Boron and ectomycorrhizal influences on mineral nutrition of container‐grown Pinus ehinata mill

Boron fertilization and inoculation with Pisolithus tinctorius (Pers.) Coker and Couch increased foliar and total seedling nutrient content of boron, calcium, copper, iron, potassium, magnesium, manganese and phosphorus in shortleaf pine seedlings (Pinus echinata Mill.). Noninoculated seedlings fertilized with boron showed no increase in nutrient content other than B. The increase in nutrient content of inoculated seedlings fertilized with boron was correlated with increased mycorrhizal infection. Boron fertilization may affect indirectly the mineral nutrition of tree seedlings by increasing mycorrhizal fungi colonization of their roots.     

Nitrogen fertigation of greenhouse‐grown tomato

Abstract

This greenhouse study was conducted to determine the response of trickle‐irrigated tomato (Lycopersicon esculentum cv. Dombo) to 6.4, 12.8, or 19.2 mmol N/L applied via the irrigation stream. The plants were grown in pots filled with 12 kg of soil. The amount of N applied in a total of 438 L of water per plant was 39.4, 78.8, or 118.2 g for the three N levels, respectively. The residual NO₃‐N concentration in the root volume was negligible with the 6.4 mmol N/L treatment, whereas, with the highest N level increased sharply for the first 16 weeks before reaching a value around 32 mmol N/L, which continued for the remainder of the experiment. With the highest N level there was also increase of soil solution EC, and NO₃‐N concentration in laminae and petioles was in excess. With the lowest N treatment, NO₃‐N concentration in laminae and petioles was at deficient levels. With 12.8 mmol N/L, NO₃‐N in petioles and laminae was at the sufficient level and yet no substantial increase of soil solution EC or NO₃‐N concentration occurred, suggesting efficient use of N by crop. The highest yield (12.6 kg marketable fresh fruit per plant) was obtained with 12.8 mmol N/L due to increased number of fresh weight of fruits. It was concluded that 12.8 mmol N/L applied via the irrigation stream is adequate for high tomato yield without unduly raising soil salinity or wasting fertilizer N.     

Stem infusion of field‐grown maize

Abstract

Field experiments were conducted in summer 1992 on the Central Experimental Farm, Ottawa (45°22'N, 75°43'W) to determine whether a stem infusion technique developed for maize under controlled conditions was applicable to field‐grown maize and to evaluate whether providing sucrose in solution at silking via stem infusion altered plant source‐sink relationships sufficiently to increase kernel set. The higher and more variable evaporative demand and more difficult installation under field conditions dictated modifications to the stem infusion apparatus to prevent leakage and to facilitate assembly prior to field set‐up. A range of several field parameters were tested to identify conditions that would maximize infusion of sucrose solution: raising the syringe barrel height increased the volume of solution uptake; the largest amount of sucrose was taken up using a concentration of 150 g sucrose L^‐1, and consecutive multiple infusions of the same plant increased solution uptake. Solution uptake was found to be greatest in the first 24 h of infusion. Leaf soluble carbohydrate and starch concentrations and ear leaf photosynthesis were not changed by sucrose infusion. Sucrose solution infused at silking appeared to increase kernel set in one of the experimental hybrids.     

Response of field‐grown soybeans to lime

Abstract

Studies were conducted to; (1) measure the detrimental effects of manganese toxicity on vegetative and reproductive growth of soybeans, and (2) measure the influence of liming on the availability and uptake of manganese.

The data suggests that the cultivar Forrest may be more sensitive than either Bragg or Lee 68 to manganese concentrations but this is not reflected in foliar levels. Liming the soil to pH 5.5 or above significantly reduced the concentration of extractable soil manganese, decreased foliar concentrations and eliminated the toxic effects, and increased the yields.

Soybean yields and foliar manganese concentrations correlated better with NH₄OAc‐ or CaCl₂‐extractable manganese than with water‐soluble manganese.     

