Growth and nutrient uptake of peach seedlings with varying magnesium concentrations at low pH 1

Soils of the peach growing region of the Southeastern Coastal Plain are highly leached and excessively acid, with inherently low concentrations of subsoil magnesium (Mg). A greenhouse experiment was conducted to determine the effects of varying Mg concentrations at low pH on growth and Mg uptake of three peach seedling cultivars commonly used as rootstock in the region. Seedlings of ‘Lovell’, ‘Elberta’, [Prunus persica (L.) Batsch] and ‘Nemaguard’ [Prunus persica (L.) Batsch X Prunus davidiana Carriere] were grown for 36 days in nutrient solution containing 9, 21, 42, 84, 167, 333, and 667 μM Mg. Magnesium concentration in solution did not increase lateral length, number of laterals, trunk cross‐sectional area, or root volume. All terminal growth responses were cultivar related. Magnesium concentration in the leaves, stems, and roots were increased either by quadratic or cubic relationship with solution Mg concentration while Mg uptake rate was increased linearly with solution Mg concentration with all three seedling cultivar. Uptake rates of calcium, manganese, and zinc, and tissue concentrations of phosphorus, manganese, and zinc decreased with increasing Mg concentrations in nutrient solution. Predicted Mg uptake rates by‐regression analysis revealed a cubic uptake isotherm for Nemaguard and a quadratic isotherm for Elberta. Predicted tissue Mg concentration followed similar patterns of accumulation for leaves and stems, but root Mg concentration followed a cubic uptake isotherm for all three seedlings. The linear Mg uptake at low pH may be an important physiological characteristic that enables Lovell seedlings to outperform either Elberta or Nemaguard when used as a rootstock in the southeastern soils.     

Growth and magnesium uptake of tall fescue lines at high and low potassium levels 1

Five tall fescue (Festuca arundinacea Schreb.) clonal lines with diverse root and xylem diameters were grown in nutrient solutions with magnesium (Mg) concentrations of 42, 125 and 250 μM and potassium K concentrations of 133 and 333 μM. Leaf Mg concentrations increased with increasing Mg rates at both low and high K concentrations. The tall fescue line with the largest root and xylem diameters had low leaf Mg concentrations, indicating a possible increased Mg tetany potential when consumed by cattle. The response of the K/(Mg+Ca) ratio in the plant, an indicator of tetany potential, to varying solution Mg at low and high K was determined for each of the five lines. No Mg effects or interactions were significant. Line, K, and line x K effects were all significant for the K/(Mg+Ca) ratios. The line with the largest root and xylem diameters had the highest tetany potential (highest cation ratio). Higher solution K gave higher K/(Mg+Ca) ratios.     

Neotyphodium coenophialum‐endophyte infection affects the ability of tall fescue to use sparingly available phosphorus

Neotyphodium coenophialum, (Morgan‐Jones & Gams) Glenn, Bacon & Hanlin, infected tall fescue (Festuca arundinacea Schreb.) plants perform better than non‐infected isolines on phosphorus (P)‐deficient soils. Our objective was to characterize growth and P uptake dynamics of tall fescue in response to endophyte infection and P source at low P availability in soil. Two tall fescue genotypes (DN2 and DN4) infected with their naturally occurring N. coenophialum strains (E+), and in noninfected (E‐) forms were grown in Lily soil (fine loamy siliceous, mesic Typic Hapludult) in a greenhouse for 20 weeks. Three soil P treatments were imposed: no P supplied (control) and P supplied as commercial fertilizer (PF) or as phosphate rock (PR) at the level of 25 mg P kg^‐1 soil. Interaction of tall fescue genotype and endophyte status had a significant influence on mineral element uptake suggesting high specificity of endophyte‐tall fescue associations. Endophyte infection did not affect root dry matter (DM) when no P was supplied but shoot DM was reduced by 20%. More biomass was produced and greater P uptake rate occurred in PR than PF treatment. Root DM was greater in E+ DN4 than E‐DN4 when supplied with either PF or PR. In contrast, endophyte infection did not affect root DM of DN2, regardless of P source. Relative growth rate (RGR) of E+ plants grown with PR was 16% greater than that of E‐plants. Endophyte infection did not improve growth or P uptake in PF treatment. When PR was supplied, P uptake rate was 24% greater in E+ DN2 than E‐ DN2, but endophyte infection did not benefit DN4. Phosphorus‐use efficiency was 6% less in E+ DN2 but 16% greater in E+ DN4 compared to E‐ plants, regardless of P source. Root exudates of E+ DN2, but not E+ DN4 solubilized more P from PR than those of E‐ plants. The correlation between root RGR and P uptake rate was relatively high for E‐ plants (r=0.76), but low for E+ plants (r=0.27) grown with PR. Results suggest that P uptake by E+ tall fescue might rely on mechanisms other than an increase in root biomass (surface area). Endophyte infection modified tall fescue responses to P source. This phenomenon was associated with modes of P acquisition which included enhanced activity of root exudates in releasing P from PR in E+ plants (DN2), and increased root biomass (DN4). The dominant means of P acquisition may be determined by a specific association of endophyte and tall fescue genomes. Endophyte‐tall fescue association plasticity contributes to widespread success of symbiotic in marginal resource conditions.     

