Starter fertilizer to spring barley and spring wheat in south-east Norway: Effects on growth and nutrient uptake

Abstract

Field experiments were carried out on three representative soils, to evaluate the effect of various starter fertilizers, together with different rates of band placed phosphorus (P), on nutrient uptake and yield of spring barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.). The starter fertilizers were placed in the immediate vicinity of the seed, while the band placed P was placed at about 5 cm below the seeds and spaced at 25 cm between alternate seed rows. As starter fertilizer, monoammonium phosphate (MAP), calcium nitrate (CAN), ammonium nitrate (AN) and triple superphosphate (P20) were compared. In both species, effects of starter fertilizer on P uptake were most marked early in the growing season. At GS 13 application of 20 kg P ha^?1 as MAP increased the P uptake by 50% in barley and by 35% in wheat, compared to no seed-placed nutrients. For grain, the increase in P content was 8% for both species. The higher P uptake at GS 13 was supported by observations of higher plant vigour in the treatments with either P20 or MAP as starter fertilizer. The use of N only as starter fertilizer did not increase the vigour of the plants. Band placement of P also gave more vigorous plants in spring barley. The grain yield increased on the silty clay loam and on the silt soil when starter fertilizer was applied, especially with the use of MAP. Smaller and non-significant yield differences were found when starter fertilizer was used on the loam soil. No delay or reduction of emergence was observed with starter fertilizer. Therefore, on soils where root growth or nutrient uptake becomes limited during the first weeks after sowing, application of starter fertilizer is recommended in Norway for both spring barley and spring wheat. Crops grown on silty soils seem to have an especially high demand for easily available P given as starter fertilizer.     

Potassium efficiency mechanisms of wheat,barley, and sugar beet grown on a K fixing soil under controlled conditions

Plant species differ in their potassium (K) efficiency, but the mechanisms are not clearly documented and understood. Therefore, K efficiency of spring wheat, spring barley, and sugar beet was studied under controlled conditions on a K fixing sandy clay loam. The effect of four K concentrations in soil solution ranging from low (5 and 20 μM K) to high (2.65 and 10 mM K) on plant growth and K uptake was investigated at 3 harvest dates (14, 21, and 31 days after sowing). The following parameters were determined: shoot dry matter (DM), K concentration in shoot dry matter, root length (RL), root length/shoot weight ratio (RSR), shoot growth rate/average root length ratio (GR_s/aRL), K influx, and soil solution K concentrations. Wheat proved to have a higher agronomic K efficiency than barley and sugar beet, indicated by a greater relative yield under K‐deficient conditions. As compared to both cereals, sugar beet was characterized by higher K concentrations in the shoot dry matter, only 30—50 % of the root length, 15—30 % of the RSR and a 3 to 6 times higher GR_s/aRL. This means that the shoot of sugar beet had a 3 to 6 times higher K demand per unit root length. Even at low K concentrations in the soil solution, sugar beet had a 7 to 10 times higher K influx than the cereals, indicating that sugar beet was more effective in removing low available soil K. Wheat and barley were characterized by slow shoot growth, low internal K requirement, i.e. high K utilization efficiency, and high RSR, resulting in a low K demand per unit root length. At low soil K concentrations, both cereals increased K influx with age, an indication of adaptation to K deficiency. The mechanism of this adaptation merits closer investigation. Model calculations were performed to estimate the K concentration difference between the bulk soil and the root surface (ΔC_L) needed to drive the measured K influx. For the two cereals, the calculated ΔC_L was smaller than the K concentration in the soil solution, but for sugar beet, ΔC_L was up to seven times higher. This indicates that sugar beet was able to mobilize K in the rhizosphere, but the mechanisms responsible for this mobilization remain to be studied.     