Distribution of sludge‐borne manganese in field‐grown maize

Abstract

The uptake and distribution of manganese (Mn) in field‐grown maize (Zea mays L.) was studied in a long‐term sewage sludge field trial on an acid sandy soil at Bordeaux. Since 1974, sewage sludge had been applied at levels of 101 dry matter (DM) ha^‐1 year^‐1 (SS 10) and 1001 DM ha^‐1 per 2 years (SS 100) on annually cropped maize plots. Treatment with farmyard manure (FYM) at a rate of 10 t DM ha^‐1 year^‐1 served as unpolluted control. Five replicate plants per treatment were examined at six different growth stages. At each stage, the whole plant was separated into its different organs and the Mn distribution was determined in at least 12 different plant parts. Manganese concentrations were always higher in SS 100 plants compared to FYM and SS 10 treated plants. Significant treatment‐dependent differences occurred almost all in the roots and in the different leaf levels while we found similar Mn concentrations in the stalk and in the reproductive organs. In the different stalk levels and in the ear composites we determined low Mn concentrations with critical deficiency values in FYM and SS 10 plants while Mn concentrations in SS 100 plants were in the normal range. Soil treatment also significantly influenced the initial absorption by the roots. Despite low absolute Mn concentrations in the roots of FYM plants, the Mn transfer coefficient (plant Mn concentration/soil Mn concentration) was highest in FYM plants and lowest in SS 100 plants indicating a relatively low Mn plant availability in the sludge‐treated plots.     

Influence of shade on mineral nutrient status of field‐grown cotton

Photosynthetic irradiance has variable effects on cotton (Gossypium hirsutum L.) growth, development, lint yield and fiber quality. However, little is known about the effect of shade on the mineral nutrient status of cotton plants. A two‐year study was conducted to determine the effects of shade (63% light reduction) at different growth stages on mineral nutrient concentrations in plant components of field‐grown cotton. Averaged over the three growth stages of first flower, peak flower, and boll development, an 8‐day period of shade increased petiole NO₃‐N, phosphorus (P), potassium (K), and sulfur (S) concentrations by 145, 17, 20, and 18%, respectively. Total nitrogen (N), P, K, S, calcium (Ca), and magnesium (Mg) concentrations in the leaf blades of the sampled petioles increased 19, 29, 22, 22, 13, and 16%, respectively, compared with those of unshaded control plants. However, bracts and floral buds of 20‐day‐old squares of shaded cotton plants showed a slight decrease (6%) in total N concentration, and increases in the other mineral nutrient concentrations. The increased mineral nutrients of shaded plants were closely associated with decreased carbohydrate accumulation. Shade during plant reproductive growth significantly affected nutrient status and TNC/N ratio of cotton. This study indicated that light intensity at the time of sampling can cause non‐representative nutrient analysis and erroneous diagnostic recommendations. Therefore, the time of day and light conditions must be considered when sampling cotton petioles and other tissues for nutrient diagnoses.     

Cation exchange capacity of two‐component container media predicted from laboratory analysis of components

Abstract

A mathematical equation predicting cation exchange capacity (CEC) of pine bark‐sand container media from CEC of the individual components was formulated. The equation is the weighted sum of milliequivalents contributed by each component and is corrected for shrinkage due to mixing of components. Both measured and predicted CEC increased linearly with increasing percent volumetric bark in pine bark‐sand media. Regression equations describing measured and predicted CEC were not statistically different. The predictive equation was also tested on 6 non‐synthesized 2‐component media prepared from peat moss, perlite, pine bark, vermiculite, and sand. No statistical differences between measured and predicted CEC were obtained.     