Growth and nutrient uptake of temperate perennial pastures are influenced by grass species and fertilisation with a microbial consortium inoculant

Background: The low fertility of sandy soils in South‐Western Australia is challenging for the establishment of temperate perennial pastures. Aims: To assess whether microbial consortium inoculant may improve plant growth by increasing nutrient supply, root biomass and nutrient uptake capacity. Methods: Five temperate perennial pasture grasses–cocksfoot (Dactylis glomerata L. cv. Howlong), phalaris (Phalaris aquatica L. cv. Atlas PG), tall fescue (Festuca arundinacea L. cv. Prosper), tall wheatgrass (Thinopyrum ponticum L. cv. Dundas), and veldt grass (Ehrharta calycina Sm. cv. Mission) were tested in a controlled environment on the growth and nutrition with the microbial consortium inoculant and rock mineral fertiliser. Results: Veldt grass produced the highest shoot and root growth, while tall fescue yielded the lowest. Rock mineral fertiliser with or without microbial consortium inoculant significantly increased root and shoot biomass production across the grass species. The benefit of microbial consortium inoculation applied in conjunction with rock mineral fertiliser was significant regarding shoot N content in tall wheatgrass, cocksfoot and tall fescue. Shoot P and K concentrations also increased in the five grass species by microbial consortium inoculation combined with rock mineral fertiliser in comparison with the control treatment. Arbuscular mycorrhizal (AM) colonisation decreased with rock mineral fertilisation with or without microbial consortium inoculant except in cocksfoot. Conclusions: The response to microbial consortium inoculation, either alone or in combination with rock mineral fertiliser, was plant species‐dependent, indicating its potential use in pasture production.     

EFFECTS OF GYPSUM ENHANCED COMPOSTS ON YIELDS AND MINERAL COMPOSITIONS OF BROCCOLI AND TALL FESCUE

Gypsum (CaSO₄·2H₂O) addition during composting of manure or biosolids can reduce ammonia nitrogen losses and represents a new method for controlling odors. Additional work is needed, however, to test the ability of the gypsum-containing composts to support plant growth and affect uptake of nutrients and heavy metals. A field study using broccoli (Brassica oleracea L. var. italica) and a growth chamber study using tall fescue (Festuca arundinacea) were conducted by application of composts at 10 Mg ha^?1 for broccoli and 10 and 25 Mg ha^?1 for tall fescue. Compared to composts without gypsum, at 10 Mg ha^?1, gypsum composts significantly increased or had a strong trend to increase yields of broccoli and tall fescue. Gypsum composts affected concentrations of nutrient elements but did not increase concentrations of environmental concern elements in broccoli flowers and tall fescue tissue. Thus gypsum composts can be safely applied to soils to enhance crop growth.     

