) NaCl concentration. Treatments used in this experiment were (i) control: nutrient solution alone, (ii) high salt: nutrient solution plus 60 mM NaCl, and (iii) high salt with supplementary P and K: nutrient solution plus 60 mM NaCl, 1 mM KH2PO4, and 2 mM K2SO4. Supplementary 1 mM KH2PO4 and 2 mM K2SO4 was added to nutrient solution for four weeks. Plants grown at high salt produced less dry matter and chlorophyll than those in normal nutrient solution for both cucumber and pepper cultivars. Reductions in both dry matter and chlorophyll concentrations were greater for pepper than cucumber. Supplementary K and P restored dry matter and chlorophyll concentrations for both species to lev...

Relationships between extractable chlorophyll and spad values in muskmelon leaves

Abstract: Chlorophyll content of muskmelon is usually determined by destructively sampling plant leaves. However, a hand-held SPAD-502 Chlorophyll Meter provides rapid and nondestructive measurements of leaf chlorophyll content. This study aims to determine the relationships between extractable chlorophyll and SPAD values in muskmelon leaves. SPAD readings were significantly related to extracted chlorophyll of muskmelon leaves both on a fresh weight and leaf area basis. Quadratic equations best described their relationships. At 10 days after nitrogen (N) fertilization, the r2 values for chlorophyll a, b, and total chlorophyll on a fresh weight basis were 0.84, 0.86, and 0.85, respectively, while on a leaf area basis, r2 values were 0.92, 0.95, and 0.94, respectively. At 17 days after fertilization, the r2 values for chlorophyll a, b, and total chlorophyll on a fresh weight basis were 0.57, 0.49, and 0.56, respectively, while on a leaf area basis, r2 were 0.72, 0.67, and 0.71, respectively. Therefore, the SPAD-502 C...

Effects of silicon on growth and mineral composition of barley grown under toxic levels of aluminum

Abstract: Growth chamber studies were conducted to investigate the effects of silicon (Si) on plant growth and nutrient uptake in barley (Hordeum vulgare L.) grown hydroponically under toxic levels of aluminum (Al). Treatments were 0, 100, or 150 μmol L−1 Al (as AlCl3), and 0 or 1.0 mmol L−1 Si (as silicic acid) in Experiment A; and 0, 50, or 75 μmol L−1 Al (as AlCl3) and 0.5 or 1.0 mmol L−1 Si (as silicic acid) in Experiment B. The Al and Si treatments were arranged factorically in a randomized, complete block design with three replicates. Aluminum added significantly (P < 0.05) increased plasma membrane permeability, which was not alleviated by added Si. The addition of Si significantly (P < 0.05) reduced root length, dry weight, shoot nitrogen (N) and phosphorus (P) concentration, root N and potassium (K) concentration, and increased root P concentration of barley plants exposed to 75 μmol L−1 Al and above. Nutrient uptake was significantly inhibited when plants were grown under 75 μmol L−1 Al and above, regardl...

Germination, sodium, and potassium concentrations of barley seeds as influenced by salinity

Abstract: Seed germination is a major factor limiting the establishment of plants under saline conditions. Six barley (Hordeum vulgare L.) cultivars were screened for salt tolerance (using NaCl) during seed germination. The uptake of water, and levels of Na+ and K+ of salt sensitive and salt tolerant cultivars, before and after imbibition, were measured to determine the contributions of ionic and osmotic factors to seed different response to salt stress. Imbibition of seeds incubated with NaCl solutions was reduced by approximately 5% for each 100mM increase in NaCl concentration once the level of 100mM NaCl was reached. The Na+ concentration of seeds after imbibition did not differ significantly among cultivars and selective uptake or exclusion of Na+ were not associated with the differences in salinity tolerance. No differences between the two tested cultivars were noted for initial K+ concentration, but the salt tolerant cultivar lost less K+ relative to Na+ uptake than did the salt sensitive cultivar. The adver...