Responses of barley to hypoxia and salinity during seed germination,nutrient uptake,and early plant growth in solution culture

The resistance of most plants to salt can be impaired by concurrent waterlogging. However, few studies have examined this interaction during germination and early seedling growth and its implications for nutrient uptake. The aim of the study was to examine the response of germination, early growth, and nutrient uptake to salt (NaCl) and hypoxia applied to barley (Hordeum vulgare L. cv. Stirling), in solution culture. Hypoxia, induced by covering seeds with water, lowered the germination from 94% to 28% but salinity and hypoxia together lowered it further to 13% at 120 mM NaCl. While the germination was 75% at 250 mM NaCl in aerated solution, it was completely inhibited at this NaCl concentration under hypoxia. Sodium ion (Na⁺) concentrations in germinated seedlings increased with increasing salinity under both aerated and hypoxic conditions during germination, while K⁺ and Mg⁺ concentrations were decreased with increasing salinity in 6 d old seedlings. After 20 d, control seedlings had the same dry weights of the roots and shoots with and without hypoxia but at 10 mM NaCl and higher, shoot and root dry weight was depressed with hypoxia. Sodium ion increased in roots and shoots with increased NaCl under both aerated and hypoxic conditions while K⁺ was depressed when salinity and hypoxia were applied together and Ca²⁺ was mostly decreased by NaCl. In general, hypoxia had greater effects on nutrient concentrations than NaCl by decreasing N, P, S, Mg, Mn, Zn, and Fe in shoots and by increasing B concentrations. The threshold salinity levels decreased markedly for germination, uptake of a range of nutrients, and for seedling growth of barley under hypoxic compared to well‐aerated conditions.     

Effects of Fe compounds on nutrient uptake by plants grown in sand media with different pH

The effect of soil and foliar application of different iron (Fe) compounds (FeSO₄, Fe‐EDTA, Fe‐EDDS, and Fe‐EDDHA) on nutrient concentrations in lettuce (Lactuca sativa cv. Australian gelber) and ryegrass (Lolium perenne cv. Prego) was investigated in a greenhouse pot experiment using quartz sand as growth medium. Soil application was performed in both the acidic and alkaline pH range, and foliar application to plants grown in the alkaline sand only. Lettuce growth was depressed by Fe deficiency in the alkaline sand, whereas the treatments had no effect on ryegrass growth. Soil‐applied Fe compounds raised the Fe concentrations in lettuce. This was especially true for the Fe chelates, which also increased yields. Soil‐applied Fe compounds had no statistically significant effect on Fe concentrations in ryegrass. Concentrations of manganese (Mn) in lettuce were equally decreased by all soil‐applied chelates. In the alkaline sand, soil application of Fe‐EDDHA elevated copper (Cu) and depressed zinc (Zn) concentrations in lettuce. The chelates increased Zn concentration in ryegrass. Foliar application of Fe‐EDDS increased Fe concentrations in lettuce and in ryegrass most. Fe‐EDDHA depressed Mn and Zn concentrations in lettuce more than other Fe compounds, suggesting the existence of another mechanism, in addition to Fe, that transmits a corresponding signal from shoot to roots with an impact on uptake of micronutrients.     

Effects of NPK source on the dry matter partitioning in cool season C3-cereals (wheat,rye, barley,and oats) at various growth stages

Dry matter (DM) partitioning into root, leaf, stem, shoot dry weight plant^?1 response in four cool season C₃-cereals viz. wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.) and oats (Avena sativa L.) was investigated at 30, 60 and 90 days after emergence (DAE) under eight nitrogen, phosphorus and potassium (NPK) sources: S₁ = 20-20-20, S₂ = 20-27-5, S₃ = 7-22-8, S₄ = 10-10-10-20S, S₅ = 11-15-11, S₆ = 31-11-11, S₇ = 24-8-16, and S₈ = 19-6-12 in pot experiment at Dryland Agriculture Institute, West Texas A&;M University, Canyon, Texas, USA during winter 2009-10. A considerable variation in DM partitioning into various plant parts was observed in the four crop species at different growth stages and NPK source. At 30 DAE, 27% of the total DM per plant (TDMPP) was partitioned into roots and 73% into shoots (19% stems + 54% leaf). Only16 % of the TDMPP was partitioned into roots and 84% into shoots (18 % stem + 66 % leaf) at 60 DAE. At 90 DAE, 29% of TDMPP was partitioned into roots and 71 % into shoots (33 % stems + 38 % leaf) at 90 DAE. Percent DM partitioning into stems ranked first (33%) at 90 DAE > at 30 DAE (19%) > at 60 DAE (18 %). With advancement in crops age, DM partitioning into various crop parts increased. The root DM plant^?1 (RDMPP) increased from 11.5–722 mg plant^?1; stem DM plant^?1 (STDMPP) from 8.3–889.0 mg plant^?1; leaf DM plant^?1 (LDMPP) from 23.1–1031.0 mg plant^?1; shoot DM plant^?1 (SHDMPP) from 31.3–1921 mg plant^?1, and TDMPP increased from 42.9–2693.0 mg plant^?1 at 30 and 90 DAE, respectively. Because of the higher N contents in S₇ (24:8:16) and S₆ (31:11:11) reduced the DM partitioning into various plants parts as well as TDMPP at all three growth stages. The adverse effects of S₆ and S₇ on DM partitioning was more on oats > rye > wheat > barley. The S₄ with 10:10:10 (NPK) and :20S was not toxic at 30 DAE, but at 60 and 90 DAE it became toxic that adversely affected the DM partitioning as well as TDMPP probably may be due its high sulfur (20%) content which lacking in other NPK sources. The DM partitioning to various parts of barley and wheat was more than oats and rye at different growth stages (barley > wheat > rye > oats). Since the DM portioning values were determined on the average of five plants in pot experiment under organic soil at field capacity; in case of field experiments more research is needed on various crop species/varieties under different environmental conditions particularly under moisture stress condition.     