Effect of fertilization and harvest frequency on yield and quality of tall fescue and smooth bromegrass

Abstract

Fertilization and harvest frequency affect yield and quality of forages. The purposes of this experiment were to determine (i) the effects of fertilization and frequent harvesting on yield and quality of tall fescue (Festuca arundinacea Schreb.) and smooth bromegrass (Bromus inermis Leyss.) and (ii) the efficiency of N in animal waste as compared with inorganic N fertilizer for forage production of these cool season grasses. ‘Fawn’ tall fescue and ‘Southland’ smooth bromegrass were grown in the greenhouse on Pullman clay loam topsoil (fine, mixed thermic Torrertic Paleustoll) under eleven fertilizer treatments and two harvest regimes. Nitrogen fertilizer increased yields, N and K concentrations and K/(Ca + Mg) ratios and decreased P, Ca, and Mg concentrations. Phosphorus and K fertilizers did not affect yields but applied P increased P and tended to decrease N and Ca concentrations. Applied K tended to increase Ca concentrations. Recovery of N from feedlot manure ranged from 0.8 to 14%, whereas, recovery from NH₄NO₃ averaged 64%. Harvesting at 3‐week rather than at 6‐week intervals reduced yields 25%; however, N and P removal were higher under the 3‐week harvest regime. Even though forage production was reduced under heavy utilization, the grasses required more N fertilizer under heavy than under lighter utilization. The two grasses produced similar yields under the 3‐week cutting regime and at N rates through 340 kg/ha under the 6‐week cutting regime. Tall fescue yields were higher with the higher N rates under the 6‐week cutting regime. Smooth bromegrass forage was higher than tall fescue forage in N, K, and Ca, whereas tall fescue forage was higher in P and Mg.     

Tall fescue aluminum tolerance is affected by neotyphodium coenophialum endophyte

Roots of endophyte‐infected (E+) tall fescue (Festuca arundinacea Schreb.) exude more phenolic‐like reductants than roots of endophyte‐free (E‐) plants when mineral stressed. Phenolic compounds are efficient chelators of aluminum (Al) and may influence Al tolerance in many plant species. The objective of our study was to determine if enhanced release of phenolic compounds by roots of E+ plants contributes to Al tolerance in tall fescue. Two cloned genotypes (DN2 and DN11) of tall fescue infected with their naturally occurring fungal endophyte Neotyphodium coenophialum (Morgan‐Jones and Gams) Glenn, Bacon and Hanlin and their noninfected isolines were grown in nutrient solutions at 0 μM Al (Al‐) and at 640 μM Al (Al+) under controlled environment conditions. Root and shoot dry matter (DM) of endophyte‐infected tall fescue was greater in E+ than E‐ plants by 57% and 40%, respectively, when plants were grown without Al. Endophyte infection did not affect root and shoot DM of tall fescue grown with Al but relative (to Al‐treatment) reduction in root and shoot DM was greater in E+ than E‐ plants. In response to Al stress, more Al (47%) and P (49%) could be desorbed from root surfaces of E+ than E‐ plants. Aluminum concentrations in roots of E+ plants were 35% greater and P concentrations were 10% less than those determined in roots of E‐plants. No differences in mineral concentrations were observed in shoots, regardless of endophyte status, or Al level in nutrient solution. Roots of E+ plants increased pH of both Al‐ and Al+ nutrient solutions to a greater extent than roots of E‐ plants in a 48 h interval. Our results show that more Al can be sequestered on root surfaces and in root tissues of endophyte‐infected tall fescue than in plants devoid of endophyte. Aluminum sequestration was greater on root surfaces and in root tissues of E+ than E‐ plants of a given tall fescue genotype. Our results suggest that increased exudation of phenolic‐like compounds from roots of endophyte‐infected tall fescue may be directly involved in Al tolerance and serves as a mechanism for widespread adaptability and success of endophyte‐tall fescue associations.     

Yield and mineral concentration of HiMag compared to other tall fescue cultivars grown in the southern piedmont

HiMag is an experimental cultivar derived from Missouri 96 (Mo96) and Kentucky 31 (K31) tall fescue (Festuca arundinacea Schreb.) parentage for increased calcium (Ca), magnesium (Mg), and reduced potassium (K)/ (Ca+Mg). Our objective was to determine productivity and mineral characteristics of endophyte‐free (E‐) HiMag in relation to standard tall fescue cultivars when grown in the Southern Piedmont Land Resource Area. In experiment 1, HiMag (E‐) and K31 (E‐) were grown at two levels of phosphorus (P), K, and lime additions to both severely eroded, and non‐eroded Cecil soil (clayey, kaolinitic, thermic family of Typic Hapludults). Herbage Ca and Mg were greater and K/(Ca+ Mg) and yield were less for HiMag than for K31. Phosphorus and K concentrations were not different. Herbage yields, P, Ca, and Mg concentrations were increased by P, K, and lime additions. In experiment 2, HiMag(E‐), K31(E‐), endophyte‐infected K31(E+), Mo I(E+), Mo II (E+), and AU Triumph (E‐) were planted either in a prepared seedbed or planted without tillage into the Cecil soil. HiMag yields were not different from Mo‐I, Mo‐II or K31(E±), but were less than those of AU Triumph (E‐). HiMag yield response to no‐till planting, past soil erosion, and fertilizer level was similar to that of K31 (E±). Fertilizer level, and soil condition affected the magnitude of differences in mineral levels in HiMag and K31 (E±), but K/(Ca+Mg) values were more favorable in HiMag. All tall fescue cultivars established equally well in no‐till or prepared seedbeds. Aside from a slightly lower first harvest yield there were no important effects of planting no‐till versus planting in a prepared seedbed. HiMag's agronomic attributes, while not superior to other cultivars, were sufficient to justify further testing to improve Mg nutrition of grazing animals.     