Root responses of sterile‐grown onion plants to iron deficiency 1

Onion (Allium sativum) plants grown without iron (Fe) in sterile nutrient solutions readily developed chlorosis symptoms. Iron deficiency in the sterile‐grown plants stimulated the rates of root extracellular reduction of Fe³⁺, copper (Cu²⁺), manganese (Mn⁴⁺), and other artificial electron acceptors. While rapid reduction occurred with the synthetic chelate Fe³⁺HEDTA, no short‐term reduction occurred with the fungal siderophore Fe³⁺ferrioxamine B (FeFOB). In addition to the increased rate of extracellular electron transfer at the root surfaces, the Fe‐deficient plants showed greater rates of Fe uptake and translocation than the onion plants grown with Fe. The rates of uptake and translocation of Fe were sharply higher for the Fe‐deficient plants supplied with FeHEDTA than for similar plants supplied with FeFOB. Inhibition by BPDS of the Fe uptake by the Fe‐deficient onion plants further supported the importance of Fe³⁺ chelate reduction for the uptake of Fe into the roots. Rates of Fe uptake and translocation by Fe‐deficient onion plants supplied with ⁵⁵FeFOB were identical to the rates of uptake of ferrated [14C]‐FOD; a result that gives evidence of the uptake and translocation of the intact ferrated siderophore, presumably by a mechanism not involving prior extracellular Fe³⁺ reduction. Differences in the rates of transport of other micronutrients into the roots of the Fe‐deficient onion plants were evident by the significantly higher Zn and Mn levels in the shoots of the Fe‐deficient onion.     

Effect of various potassium‐calcium ratios on cation nutrition of grape grown hydroponically

The effect of potassium (K)‐calcium (Ca) ratios on the cation nutrition of Vitis vinifera L. cv. Négrette was investigated on grafted vines grown hydroponically to gain a deeper insight into the origin of the lack of acidity of some wines. Four nutrient solutions were investigated for long duration experiments: a balanced K‐Ca nutrient solution (K=3.9 meq L^‐1 ; Ca=4.8 meq L^‐1) used as a reference, a low K (K=0.3 meq L^‐1; Ca=8.4 meq L^‐1) and a high K (K=7.1 meq L^‐1; Ca=1.6 meq L^‐1) nutrient solutions. Besides, the reference nutrient solution was enriched with Ca (K=3.9 meq L^‐1; Ca=13.8 meq L^‐1) so as to simulate the possible effects of liming. The experiments showed that, in spite of low K requirements, the high K storage capacity of cultivar Négrette might account for the low acidity of the wines. However, a strong Ca‐K antagonism was characterized: the Ca enrichment of the reference nutrient solution resulted in a 30% decrease in the K concentration of leaf blades and petioles. Liming can thus limit K uptake by the plant and contribute to increased acidity of the wines issued from cultivars grown in acid soils.     

Effect of nitrate concentration on hydroponially grown primocane‐fruiting red raspberries

Primocane‐fruiting red raspberry plants (Rubus idaeus L.) ‘Redwing’ were grown in six hydroponic solutions containing nitrogen (N) levels of 2.5, 5, 10, 15, 20, and 25 meq N per liter. Plant growth rates and final cane heights were similar in all treatments except for reduced growth in the 2.5 meq per liter treatment. Greatest leaf, stem, and root dry weight accumulation was found in the 10 meq per liter treatment. The greatest numbers of nodes, flowers, and inflorescences per cane were found in the 5, 20, and 10 meq per liter treatments, respectively. Solution N levels had no effect on time of flowering.     

Use of labeled sulphur‐35 for tracing sulphur transfers in developing pods of field‐grown oilseed rape

Abstract

This study was conducted to better understand the dynamics of sulphur (S) transfer between pod walls and seeds of field‐grown oilseed rape by using sulphur (³⁵S) as an investigative tool. Labeling experiments with ³⁵S were carried out to determine the effects of nitrogen (N) and sulphur fertilization on these transfer mechanisms. Sixty‐four plants from field trials fertilized with 200 kg N ha^‐1 in the forms of ammonium nitrate (AN) or urea (U), with or without 75 kg S ha^‐1 in the forms of ammonium thiosulphate and MgSO₄ were sampled. At 30, 43, 56, and 77 days after flowering (DAF), terminal racemes were cut and labeled with ³⁵S‐SO₄ ^2‐. After labeling, pods and seeds were separated into 3 groups according to their position on stem, and measurements of ³⁵S levels were performed accordingly. This short‐term labeling experiment showed that the pod walls retained from 39 to 61% of labeled ³⁵S, according to the different treatments, whereas seeds accumulated from only 1 to 16% of applied ³⁵S. On average, when S was added, a sharp decrease of ³⁵S in seeds from 2.6 to 1.7%, 9.0 to 5.4%, and 14.8 to 7.7% was observed at 30, 43, and 56 DAF, while progressively the percentage values in pod walls increased from 49.6 to 50.5%, 43.1 to 52.2%, and 41.7 to 63.5%, respectively. The increase of ³⁵S in pod walls was found to be tied to the glucosinolate concentration of seeds. By artificially increasing the ratio values of external N‐NO₃ ^‐ to S‐SO₄ ^2‐, these results demonstrated that the transfer of ³⁵S to seeds was more affected by the higher level of N‐NO₃ ^‐ in plant tissues than S‐SO₄ ^2‐ levels. The N/S ratio value above which the transfer of S was disrupted was around 6.     