Alleviation of drought stress in winter wheat by late foliar application of zinc,boron, and manganese

In many regions, drought during flowering and grain‐filling inhibits micronutrient acquisition by roots resulting in yield losses and low micronutrient concentrations in cereal grains. A field and a greenhouse experiment were conducted to study the effect of foliar applications of zinc (Zn), boron (B), and manganese (Mn) at late growth stages of winter wheat (Triticum aestivum L.) grown with or without drought stress from booting to maturity. Foliar applications of Zn, B, and Mn did not affect grain yield in the absence of drought. However, under drought, foliar application of Zn and B in the field increased grain yield (15% and 19%, respectively) as well as raising grain Zn and B concentration, while Zn and Mn sprays in the greenhouse increased grain yield (13% and 10%, respectively), and also increased grain Zn and Mn concentrations. Furthermore, under drought stress both in the field and greenhouse experiment the rate of photosynthesis, pollen viability, number of fertile spikes, number of grains per spike, and particularly water‐use efficiency (WUE) were increased by late foliar application of micronutrients. These results indicate that by increasing WUE foliar application of Zn, B, and Mn at booting to anthesis can reduce the harmful effects of drought stress that often occur during the late stages of winter wheat production. These findings therefore are of high relevance for farmers' practice, the extension service, and fertilizer industry.     

Micronutrient deficiencies and toxicities of cassava plants grown in nutrient solutions. I. Critical tissue concentrations

The programmed nutrient addition technique was used in a series of 5 experiments to determine the response in growth and micronutrient content of cassava (Manihot esaulenta Crantz) cv. M Aus 10, to 8 supply levels of boron, copper, iron, manganese and zinc respectively. The experiments were of 9 weeks duration and utilized 22 litre pots of nutrient solution. The supply levels for each micronutrient covered the range from severe deficiency to toxicity. Critical tissue concentrations for deficiencies determined by relating total dry matter production to the nutrient concentration in the youngest fully expanded leaf blades were (μg/g): boron 35, copper 6, manganese 50, and zinc 30. Likewise, critical concentrations for toxicities in the same index tissue were (μg/g): boron 100, copper 15, manganese 250, and zinc 120. In the iron experiment, the data were too variable to allow precise determination of critical concentrations for deficiency and toxicity. Critical micronutrient concentrations in the petioles of the youngest fully expanded leaves were also determined, but offered no advantage over the leaf blades.     

Effects of zinc activity in nutrient solution on uptake,translocation, and root export of cadmium and zinc in three wheat genotypes with different zinc efficiencies