Response of kentucky‐31 tall fescue to broiler litter and composts made from broiler litter

Abstract

Recycled paper treated with boric acid (BA) is gaining acceptance as bedding in broiler houses. Applying this litter to Kentucky 31 (K‐31) tall fescue, Festuca Arundinacea Shreb, pastures raises the issue of potential boron (B) toxicity. There is also the question of nitrogen (N) availability from composts made with borated paper and broiler manure. The effect of five N sources at 224, 448, and 896 kg N/ha in a factorial arrangement plus an unfertilized control and high nitrogen‐phosphorus‐potassium (NPK) + additional boron at 45 kg B/ha on growth and NPKB uptake of K‐31 tall fescue was determined in a greenhouse during the spring of 1992. The five N sources were (1) inorganic salts, (2) compost made from hen manure, broiler manure, fescue hay and bark (M1), (3) fresh broiler litter (M2), (4) compost made from broiler manure and borated paper bedding (M3), (5) compost from hen manure, oak leaves, broiler litter (M4). The soil was Cecil sandy clay loam subsoil. Six harvests were made at 4‐cm cutting heights for determination of dry matter, N, P, K, and B uptake in tops, stubble, roots, and residue. Relative yield response of M2 was 65% of that from inorganic NPK, whereas the yield of the three composts was 22–30% of that from inorganic NPK. Over 50% of the N applied in compost residue remained at the soil surface. Boron toxicity to K‐31 as estimated from yield reduction or from visual symptoms did not occur from 20 kg B/ha in compost made with borated paper (M3). However, a 12% yield reduction did occur at the 45 kg B/ha rate from inorganic B. Industry efforts to reduce the amount of boric acid used in the treatment of recycled paper, the high mobility of B in humid areas, the apparent ability of K‐31 tall fescue to tolerate massive quantities of compost and high rates of B application suggest that the application of the broiler litter from houses where BA‐treated recycled paper is used as bedding would be environmentally safe at application rates based on N requirements of K‐31 tall fescue.     

Responses of forage grasses to aluminum in solution culture

Growth, nutrient uptake and nutrient uptake efficiency differences in orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb), and timothy (Phleum pratense L.) were evaluated at 0, 100, 200, and 300 μM Al. In each of the species, cultivar differences were also compared. In the absence of Al stress, cultivars of orchardgrass outperformed other grasses. The presence of Al reduced shoot and root growth; however, the magnitude of the growth reduction depended upon the species and cultivars. The growth of shoots and roots showed a significant difference with respect to species, cultivars, treatment Al and their Interactions. Aluminum reduced the uptake of many essential nutrients. At 100 μM Al Potomac orchardgrass had the highest and climax timothy had the lowest mineral content. The efficiency ratio (ER) assisted in classifying grass entries into efficient and inefficient utilizers of the absorbed nutrients. The ER is defined as milligrams of dry shoot weight produced per milligram of element in the shoot. The ER for P, K, Cu and Zn gave a positive correlation with shoot weight; however, in general, negative relationships were observed for shoot growth and ER for Mg, Fe, and Mn. In all the species increasing Al concentration from 0 to 100 μM increased ER for Mg and decreased ER for K and Zn. With the exception of tall fescue cultivars, the ER for P was reduced by 100 μM Al. The species and cultivars used in this study showed inter‐ and intraspecific differences in growth, uptake, and ER for nutrients in the presence or absence of Al stress. Significant reduction in growth, even at 100 μM Al by all the three species of grass indicates that these grass species are far more sensitive to Al than the field crops. Therefore, experiments with levels of Al lesser than 100 μM would have given a better outlook on the performances of these grass species.     