Impact of Boron on Biomass Production and Nutrition of Aluminum‐Stressed Apple Rootstocks

Abstract

The aim of the experiment was to examine the effect of boron (B) on biomass production and nutrition of aluminum (Al)‐stressed apple (Malus sp.) rootstocks. The study was carried out under greenhouse conditions on Polish rootstock (P22) and Malling 26 (M.26) planted singly into 1‐L plastic pots filled with perlite and supplied with Hoagland's medium at pH 4.5 without or with Al (100 µM as AlCl₃). Boron was added into the Al‐containing medium at 20, 40, or 60 µM whereas into the medium without Al only at 20 µM as boric acid. The results showed that the presence of Al in the medium reduced biomass production of P22 and M.26 rootstocks by 22% and 41%, respectively. Rates of uptake and translocation of phosphorus (P), magnesium (Mg), and calcium (Ca) to aerial plant parts were decreased for Al‐treated rootstocks. Aluminum‐stressed P22 rootstocks grown in nutrient solution at 40 and 60 µM B had higher dry weight of leaves and roots, and also higher ability to take up P, Mg, and Ca and lower Al than those grown in the presence of Al at 20 µM B in the medium. Rates of absorption and transport of B to aerial plant parts corresponded with B level in the medium. These results suggest that on acid soils with high Al availability, supra‐optimal B concentrations in soil solution (40–60 µM) can prevent/alleviate Al toxicity in apple trees grafted on P22 rootstocks.     

Yield of iron‐sprayed and non‐sprayed strawberry cultivars grown on high ph calcareous soil

Abstract

Iron (Fe) deficiency chlorosis (FeDC) results in extensive reduction in yield of strawberry (Fragaria x ananassa Duch.) grown on high pH calcareous soils. Three cultivars differing in response to FeDC were grown on a high pH (8.2) calcareous soil (25.4% calcium carbonate equivalent in surface 20 cm) in the field (Choueifat, coastal area of Lebanon) to determine the effects of FeDC on fruit yield of cultivars sprayed with FeEDDHA [ferric ethylene‐diiminobis (2‐hydroxyphenyl) acetate]. The unsprayed plots were used as a control. No significant interaction (P<0.05) between cultivars x FeEDDHA spray treatment, and no significant differences (P<0.05) between one and two FeEDDHA spray(s)/week treatment was noted for visual FeDC, fruit number, and fruit yield. Sprayed cultivars once a week produced higher yields than unsprayed ones; overall increases were 33% (13% for ‘Motto’, 30% for ‘Chandler’, and 56% for ‘Douglas'). Even though only slight FeDC was noted on the ‘Motto’ cultivar receiving no Fe EDDHA spray, fruit yields were increased when sprayed with FeEDDHA. However, significant increases in yield for ‘Chandler’ and ‘Douglas’ cultivars with severe FeDC ratings were rioted when sprayed with FeEDDHA.     

Behavior of iron‐inefficient plants when grown in combinations of calcareous and noncalcareous soils

Abstract

When Fe‐inefficient plants were grown in mixtures of calcareous Hacienda loam soil and noncalcareous Yolo loam soil compared with plants grown in unmixed soils, characteristics and composition of the plants including Fe deficiency were generally intermediate to those with either soil alone. Noncalcareous soil adjacent to calcareous soil allowed PI 54619–5–1 soybeans (Glycine max L.) to obtain sufficient Fe.     