Nitrogen and protein metabolism in young pea plants as affected by different concentrations of nickel, cadmium, lead, and molybdenum

Abstract: A comparative study was carried out on the effect of molybdenum (Mo), nickel (Ni), cadmium (Cd), and lead (Pb) using concentrations of 1×10− 7, 1×10− 5, and 1×10− 3 mol dm− 3, on the metabolism of nitrogen and proteins in young pea plants (Pisum sativum L. ‘NS Lim’). The highest concentrations of the investigated metals were noted to suppress the development of the aboveground parts and roots. The smallest inhibiting effect was observed in the presence of Ni, which at lowest concentration produced a stimulating effect; Pb and Cd had a similar effect. The most pronounced inhibition was caused by Mo, which decreased the growth of the roots and aboveground parts by 50% and 35%, respectively. An increase in concentration of heavy metals in the medium resulted in their increased accumulation in both the plant roots and aboveground parts. The largest accumulation in the aboveground parts was observed for Ni and Mo, followed by Cd, and least for Pb. Nitrate and protein metabolism decreased according to the order...

Mycorrhizal influence on fruit yield and mineral content of tomato grown under salt stress

Abstract: Tomato (Lycopersicon esculentum Mill.) yields are known to decrease for plants grown in saline soils. This study was conducted to determine the effects of arbuscular mycorrhizal fungi (AMF) inoculation on fruit yield and mineral content of salt-tolerant and salt-sensitive tomato cultivars grown with varied levels of salt. NaCl and CaCl2were added to soil in the irrigation water in equal molar ratios to give ECe values of 1.4 (nonstressed) and 4.9 dS m−1 (salt stressed). Plants were grown in a greenhouse using unsterilized, low phosphorus (P) (silty clay) soil-sand mix. Mycorrhizal root colonization occurred whether cultivars were salt stressed or nonstressed, but the extent of AMF root colonization was higher in AMF inoculated than uninoculated plants. The salt tolerant cultivar ‘Pello’ generally had higher AMF root colonization than the salt sensitive cultivar ‘Marriha’. Shoot dry matter (DM) yield, fruit fresh yield, and AMF colonization were higher for plants grown under nonstressed than for plants gro...

Canopy photosynthesis, specific leaf weight, and yield components of cotton under varying nitrogen supply

Abstract: Nitrogen (N) nutrition greatly affects the number of nodes above the uppermost white flower (NAWF), an indicator of plant growth and development in cotton (Gossypium hirsutum L). In this study, we examined relationships of NAWF with canopy photosynthesis (CP), specific leaf weight (SLW), and yield components, boll number, and dry weight in cotton under varying N supply. Four pre-plant soil incorporated fertilizer N treatments were imposed on long-term N fertilizer plots (fine-silty, mixed, thermic Typic Fragiudalt); 0, 55, 82, and 110 kg N ha−1. Soil N level had a dramatic effect on NAWF, CP, SLW, and yield components, all of which increased with increasing soil N level. However, CP and NAWF declined as the season progressed under all four soil N levels. Canopy photosynthesis, SLW, and yield components were closely associated with NAWF as the soil N increased from 0 to 110 kg N ha−1. Also, the photosynthetic capacity of the canopy was strongly related to SLW under increasing soil N. These relationships of...

Uptake of thallium by vegetables: its significance for human health, phytoremediation, and phytomining

Abstract: Eleven common vegetables (green bean, beetroot, green cabbage, lettuce, onion, pea, radish, spinach, tomato, turnip, and watercress) as well as the thallium hyperaccumulator Iberis intermedia, were grown in pot trials containing 0.7 and 3.7 mg/kg thallium added to a silt loam soil. The aims of the experiments were threefold: to estimate risks to human health of vegetables grown in thallium-rich soils, to demonstrate the potential of crops of these plants to remove thallium from polluted soils (phytoremediation), and finally to establish the degree to which part of the costs of remediation could be recouped by selling the extracted thallium (phytomining). Maximum thallium levels ranged from nearly 400 mg/kg (d.m.) in Iberis down to just over 1 mg/kg in green bean. The four vegetables with the highest thallium levels (watercress, radish, turnip and green cabbage) were all Brassicaceous plants, followed by the Chenopods beet and spinach. At a thallium concentration of 0.7 mg/kg in the soil only green bean, t...