The use of carbonatite rock powder as a liming agent

Carbonatite rock powder, originating from the Lillebukt Alkaline Complex at Stjernøy in northern Norway, can potentially be used as a slow‐releasing lime and potassium (K) and magnesium (Mg) fertilizer due to a high concentration of the easily weathered minerals calcite (42%) and biotite (30%). However, the enrichment of barium (Ba) and strontium (Sr) may cause an undesired uptake to plants when carbonatite is applied to agroecosystems. A pot experiment was designed to investigate the liming and fertilization effects of carbonatite and the potential mobilization of Ba and Sr compared to a dolomite lime commonly used in Norwegian agriculture. These liming agents were mixed with a sandy soil applied to different amounts of peat, and the uptake of Ba, Sr, calcium (Ca), Mg, and K by Festuca arundinácea Schreb. Kora (tall fescue) and Trifolium repens L. Milkanova (white clover) was evaluated. The liming agents were generally incapable of buffering the acidifying effect from increased applications of peat, while the plant dry mass was unaffected. Compared to pots given dolomite and soluble K, the availability of K from carbonatite to plants was equally high or higher, and no difference in the K:(Ca + Mg) ratio in plants was observed. Carbonatite was a significant source to plant Ba and Sr, and the uptake seemed to follow the Ca uptake. Addition of peat amplified the uptake of Ba, Sr, Ca, Mg, and K to plants, probably an effect of organic acid‐induced weathering of carbonatite. White clover took up Ba, Sr, and Ca more effectively than tall fescue, but the Ba and Sr concentrations in plants were relatively moderate compared to concentrations reported from field investigations.     

Influence of temperature on nutrient concentration and tetany potential of hardinggrass and tall fescue

Grass tetany (Hypomagnesemia) potential of TAM Wintergreen Hardinggrass and 16 tall fescue lines and varieties was estimated by determining the K, Ca and Mg concentrations in the herbage and the ratio of K/(Ca + Mg) (milliequivalent basis). Data were obtained at four dates during a two‐year period to determine the environmental conditions under which selections should be made to achieve the greatest progress in decreasing the tetany potential of tall fescue and to determine if either of the grasses have high tetany potential in the North Texas area. Hardinggrass had a greater potential to produce grass tetany than tall fescue when grown on the Northern Blackland Prairie of Texas. There were significant differences in K, Ca and Mg concentrations and K/(Ca + Mg) ratio among dates and tall fescue lines. The average temperature for the 30 days before harvest was related to the mineral content and to the K/(Ca + Mg) ratio in all varieties. The K(Ca + Mg) ratio was highest at approximately 18°C but the Mg content fell below the 0.18% required for lactating beef cows when the average temperature for the 30 days before harvest was 22.4°C. Progress could be made in breeding for low grass tetany proneness but selections should be made over a wide range of temperatures considering both the Mg content and ratio of K/(Ca + Mg).     

Shoot growth,plant tissue elemental composition,and soil salinity following irrigation of alfalfa and tall fescue with high‐sulfate waters 1

Groundwater contaminated with sulfate (SO₄ ^2‐) at concentrations higher than allowable for drinking water might still be usable for irrigation. Objectives were to determine the growth response and mineral uptake of two forage crops irrigated with waters containing SO₄ ^2‐ at concentrations ranging from 175 to 1743 mg/L, and with electrical conductivities (EC) ranging from 1.2 to 3.6 dS/m. Plants were grown for 12 weeks in 8‐L pots containing a calcareous sandy loam and were harvested at 4, 8, or 12 weeks for plant growth measurements and tissue analysis. Digested leaves, stems, and reproductive tissues were analyzed by inductively coupled plasma (ICP) spectroscopy at each harvest, as were saturated soil paste extracts. Shoot growth of tall fescue (Festuca arundinacea Schreb.) was not affected by irrigation water treatment, whereas shoot growth of alfalfa (Medicago sativa L.) was increased by a moderate level of soil solution SO₄ ^2‐ Sulfur (S), boron (B), magnesium (Mg), sodium (Na), and zinc (Zn) concentrations in shoot tissues of both species showed a tendency to increase with increasing SO₄ ^2‐ content of irrigation water. Shoot tissue concentration of molybdenum (Mo) increased with maturation in both species, while the concentrations of B, potassium (K), manganese (Mn), Na, and Zn decreased. Soil saturated paste extract concentrations of Mg and Na increased with irrigation water Mg and Na concentrations, while Ca and S concentrations in the soil solution became saturated at the higher irrigation water concentrations of these elements.     