The interactions of zinc (Zn) and cadmium (Cd) in uptake and translocation are common but not consistent. We hypothesized that Cd²⁺ and Zn²⁺ activity in the apoplasmic solution bathing root-cells could affect Zn accumulation in plants dependent on the wheat genotype. This hypothesis was tested using seedlings of two bread wheat genotypes (Triticum aestivum L. cvs. Rushan and Cross) and one durum wheat genotype (Triticum durum L. cv. Arya) with different Zn efficiencies grown in chelate-buffered nutrient solutions with three Zn²⁺ (10^?11.11, 10^?9.11, and 10^?8.81?µM) and two Cd²⁺ (10^?11.21 and 10^?10.2?µM) activity levels. Increasing Zn²⁺ activity in the nutrient solution significantly increased Zn concentration in root and shoots of all three wheat genotypes, although the magnitude of this increase was dependent on the genotype. Cadmium decreased Zn concentration in roots of “Cross” while it had no significant effect on root Zn concentration in “Rushan.” At Zn^2+?=?10^?11.11?µM, Cd decreased shoot Zn concentration in “Arya” whereas it increased shoot Zn concentration at Zn^2+?=?10^?8.81?µM. Cadmium increased shoot Zn concentration of “Rushan” and “Cross” at Zn^2+?=?10^?8.81?µM but it had no significant effect on shoot Zn concentration of these genotypes at Zn^2+?=?10^?11.11?µM. The zinc-inefficient genotype “Arya” accumulated significantly more Cd in its root in comparison with “Cross” and “Rushan.” Cadmium concentration in roots of “Arya” was decreased significantly with increasing Zn activity. The effect of Zn on accumulation of Cd in roots of “Cross” and “Rushan” was dependent on the dose provided, and therefore, both synergistic (at Zn^2+?=?10^?9.11?µM) and antagonistic (at Zn^2+?=?10^?8.81?µM) interactive effects were found in these genotypes. Zinc supply increased the Zn concentration of xylem sap in “Cross” and “Rushan” whereas Zn content in xylem sap of “Arya” was decreased at Zn^2+?=?10^?9.11?µM and thereafter increased at Zn^2+?=?10^?8.81?µM. Cadmium treatment reduced Zn concentration in xylem sap of “Arya,” while it tended to increase Zn content in xylem sap of “Cross.” At Zn-deficient conditions, greater retention of Zn in root cell walls of Zn-inefficient “Arya” resulted in lower root-to-shoot transport of Zn in this genotype. Results revealed that the effect of Cd on the root-to-shoot translocation of Zn via the xylem is dependent on wheat genotype and Zn activity in the nutrient solution.     

The effect of Ca and K levels on the herbage yield and nutrient composition of barley plants grown in high Mg soils

Abstract

The effects of Ca and K levels on barley (cv. Johnston) yield were studied in soil media containing high levels of Mg. The dry matter yield of barley decreased with increasing concentrations of Mg in soils, but the decrease was small. Dry matter yield was positively related to concentration of K in the soil. However, additions of fertilizer Ca or K did not increase dry matter yield, indicating that depressed yield associated with high Mg levels was not due to reduced availability of Ca or K. In commercial agriculture, applications of either Ca or K to such soils are unlikely to prove beneficial in increasing crop yields.

Concentrations of Mg in soil solutions of unfertilized soils were lower than levels which were previously shown to reduce crop yield. Additions of N fertilizer increased Mg concentrations to levels which could reduce barley yield     

The role of root plasma membrane ATPase and rhizosphere acidification in zinc uptake by two different Zn-deficiency-tolerant wheat cultivars in response to zinc and histidine availability

ABSTRACT

We investigated the effect of histidine (His) and Zn deficiency on H⁺-ATPase activity and H⁺ release from wheat roots. Two bread wheat (Triticum aestivum L. cvs. Kavir and Back Cross Roshan) were grown in a nutrient solution for four weeks before being transferred to treatment solutions consisting of two concentrations of His (0 and 50 µM) and two concentrations of Zn (0 and 10 μM). The Zn-only and the Zn+His treatments were observed to release more H⁺ in the root media than did the control ones, with the highest achieved under the Zn+His treatment which was roughly 2.1 times higher than that under the control conditions. The H⁺ release from wheat roots increased slightly but significantly in the presence of only His when compared with the control solutions. The hydrolytic and transport activities of H⁺-ATPase were affected by both Zn deficiency and His supply. In both cultivars, application of Zn and His resulted in a higher hydrolytic activity of H⁺-ATPase when compared with the control solutions. The highest hydrolytic activity of H⁺-ATPase in the root plasma membrane vesicles was achieved with the Zn+His treatment. The ‘Back Cross Roshan’ exhibited a higher (PM) H⁺-ATPase activity and H⁺ pumping than did ‘Kavir’.     