Allometry to estimate leaf area of tomato

Abstract: Possibilities and limits of leaf area determination without destruction of leaves were examined. Length and width of tomato leaves (Lycopersicon spp.) were measured in different experiments. Allometry was examined, and its robustness was analyzed against treatment factors including genotype, salinity of the nutrient solution, growing system, and date of measurement. Total leaf length alone explained 75% of tomato leaf area variance. Length from the rachis to the distal end of the petiole had the same variance as total length. Leaf area estimation was much better using only leaf width, which accounted for 90% of leaf area variance. No further improvement of estimation was possible by using both length and width. Leaf area estimation from leaf length or width was robust across treatment factors investigated, including growing system, salinity of nutrient solution, and for different measurement date. On the other hand, use of an universal relationship may lead to a considerable systematic error of estimation...

Evaluation of effects of nitrogen and magnesium fertilization on rice yield and fertilizer nitrogen efficiency using 15n tracer technique

Abstract: Rice crop suffers from magnesium (Mg) deficiency in many locations of Muda Irrigation Scheme, Kedah, Malaysia. As a result nitrogen (N) efficiency is low in rice culture. It is necessary to evaluate the effects of Mg fertilization on rice yield and N use efficiency. A greenhouse experiment was conducted at Universiti Putra Malaysia during May to September 1998 to evaluate the effects of N and Mg fertilization on rice yield and fertilizer N efficiency in two soils (Guar and Hutan series). Nitrogen was applied as 15N labeled urea. Nitrogen and Mg application increased grain yield significantly in both the soils. Regression analysis indicated that estimated grain yield response to added N was linear in Guar series while it was quadratic in Hutan series. Estimated grain yield response to added Mg was quadratic in nature in both the soils. 15N atom excess in both grain and straw increased significantly with increasing N rates. Magnesium fertilization increased fertilizer N uptake and recovery (%) of fertilizer...

Soil and plant tests to predict optimum nitrogen rates for corn

Abstract: Optimum fertilizer nitrogen (N) rates are highly variable from one production corn (Zea mays L.) field to another, but producers usually use about the same N rate over their whole farm. Matching N application rates to actual crop need could have both economic and environmental benefits. The objectives of this research were to evaluate soil and plant tests for their ability to predict optimum N rates across a range of production cornfields in Missouri, and to evaluate the economic performance of recommendation systems based on these measurements. Yield response to N was measured in each experiment, along with soil mineral N measurements (planting and sidedress), tissue N at sidedress time, and chlorophyll meter reading at sidedress time. Optimum N fertilizer rates were fairly evenly spread from 0 to 235 kg N ha−1 in these sixteen experiments. Soil N measurements, tissue N at sidedress, and chlorophyll meter reading at sidedress were all clearly related to optimum N rate—the higher the test result, the lowe...

Effectiveness of different foliar iron applications to control iron chlorosis in orange trees grown on a calcareous soil

Abstract: The effectiveness on controlling Fe chlorosis in orange trees grown on calcareous soils was tested. The treatments were Fe(II) sulfate (500 mg Fe L−1), sulfuric acid (0.5 mM H2SO4), Fe(III)-chelate (Hampiron 654 GS, 120 mg Fe L−1) and distilled water as a control. A non-ionic wetting agent was used in all treatments. The use of frequent foliar sprays alleviated Fe chlorosis in orange trees. Sprays of Fe(II) sulfate increased the concentrations of chlorophyll, Fe and zinc in leaves and improved fruit size and quality compared to fruits of control trees. Sprays of Fe(III)-chelate also increased leaf chlorophyll and Fe concentrations and improved fruit quality, but did not increase fruit size. Sprays of sulfuric acid alone slightly increased leaf chlorophyll and Fe concentrations, without improving fruit size and quality. These results suggest that foliar sprays with Fe could help to avoid yield and quality losses caused by Fe chlorosis in citrus orchards. Furthermore, these treatments could be done with rel...