Effects of aluminium on growth and nutrition in birch seedlings under magnesium- or calcium-limiting growth conditions

Growth and nutrition of birch seedlings (Betula pendula Roth) with and without 0.5 mM Al³⁺ were studied. The seedlings were cultivated at growth-limiting Mg- or Ca-conditions by adding one of these elements at relative addition rates (R_Mg, R_Ca) of 0.15 day^?1. The concentration of Ca²⁺ in the Mg-limited treatments was 0.01.0.1 or 1 mM and Mg²⁺ was given in equal molarities in the Ca-limited treatments. The relative growth rates, R_G, of the plants and plant parts attained values close to R_Mg or R_Ca and were not affected by the concentration of Ca²⁺, Mg²⁺ or Al³⁺ in the culture solution. Uptake of Ca, at Ca-limitation, increased significantly in the roots after addition of Al, and decreased in all plant parts when the Mg concentration of the culture solution was raised. Less clear effects were found on Mg uptake at Mg-limitation. The inhibitory effect of Al on Mg uptake decreased with time as a result of the growth technique. The root mass fraction was significantly larger in plants limited in Ca (24%) than in plants limited in Mg (20%). The usefulness in using the balance between Ca and Al or ratios between Ca, Mg, K and Al as diagnostic tools for assessing the nutritional status of trees is discussed.     

Growth and Nutrient Use in Four Grasses Under Drought Stress as Mediated by Silicon Fertilizers

Field water stress is a common problem in crop production, especially in arid and semi-arid zones and it is widely hypothesized that silicon (Si) could reduce water stress in plants. We set up a greenhouse study to evaluate some silicon sources—potassium silicate (K₂SiO₃), calcium silicate (CaSiO₃) and silica gel for growth and nutrient uptake by four grass species under adequate and deficit irrigation. The four species studied were Rhodes grass (Chloris gayana), Timothy grass (Phleum pratense), Sudan grass (Sorghum sudanense) and Tall fescue (Festuca arundinacea). For all species, the biomass yield response to applied silicon under deficit irrigation was significantly better than under adequate irrigation. The yield response of Rhodes grass across silicon sources was 205% under deficit irrigation compared with only 59% under adequate irrigation; for Sudan grass it was 49% compared with 26% and for Timothy, it was 48% compared with a mere 1%. The higher responses under deficit irrigation suggest that the plants relied more on silicon to endure drought stress. Biomass yield of individual plants also differed according to soil water levels with Timothy grass being the most sensitive to water stress as it exhibited the highest yield response (209%) to adequate irrigation. This was followed by tall fescue (122%) and Rhodes grass (97%). Sudan grass was the least affected by deficit irrigation, possibly on account of improved root mass and its natural drought tolerance. Strong associations were noted between the uptake of silicon and those of nitrogen (N) and phosphorus (P) irrespective of soil water condition, but the uptake of potassium (K) was more strongly correlated with that of Si under deficit than adequate irrigation. Improvements in plant growth following Si application could therefore be linked to enhanced uptake of major essential nutrients.     