Effect of organic amendments on uptake of selenium and biochemical grain composition of wheat and rape grown on seleniferous soils in northwestern India

Crops grown in seleniferous soil may accumulate selenium (Se) to levels considered highly toxic for animal and human consumption. Furthermore, higher Se content in plant tissues leads to considerable deterioration in product quality. Application of organic amendments plays an important role in improving soil physical, chemical, and biological conditions and influencing nutrient availability. A field trial was conducted to evaluate the effect of organic amendments, namely poultry manure (PM), sugar cane press mud (SCPM), and farmyard manure (FYM), on Se uptake and grain quality of wheat and oilseed rape grown on a seleniferous soil in Punjab, India. Selenium accumulation by wheat and oilseed rape grains decreased significantly (75%–95%) with the application of PM and SCPM, while FYM application resulted in a significant decrease (23%) only in case of wheat grains. The amount of Se associated with seed proteins varied in proportion to its uptake under different treatments. Quality of wheat grains improved considerably with respect to total soluble sugars, reducing sugars, starch, lipids, and sulfur concentrations only after application of SCPM and PM. Treating a Se‐contaminated soil with organic amendments significantly increased the oil concentration and changed the proportion of various fatty acids in rape grains. It is concluded that applying organic amendments to Se‐contaminated soils can alleviate the deleterious effects of Se and restore the nutritional quality of grains.     

Zinc nutrition effect on the tolerance of wheat genotypes to Fusarium root-rot disease in a solution culture experiment

Abstract

Zinc (Zn) nutrition and plant genotype are two factors that may affect the tolerance of wheat to root-rot diseases. The aim of the present study was to determine the effect of Zn on shoot yield, root permeability and infection by Fusarium solani in six wheat genotypes with different Zn efficiency. A greenhouse (solution culture) experiment was carried out in which five bread wheat genotypes (Triticum aestivum L. cvs Rushan, Kavir, Cross, Pishtaz and Falat) and one durum wheat genotype (Triticum durum L. cv. Yav79), which are common in Zn-deficient soils of Iran and were exposed to two levels of Zn (0 and 1?μmol?L^–1?Zn?kg^?1, as ZnSO₄.7H₂O) and two F. solani infection levels (0 and 10⁶?spore?mL^?1). Zinc deficiency significantly decreased shoot dry matter in five of the genotypes (Yav79, Kavir, Rushan, Cross and Falat), but had no effect on shoot growth in Pishtaz. Infection with F. solani significantly decreased the shoot dry matter in Yav79, but did not affect the shoot dry weight of the other wheat genotypes. Root membrane permeability was lower in the Zn treatments than in the Zn-free treatments. Zinc deficiency caused a decrease in root reactive sulfhydryl (SH) groups, particularly in the Cross genotype. Root sulfhydryl groups decreased with Fusarium infection. Zinc application sharply increased the Zn content and decreased the Mn content of the shoots. Application of Zn had a positive effect on the tolerance of wheat to F. solani root rot. The relationship between Zn nutrition and disease tolerance suggests that Zn deficiency should be treated before evaluating the cost-effectiveness of fungicides. No correlation was found between the Zn efficiency of the wheat genotypes and Fusarium root-rot disease severity in this solution culture experiment.     

Effect of one phosphorus rate placed in different soil volumes on p uptake and growth of wheat

Abstract

The volume of soil treated with P fertilizer affects P uptake by the crop. Earlier studies have shown that the stimulation of root growth in P‐fertilized soil was similar for both corn (Zea mays L.) and soybean (Glycine max L. Merr). The objective of this research was to determine the effect of fertilizer P placement on P uptake and shoot and root growth of spring wheat (Triticum vulgare L.). Wheat was grown for 34 days in Raub silt loam (Aquic Argiudolls) in a controlled climate chamber. One rate of phosphate per pot, 150 mg P per three kg of soil, was mixed with 2, 5, 10, 20, 40 and 100% of the soil in the pot. The P was equilibrated with moist soil for 5 days at 70°C followed by 21 days at 25° C before transplanting 8‐day‐old wheat plants into each 3 L pot. The P stimulation of root growth in the P‐treated soil was similar to that for corn and soybeans. The effect could be described by the equation y = x^0.7 where y is the fraction of the root system in the P‐fertilized soil where P is mixed with x fraction of the soil. The greatest P uptake and plant growth occurred when added P was mixed with 20% of the soil.     