Influence of succinate on zinc toxicity of pea plants

Abstract: The response of pea plants (Pisum sativum, cv. Citrine) to various zinc (Zn) concentrations (0.67 to 1000 μM Zn) in the presence and absence of succinate (200 μM Na-succinate) were investigated. Treatment of pea plants alone with excess of Zn reduced plant growth, chlorophyll content and induced alterations in the structure of the chloroplast, resulting mainly in decreased granal thylakoids. The photochemical activity of photosystem II estimated by the ratios Fv/Fm and Fv/Fo was less affected by Zn treatment. The presence of succinate lead to an increase in plant growth and chlorophyll content, improved chloroplast structure of and recovered photosystem II activity in Zn-treated plants. This stimulation was accompanied by an increased zinc root concentration and a decreased zinc shoot concentration. The higher root zinc concentration and decreased zinc translocation from root to shoot by succinate treatment suggest that succinate facilitates the formation of metal-succinate complexes in the roots and may ...

Effects of salinity and macronutrient levels on micronutrients in wheat

Abstract: It is unclear how salinity and macronutrients affect the micronutrient composition of plants. The objective of this study was to investigate interactive effects of salinity and macronutrients on micronutrient concentration in leaves, stems, and grain of spring wheat (Triticum aestivum L. cv. Lona) grown in hydroponics in growth chambers. Eight salinity levels from 0 to 150 mM NaCl, and 1, 0.2, and 0.04 strength Hoagland macronutrient solutions were used. It was found that the effects of salinity on the concentrations of Mn, Zn, Fe, and B in plants were complex. The changes in Mn, Zn, Fe, and B concentrations under saline conditions depended upon the levels of macronutrients and salinity, and the organs of plants. There was no significant correlation between yield parameters and Mn, Zn, Fe, and B in wheat, regardless of the macronutrient levels. This finding suggests that the micronutrient concentration in plants is probably not much affected by salinity.

Survival of rhizobia/bradyrhizobia and a rock-phosphate-solubilizing fungus aspergillus niger on various carriers from some agro-industrial wastes and their effects on nodulation and growth of faba bean and soybean

Abstract: Coculturing of eight rhizobial strains (Bradyrhizobium japonicum USDA 110, USDA 3447, RCR 3407, RCR 3442, Rhizobium meliloti TAL 1372, TAL 1373, R. leguminosarum biovar viceae RCR 1001, and RCR 1044) and five rock-phosphate-solubilizing fungi (Aspergillus egyptiacus, A. flavus, A. niger, A. ochraceus, and Penicillium citrinum) was tested on yeast extract-mannitol agar. B. japonicum strains USDA 110, USDA 3447, RCR 3442, R. leguminosarum biovar viceae RCR 1001, and RCR 1044 grew successfully in cocultures with the tested fungal species in yeast extract-mannitol agar without antagonism. Among these fungi, A. niger showed the highest potentialities to solubilize rock- phosphate at all incubation temperatures examined (15, 28, 38, and 42°C), and phosphate dissolution maximized at 28°C. Survival of Rhizobium/Bradyrhizobium strains and the best rock-phosphate-solubilizing fungus (A. niger) was evaluated monthly in four carrier materials (Peat, wheat bran, sugarcane baggase, and wheat straw) at 28 and 38°C. The ...

Salt tolerance and salt accumulation of landscape plants irrigated by sprinkler and drip irrigation systems

Abstract: Field trials were conducted to evaluate salt tolerance of landscape plants for recycled-water irrigation. Ten selected landscape plant species exhibited substantial differences in salt tolerance. Plants with more tolerance to salt tend to accumulate less salt than less salt tolerant plants. Plants were more susceptible to salt stress under sprinkler irrigation than under drip irrigation, because leaf direct contact with salt. No apparent salt stress symptom was detected when plants were irrigated by drip irrigation either with 500 mg L−1 or 1500 mg L−1 salt (NaCl). Therefore, drip irrigation using recycled water may be accept-able for many landscape plants in California landscape. There was a positive relationship between the salt tolerance revealed by sprinkler irrigation and the salt tolerance revealed by drip irrigation. This positive relationship is a potentially useful character to screen for salt tolerant landscape plants. Selection for salt tolerant landscape plants for recycled water irrigation is...