Neotyphodium endophytes trigger salt resistance in tall and meadow fescues

Infection with Neotyphodium spp. endophytes increases resistance to drought stress and soil mineral imbalances in tall fescue (Festuca arundinacea Schreb. = Lolium arundinaceum (Schreb.) S. J. Darbysh.) and meadow fescue (Festuca pratensis Huds. = Lolium pratense (Huds.) Darbysh.). We hypothesized that resistance of these grasses to salinity stress may also be attributed to endophyte infection. Two tall fescue genotypes, Fa75 and Fa83, and one meadow fescue genotype, Fp60, infected (E+) with their endophytic fungi, Neotyphodium coenophialum (Glenn, Bacon and Hanlin) and N. uncinatum (Glenn, Bacon and Hanlin), respectively, and their noninfected counterparts (E–) were cultured in nutrient solution at three salinity levels of 0, 85, and 170 mM NaCl. Except for genotype Fa75, E+ plants exhibited higher leaf survival rates than E– clones at a high salinity level (170 mM). Root dry matter was higher in E+ than in E– plants, but shoot dry matter was not affected by endophyte infection. This resulted in a lower shoot‐to‐root ratio in E+ plants (1.63) compared with E– plants (2.40). Sodium (Na⁺) and chloride (Cl^–) concentrations were greater in roots of E– than in E+ clones. In shoots, Na⁺ and Cl^– concentrations were not affected by the endophyte. In contrast, E+ plants accumulated more potassium (K⁺), which resulted in a greater K⁺ : Na⁺ ratio in shoots of E+ than in those of E– plants. Our results show that endophyte infection reduced Na⁺ and Cl^– concentrations in tall fescue and meadow fescue roots but increased K⁺ concentrations in the shoots. Based on these results, we conclude that endophyte‐infected grasses may thrive better in salinity‐stress environments.     

Simulating NaCl accumulation in a closed hydroponic crop of zucchini: Impact on macronutrient uptake,growth, yield,and photosynthesis

Zucchini squash (Cucurbita pepo L.) plants were grown in a closed‐loop hydroponic system and supplied with nutrient solution (NS) containing NaCl at different concentrations (0.7, 3, 5, and 7 mM). The primary aim of the study was to define the relationship between the concentration of Na⁺ and Cl⁻ in the root zone solution and the respective Na⁺/water or Cl⁻/water uptake ratios (uptake concentrations, UC). A second objective was to determine the UC of macronutrients (i.e ., N, P, K, Ca, and Mg) and to test whether they are influenced by the gradual increase of the root zone salinity due to progressive NaCl accumulation. Two experiments were conducted, of which one (spring crop) was used to parameterize an existing empirical model, while the second one (autumn‐winter crop) was commissioned to test the validity of the determined model parameters. Both Cl⁻ and Na⁺ ions accumulated progressively in the root zone solution over time, showing a tendency to stabilize at final concentrations according to the corresponding NaCl treatment. The relationship between the Na⁺ and Cl⁻ concentrations in the root zone and the Na⁺/water or Cl⁻/water uptake ratios was exponential and the model parameters successfully fitted to data from crops cultivated in different growth seasons. This model may be used to monitor Na⁺ and Cl⁻ concentrations in the root environment of zucchini crops as relationships of the plant water consumption. The exposure of plants to NaCl affected the UC of N, K, Ca, and Mg, but the results for some nutrients were not consistent in both growth seasons. The measurements of plant growth characteristics (i.e ., biomass, yield, fruit quality, and photosynthesis) revealed that water resources containing up to 3 mM NaCl do not cause unacceptable yield losses in zucchini crops grown in completely closed hydroponic systems.     

An extended nitrogen,phosphorus, and potassium model for tall fescue

Abstract

Dry matter yields and plant nutrient uptake of forage grasses are influenced by levels of applied nitrogen (N), phosphorus (P), and potassium (K). Response to one element generally depends on levels of the other two. In this article, a mathematical model is presented which includes the major elements, N, P, and K as inputs. It consists of triple logistic equations with a total of thirteen parameters. The model is evaluated for Kentucky 31 (KY 31) and Kenwell tall fescue (Festuca arundinacea Schreb.) grown at Watkinsville, GA on Cecil sandy loam (clayey, kaolinitic, thermic, Typic Hapludult). Procedures are described for parameter estimation. The model provides high correlation between yields and plant uptake of N, P, and K with applied N, P, and K for both cultivars of tall fescue, as demonstrated in response graphs and scatter diagrams. Intercept and N response coefficients from this study agree closely with those from previous work. Data from this study support the hyperbolic relationship between dry matter yield and plant N uptake predicted by the model. The model is mathematically well‐behaved and is relatively easy to use in practice.     