Effect of zinc‐biofortified seeds on grain yield of wheat,rice, and common bean grown in six countries

Seeds enriched with zinc (Zn) are ususally associated with better germination, more vigorous seedlings and higher yields. However, agronomic benefits of high‐Zn seeds were not studied under diverse agro‐climatic field conditions. This study investigated effects of low‐Zn and high‐Zn seeds (biofortified by foliar Zn fertilization of maternal plants under field conditions) of wheat (Tritcum aestivum L.), rice (Oryza sativa L.), and common bean (Phaseolus vulgaris L.) on seedling density, grain yield and grain Zn concentration in 31 field locations over two years in six countries. Experimental treatments were: (1) low‐Zn seeds and no soil Zn fertilization (control treatment), (2) low‐Zn seeds + soil Zn fertilization, and (3) Zn‐biofortified seeds and no soil Zn fertilization. The wheat experiments were established in China, India, Pakistan, and Zambia, the rice experiments in China, India and Thailand, and the common bean experiment in Brazil. When compared to the control treatment, soil Zn fertilization increased wheat grain yield in all six locations in India, two locations in Pakistan and one location in China. Zinc‐biofortified seeds also increased wheat grain yield in all four locations in Pakistan and four locations in India compared to the control treatment. Across all countries over 2 years, Zn‐biofortified wheat seeds increased plant population by 26.8% and grain yield by 5.37%. In rice, soil Zn fertilization increased paddy yield in all four locations in India and one location in Thailand. Across all countries, paddy yield increase was 8.2% by soil Zn fertilization and 5.3% by Zn‐biofortified seeds when compared to the control treatment. In common bean, soil Zn application as well as Zn‐biofortified seed increased grain yield in one location in Brazil. Effects of soil Zn fertilization and high‐Zn seed on grain Zn density were generally low. This study, at 31 field locations in six countries over two years, revealed that the seeds biofortfied with Zn enhanced crop productivity at many locations with different soil and environmental conditions. As high‐Zn grains are a by‐product of Zn biofortification, use of Zn‐enriched grains as seed in the next cropping season can contribute to enhance crop productivity in a cost‐effective manner.     

Effect of varied soil nitrogen supply on growth and nutrient uptake of young Norway spruce plants grown in a shaded environment

To understand the effect of increased soil N supply on tree growth and nutrient uptake, three-year-old Norway spruce seedlings were grown in pots on low-nutrient mineral forest soil supplemented with N in mineral or organic form. Outdoor shaded growth conditions were used, to test the hypothesis that shaded plants are particularly susceptible to high soil N supply. Plants were harvested eleven months after planting. Shoot growth was not affected by the N supply, but N concentrations in needles and roots were increased in plants supplied with mineral N (150 or 300 mg N [kg soil]^—1). Root growth was drastically reduced and root/shoot ratios were decreased in plants with higher N uptake. A high supply of mineral N to soil also decreased the concentrations of other essential elements (P, K) in the needles and thus had effects on plant growth which may impair the stress resistance of trees. Organic N in the form of keratin (150 mg N [kg soil]^—1) did not influence plant growth significantly. The adverse effects of high mineral N supply were particularly pronounced under shaded conditions in comparison to results from other experiments using higher light intensity and temperature conditions.     

Responses of cucumber grown in recirculating nutrient solution to gradual Mn and Zn accumulation in the root zone owing to excessive supply via the irrigation water

A standard and a high manganese (Mn) level (10 and 160 μM) were combined with a standard and a high zinc (Zn) level (4 and 64 μM) in the nutrient solution supplied to cucumber in closed‐cycle hydroponic units to compensate for nutrient uptake. The concentrations of all nutrients except Mn and Zn were identical in all treatments. The objectives of the experiment were to establish critical Zn and Mn levels in both nutrient solutions and leaves of cucumber grown hydroponically, to assess the impact of gradual Zn and/or Mn accumulation in the external solution on nutrient uptake and gas exchange, and to find whether Mn and Zn have additive effects when the levels of both ions are excessively high in the root zone. The first symptoms of Mn and Zn toxicity appeared when the concentrations of Mn and Zn in the leaves of cucumber reached 900 and 450 mg kg^–1 in the dry weight, respectively. Excessively high Mn or/and Zn concentrations in the leaves reduced the fruit biomass production due to decreases in the number of fruits per plant, as well as the net assimilation rate, stomatal conductance, and transpiration rate, but increased the intercellular CO₂ levels. Initially, the Mn or Zn concentrations in the recirculating nutrient solution increased rapidly but gradually stabilized to maximal levels, while the corresponding concentrations in the leaves constantly increased until the end of the experiment. The uptake of Mg, Ca, Fe, and Cu was negatively affected, while that of K and P remained unaffected by the external Mn and Zn levels. The combination of high Mn and Zn seems to have no additive effects on the parameters investigated.     