Leaf‐tissue silicon content of sugarcane genotypes grown on everglades histosols 1

On soils low in plant‐available silicon (Si), fertilization of sugarcane (Saccharum spp.) with calcium silicate slag increases plant Si content and sugar yield. However, Si fertilization is costly. Plants which are more efficient in accumulating available Si may have an economic advantage, and selection for genotypes with greater Si content may be warranted. The purpose of this study was to determine if there was genetic variability for plant‐tissue Si content in selected populations of commercial‐type sugarcane clones in the Canal Point (CP), Florida breeding program. A total of 52 sugarcane genotypes from the third and fourth stages of the sugarcane breeding program were evaluated for Si content in leaves. Clones were evaluated as plant cane in randomized complete‐block experiments at four sites which varied in plant‐available Si. Soils at three sites were organic Histosols; the fourth was a sand. The locations and the forty Stage HI clones varied significantly (P<0.01) in plant‐tissue Si. Stage P7 test sites also varied significantly, but the 12 clones, which were of a narrower genetic base, did not. In both tests, ‘CP 72–1210’, a very popular and high‐yielding commercial cultivar, had the greatest mean Si content. Results indicated that genotypic variability for Si content exists in elite, commercial‐type sugarcanes. A greater range of Si content might be found in a more diverse array of genotypes. A study to investigate the heritability and stability of plant tissue Si content should be feasible.     

The influence of soil aeration on growth and elemental absorption of greenhouse‐grown seedling pecan trees

Abstract

‘Dodd’ pecan seedlings were exposed to 3 levels of soil aeration for 30 days; 100%, 5%, and 0% of the container surface exposed to the atmosphere. These treatments resulted in about 21%, 13.5%, and 3% soil O₂and 0.3%, 5%, and 13% soil CO₂for 100%, 5%, and 0% of the container surface exposed, respectively. Restricting soil aeration induced partial stomatal closure, and decreased leaf number, leaf area, and leaf, trunk and root dry weights. The decrease in root dry weight associated with reduced soil aeration exceeded the decrease in top dry weight by about 50%. Translocation of N and P to the leaves was reduced when soil aeration was restricted, but root N and P concentrations were increased compared to trees grown in well aerated soil. Leaf elemental concentrations of Ca, Mg, and Mn were lower when trees were exposed to reduced soil aeration. Zinc and Fe concentrations were greater in the roots of trees with low aeration, but leaf and trunk concentrations of Zn and Fe were not affected     

Zinc toxicity‐induced variation of mineral element composition in hydroponically grown bush bean plants

Bush bean plants (Phaseolus vulgaris L. cv Contender) were grown for twenty days in nutrient solution (pH=5), containing 0.13, 0.3, 0.5 or 0.75 mg 1^‐1 Zn as ZnSO₄‐7H₂O. The plant yield decreased linearly with the increase of the Zn concentration supplied. The phytotoxic threshold content (for 10% growth reduction) was about 486, 242, 95 and 134^‐ μg Zn g^‐1 for roots, steins, mature primary and trifoliate leaves, and developing leaves, respectively. High inverse correlation coefficients with the Zh concentration supplied were found for the Mn content of all organs, for the P content of roots, and for the Cu and Ca contents of developing leaves. Significant positive relations were found for the Fe, Zn and Cu contents in roots and for the Zn con‐ tents in stems and fully expanded leaves. The ratios of the mineral contents between organs suggest inhibition of uptake of Mn and P, and inhibition of translocation of Fe, Cu and Ca. The relation between dry weight decrease and Zn‐induced nutrient content disorders were discussed.     