Phytoextraction of Zinc by Indian Mustard and Tall Fescue

Abstract

This experiment evaluated the capacity of two species, Indian mustard (Brassica juncea Czern.) and tall fescue (Festuca arundinacea Schreb.) to extract zinc (Zn) from soils. Also, this experiment focused on using nitrogen (N) fertilizers to increase the phytoextraction of Zn. Two soils of the Hadley series (Typic Udifluvents) were studied. A treatment array of Zn concentrations in soils was supplied as zinc sulfate. Nitrogen was supplied at 200 mg N/kg of soil as calcium nitrate, urea, or compost. Two successive plantings of Indian mustard in the same media were grown until flowering and harvested. Fescue was grown from seeding to a height of 15 cm, harvested, grown again in the same media to a height of 15 cm, and harvested again. After the second harvests of Indian mustard and fescue, soil samples were taken for analysis of extracts with water and with Morgan's solution. Indian mustard was grown with Zn additions ranging from 0 to 100 mg/kg soil. The shoot mass of Indian mustard in both harvests increased to a soil‐Zn level of 25 mg/kg and then decreased. Although growth decreased as the soil‐Zn levels increased beyond 25 mg/kg, Zn concentration and total accumulation increased linearly as the soil‐Zn levels increased. Zinc concentration and accumulation in Indian mustard were highest in soils amended with urea and were lowest in soils with no fertilizer. Fescue was grown with Zn additions ranging from 0 to 1000 mg/kg soil. The shoot mass of fescue increased to a soil‐Zn level of 125 mg/kg (harvest 1) or 250 mg/kg (harvest 2) and then decreased as the soil‐Zn levels increased. Concentration and accumulation of Zn in fescue increased linearly as the soil‐Zn levels increased. Zinc concentration and accumulation were highest in fescue grown in soils amended with urea and lowest in soils with no fertilizer. The highest accumulation of Zn in fescue (3800 mg/pot) occurred at 1000 mg Zn/kg soil. Highest concentrations of soil Zn were extracted with Morgan's solution or water from soils amended with urea, regardless of the species grown in the soils. Lowest concentrations of Zn were extracted from soils with no fertilizer added, regardless of extract or species. In general, if fertilizers (calcium nitrate, urea, or compost) were added to the soils, the pH decreased. Fescue was easy to grow, tolerated much higher soil‐Zn levels than Indian mustard in this research, and could be a species useful for phytoextraction of Zn.     

不同氮素形态对干旱胁迫杉木幼苗养分吸收及分配的影响

【目的】干旱胁迫是限制植物生长的重要非生物因素之一,而适宜的氮素营养可以提高植物的抗旱性。本文探讨了供应不同形态氮源对干旱条件下杉木[Cunninghamia lanceolata (Lamb.) Hook]幼苗养分吸收及分配的影响。【方法】采用水培试验,供试杉木材料为2个无性系幼苗(7–14号和8–8号),在营养液中添加10%(w/v)PEG-6000进行干旱胁迫。营养液中的氮源处理包括硝态氮、铵态氮、硝铵混合氮,氮素浓度均为4.571mmol/L,每个品种均设6个处理。培养20天后,测定了杉木幼苗根、茎、叶的养分含量及生物量。【结果】与正常水分供应相比较,干旱胁迫条件下供应铵态氮可促进叶片N、K以及茎叶P、K的吸收,供应混合氮可促进根部K的吸收;供应铵态氮可促进根、茎对Ca的吸收,对叶片Ca无明显作用。干旱胁迫对根部Fe、Mn、Cu、Zn吸收量影响显著,氮素供应不同程度地降低了干旱胁迫下各器官Mg、Fe、Mn和Cu吸收量,表现为抑制吸收,但添加铵态氮比硝态氮的降低幅度小。3个氮源处理均降低了干旱条件下根部Zn吸收量,但没有降低甚至增加了茎、叶中Zn的吸收量,说明氮营养可调节Zn在各器官间的分配,缓解干旱导致的缺锌现象。不同器官之间各养分吸收量差异显著,3个氮源处理中,N和P吸收量表现为叶>根>茎,K和Ca为叶>茎>根,Fe、Cu为根>叶>茎,Mg、Mn和Zn在各器官之间的分配规律不一。铵态氮吸收量均表现为叶>根>茎,且各器官铵态氮吸收量显著高于硝态氮,说明杉木具有明显的喜铵特性。【结论】在干旱胁迫下,氮素供应形态显著影响杉木幼苗对养分的吸收及在各器官中的分配,作用效果因家系品种和元素种类而异。总体来讲,铵态氮提高干旱胁迫下杉木幼苗养分吸收的效果好于硝态氮,杉木可以认为是喜铵植物。