Effects of adding wood vinegar to nutrient solution on the growth,photosynthesis, and absorption of mineral elements of hydroponic lettuce

This study was conducted to determine whether using wood vinegar instead of nitric acid to adjust the pH of nutrient solution in hydroponics had any effects on the lettuce. Photosynthesis, mineral elements, water absorption, and the growth of the lettuce were all comparable to those of lettuce in the control group, in which nitric acid was used to adjust the pH. Nitric acid was added to half a unit of Enshi formula to adjust the pH of the control group. The rates of growth, water and mineral element absorption, and photosynthesis were low in lettuce plants grown in nutrient solution with 1 ml L^?1 wood vinegar. However, the lettuce grown in solutions with 0.25 ml L^?1 wood vinegar showed no significant differences from the control group. Therefore, wood vinegar concentration of 0.25 ml L^?1 was found to be sufficient to keep the pH of the nutrient solution within the optimum range for growth.     

Preparation of nitrogen and phosphorus-enriched paddy straw compost and its effect on yield and nutrient uptake by wheat (Triticum aestivum L.)

Summary A nutrient-rich compost from paddy straw was prepared using urea and Mussoorie rock phosphate for N and P enrichment respectively. Inorganic N was partly conserved in the compost by the addition of pyrite. Citric-acid-soluble P also increased with the addition of pyrite. Compost containing about 1.6% total N and 3.3% total P was found to be a good source of P for a wheat crop and also supplied a significant amount of N to the plants.     

The effect of phosphate deficiency on the kinetics of phosphate absorption by sterile excised barley roots,and some factors affecting the ion uptake efficiency of roots

Abstract

The influence of phosphate nutrition on the kinetics of phosphate absorption by sterile excised barley roots was examined. The roots of seedlings grown in dilute CaSO₄ showed uptake kinetics similar to roots grown in phosphate deficient nutrient culture. The absence of microorganisms did not abolish the dual form of the absorption isotherm at pH 4.0

The most important effect of phosphate deficiency for uptake at low phosphate concentration was a marked decrease in the apparent dissociation constant of the ion‐carrier complex postulated to be involved in the uptake process. The results are discussed in relation to kinetic factors which may influence the efficiency of ion uptake by roots of different species of plants, including the apparent dissociation constant, the rate constant for uptake and the concentration of the ion‐carrier system.     

栽培模式、施氮量和播种密度对小麦子粒中锌、铁、锰、铜含量和携出量的影响

用田间试验方法研究了栽培模式、播种密度和施氮量与小麦(Triticum aestivum L.)子粒中锌、铁、锰、铜含量与携出量的关系.结果表明,施用氮肥显著地提高了子粒产量,5种栽培模式中覆膜栽培表现出较大的增产效应,而增大播种密度在本试验条件下的增产作用较小;在30种处理组合下,4种微量元素在小麦子粒中含量的分布趋势均为铁＞锰＞锌＞铜,表明这些元素的含量分布主要受作物自身遗传性状的控制,而人为的栽培措施的影响是有限的,不同处理组合对子粒中铁、锰和铜的含量均有显著性影响,而对锌含量未表现出明显影响;补灌栽培与覆膜栽培相比,前者能显著提高子粒铜含量,施用N肥条件下,子粒锌、铜含量均显著高于不施N肥;覆膜栽培下铁、锰携出量高于其它4种栽培模式,施用N肥显著提高了小麦子粒中锌、铁、锰、铜携出量.此外,不同栽培模式、播种密度和施氮量下土壤中有效态锌含量的变异幅度极小.