Control of arsenic toxicity in rice plants grown on an arsenic‐polluted paddy soil

Abstract

Paddy soils of over 500 hectares had been polluted by arsenic (As) from tailings at an abandoned lead‐zinc mine at Shaoxing, Zhejiang, China. Several field experiments were conducted to establish measures for reducing As toxicity to rice plants. The results obtained were as follows. Fresh Chinese milkvetch (Astragalus sinicus L.) was not supposed to be used as green manure in arsenic polluted paddy soils. Although liming (1,500 kg CaO hectare^‐1) could reduce water‐soluble As (H₂O‐As) in the soil, the rice plant grew badly. The treatments of FeCl₃ (25 mg Fe kg^‐1 soil) and MnO₂ (25 mg Mn kg^‐1 soil) could markedly lower the H₂O‐As and arsenite [As(III)] percentage in the soil and make the plant grow better than the control experiment (CK). Without adding any materials to the soil, wetting and drying (furrowing and draining) in the paddy soil could increase soil redox potential greatly and lower the H₂O‐As and As(III) percentage obviously leading to better rice growth. In addition, the As contents of roots, flag leaf, grain, and husked rice of 11 new cultivare of early rice were determined and correlation analysis was conducted. Uptake and accumulation of As in different parts of cultivars Zhefu‐802 and Erjiufeng at the 4 As levels of the paddy soil demonstrated that the As contents in husked rice of both cultivars exceeded the hygienic standard (0.7 mg As kg^‐1) when they grew in the paddy soil having total As content of about 70 mg kg^‐1 for Zhefu‐802 and 100 mg kg^‐1 for Erjiufeng, respectively.     

Modeling approach to nitrogen uptake by field‐grown corn

Although the plant root system is one of the most important plant parameters affecting nutrient uptake by plants, root studies in field experiments are rarely conducted in plant nutrition and fertility studies. Since collection of root samples and measurements are difficult and time consuming, they are not considered as a routine plant parameter. Therefore, the effect and importance of the corn root system on plant nitrogen (N) uptake and grain yield was studied under field conditions in Adana, Turkey. Nitrogen was applied at rates of 200, 250, 300, and 350 kg N ha^‐1 as urea in a randomized complete block design experiment with three replications. During course of the experiment, soil, plant, root, and grain samples were collected and prepared for chemical analysis. Nitrogen uptake by plants was predicted using a COMP8 mathematical computer model and compared to actual plant uptake. Grain yield and leaf N content increased with increasing N rates, but root length did not change statistically. Predicted N uptake increased with added N, but was much smaller than observed N uptake under field conditions. Consequently, additional soil and plant parameters should be considered in nutrient uptake models to make the prediction more sensitive.     

Previous Corn Row Effects on Potassium Nutrition and Yield of Subsequent No‐Till Soybeans

Abstract

Narrow‐row soybean [Glycine max (L.) Merr.] production in corn [Zea mays L.]–soybean rotations results in various distances of soybean rows from previous corn rows, yet little is known about soybean responses to proximity to prior corn rows in no‐till systems. The objective of this study was to evaluate the impacts of preceding corn rows on potassium (K) nutrition and yield of subsequent no‐till soybeans. Four field experiments involving a corn–soybean rotation were conducted on long‐term no‐till fields with low to medium K levels from 1998 to 2000 near Paris and Kirkton, Ontario, Canada. In the corn year, treatments included K application rate and placement in conjunction with tillage systems or corn hybrids. Before soybean flowering, soil exchangeable K concentrations (0–20 cm depth) in previous corn rows were significantly higher than those between corn rows. At the initial flowering stage, trifoliate leaf K concentrations of soybeans in preceding corn rows were 2.0 to 5.3 g kg^?1 higher than those from corresponding plants between corn rows. Yield of no‐till soybeans in previous corn rows increased 10 to 44% compared to those between previous corn rows. Positive impacts of prior corn rows on soil K fertility, soybean leaf K, and soybean yield occurred even when K fertilizer was not applied in the prior corn season. Deep banding of K fertilizer tended to accentuate row vs. between‐row effects on soybean leaf K concentrations in low‐testing soils. Corn row effects on soybeans were generally not affected by either tillage system or corn hybrid employed in the prior corn crop. Potassium management strategies for narrow‐row no‐till soybeans should take the potential preceding corn row impacts on soil K distribution into account; adjustments to current soil sampling protocols may be warranted when narrow‐row no‐till soybeans follow corn on soils with low to medium levels of exchangeable K.