Compilation of simple spectrophotometric techniques for the determination of elements in nutrient solutions

Abstract: A compilation of simple spectrophotometric techniques for the determination of components in a nutrient solution is presented. These techniques are suitable for the determination of nitrate, phosphate, sulfate, chloride, ammonium, and silicon concentrations. Protocols for these determinations are detailed together with examples of standard calibration curves for these nutrient elements obtained in our laboratory. These protocols enable the routine and sensitive measurements of nutrient solution composition requiring only a spectrophotometer and minimal use of other basic laboratory equipment.

Effect of toxic iron concentrations on the growth of lowland rice

Abstract: Iron (Fe) toxicity is a complex and major nutritional soil constraint affecting rice production in the irrigated and rainfed lowland soils in various parts of the World, including West Africa and Nigeria in particular. Data related to the reaction of rice cultivars especially ITA 212 and Suakoko 8 in the West Africa sub-region to Fe concentrations is sparse. A pot experiment was conducted involving these two rice cultivars, two soil types with previous history of Fe-toxicity and four Fe2+ levels (control, 1000, 3000, and 4000-mg Fe2+ L−1). The experiment was a factorial design with the treatments arranged in a completely randomized fashion with three replications. The effects of various Fe-levels were measured on bronzing symptoms, tissue nutrient contents, plant height, tiller numbers/pot, at 30, 60, and 90 days after transplanting (DAT) while grain and dry matter yields were measured at harvest. The results clearly showed that with increasing Fe2+ levels, tissue phosphorus (P), potassium (K), and mangan...

Effects of nitrogen forms on growth, nitrate accumulation, membrane permeability, and nitrogen use efficiency of hydroponically grown bunch onion under boron deficiency and toxicity

Abstract: The objectives of this study were to determine the effects of nitrogen (N) forms and deficient and toxic rates of boron (B) on the growth, NO3 accumulation, membrane permeability, mineral nutrition, and nitrogen use efficiency (NUE) of bunch onion (Allium cepa L. var. Radar) plants. Therefore, 20% of NO3 in reference nutrient solution was replaced by NH4, urea, or mixed amino acids (AA). To each of these solutions 3, 30, or 300 mmol m−3 B was added. Fresh and dry weights were the same in the reference and mixed AA treatments, but NH4 and urea decreased these growth parameters as compared to the reference. Mixed AA decreased the NO3-N content while urea increased it, and NH4 treatment yielded similar NO3-N content as compared to the reference. The nitrogen content of plants was increased by NO3 replacement with either NH4 and, urea or mixed AA. At the 300 mmol m−3 B rate, B content of plants was decreased by NH4 and urea, but increased by the mixed AA treatment. Membrane permeability was increased by NH4␣r...

Effects of three rootstocks on photosynthesis, leaf mineral nutrition, and vegetative growth of “bc-2 fuji” apple trees

Abstract: Net photosynthesis (Pn), leaf nutrition, and current terminal shoot (CTS) growth of ‘BC-2 Fuji’ apple [Malus sylvestris (L) Mill vardomestica (Borkh) Mansf] trees on three rootstocks, Budagovski (Bud) 9, Ottawa 3, and M7 EMLA under field conditions were studied in 1998 and 1999 Rootstock affected the scion leaf Pn, leaf mineral concentrations, and vegetative growth Leaves of trees on Bud9 had lower Pn than those on the other rootstocks, and the differences were significant in 1999 Scion leaves on Bud9 had higher calcium (Ca) and manganese (Mn) but lower potassium (K) concentrations than those on the other rootstocks Leaves of trees on M7 EMLA had significantly higher magnesium (Mg), K, and copper (Cu) concentrations than those on the other rootstocks in both years Trees on Ottawa 3 had significantly lower leaf Cu concentrations than those on the other rootstocks during both 1998 and 1999 Trees on Bud9 rootstock had shorter limbs and terminal shoots than those on the other rootstocks in 199