Organic phosphorus utilization by wheat plants under sterile conditions

An experiment was set up to make a critical assessment of the role of organic P (Po) in soil solution in the nutrition of wheat plants under sterile conditions. Three concentration gradients of Po (17.08, 27.31 and 37.61 M l^-1) were created in a sterilized Oxisol by fertilization with a soil solution prepared by a dry freezing technique and containing antibiotics to minimize microbial growth. Due to the high P fixing capacity of the Oxisol and high buffering capacity of inorganic P (Pi), as compared to Po, a negligible change in Pi concentration occurred, due to fertilization after equilibrium in soil solution. Phosphorus supply had a positive effect on dry matter and P concentration of the plants. Acid phosphatase secretion by plant roots was 5–11 times higher in Po treatments than in the respective Pi treatments. No alkaline phosphatase activity was detected, confirming the absence of microbial activity in our system. Net P inflow into plants was significantly higher in the Pi + Po treatments at all three Po concentrations than in the respective Pi (control) treatment, providing evidence for the role of Po in the P nutrition of plants. It was hypothesized that plants secrete phosphatases in response to the presence of Po in soil solution and Po might be responsible for the increase in P influx to wheat plants.     

Effect from horizontally dividing the root system of wheat plants having different phosphorus efficiencies

The mechanisms of phosphate (P) mobilized by wheat were studied with the typically efficient or inefficient genotypes grown in a split‐pot experiment. The split‐pot was composed of two parts, the lower part was a 2‐L plastic pot containing two liters of nutrient solution and the upper part was a PCV tube six cm in diameter by eight cm high and with a nylon net bottom. The tube which was fixed on the pot lid held 250 g quartz sand. In the lid was drilled a small hole in order to add culture solution and 3% hydrogen perioxide (H₂O₂) instead of aerating. Two seedlings were planted in the quartz sand of each of the tubes. Ponnamperuma's recipe was used for preparing the culture solution. For each of the three genotypes tested, four P treatments were: (i) with 0.5 g TCP as the only P source added to the solution, (ii) with 0.5 g TCP as the only P source added in quartz sand, (iii) without any P, and (iv) the check (CK). Sodium dihydrogen phosphate (NaH₂PO₄) was the P source in culture solution. When tricalcium phosphorus (TCP) was added to the solution, the amount of calcium (Ca) taken up by the efficient genotype, Lovrin 10, was 2.7 and 3.6 times higher than those of the inefficient ones, Chinese Spring and 80–55. Also, the amount of P mobilized and released by Lovrin 10 was 30% and 77% higher than those of the other two genotypes. When TCP was added in the quartz sand, the genotypical differences in Ca influx or P mobilization had the same tendency as above. Chinese Spring and 80–55 could not complete their life cycle. However, Lovrin 10 not only flowered but bore fruit as well, indicating absorption of more Ca and active mobilization of P were the basic characters of the efficient genotype, Lovrin 10.     

应用数字图像进行小麦氮素营养诊断中图像分析方法的研究

简便、快速、经济地诊断作物氮素营养状况是实施氮肥用量调控的关键。利用数码相机对作物冠层进行拍照, 通过图像处理软件获得作物色彩参数, 根据色彩参数与作物氮素营养状况的关系可以对其氮素丰缺进行诊断。针对作物数字图像色彩参数的获取方法, 结合小麦多水平氮肥试验, 采用遥感软件PCI Geomatics的非监督分类功能, 将小麦图像分为土壤、反光叶面和不反光叶面, 与Adobe Photoshop 软件普通图像处理方法对照, 比较分析了小麦图像不同类别叶片的8 种色彩参数与SPAD 值及植株全氮的相关性。结果表明, 返青期小麦反光叶面的G/R 与R/(R+G+B)色彩参数能较好地反映小麦的氮素营养状况; 拔节期不反光叶面和反光叶面的R/(R+G+B)色彩参数与植株全氮相关性较好。利用普通图像处理软件获得色彩参数的方法有待改进, 图像分类后能够提高其色彩参数对作物氮素营养诊断的准确性。     

Assessing the potential use of two portable chlorophyll meters in diagnosing the nutritional status of plants

The SPAD-502 and the FieldScout CM 1000 chlorophyll meters were compared in their performance in diagnosing the nutritional status of plants. Leaves of a wide range of greenness were used to push the sensitivity of the tools to their limits. Both devices showed high reproducibility when used by different operators. The SPAD-readings were well-correlated with leaf nitrogen (N) concentrations, since leaves from heavily fertilized plants were not included in the sample population. The FieldScout-readings showed a marked saturation curve with the leaf N concentration, thus it cannot be used as a reliable N nutritional status index. The results also showed that the use of SPAD-502 in the diagnosis of the nutritional status of an orchard requires the establishment of specific critical concentrations for cultivars and sampling dates. The SPAD-502 appeared to have potential in the diagnosis of the nutritional status of the orchard for nutrients other than N.     

Effect of fresh bark media on phosphorus status of tomato plants1

Abstract

Phosphorus status of tomato (cv Floradel) was determined in two experiments where plants were grown in fresh or aged softwood bark or a control medium (perlitetsand, 3:1). The P concentration of plants grown in fresh bark was lower than for those grown in other media. Highly significant correlation coefficients were obtained between growth and P concentrations. The results strongly suggest that growth depression of plants grown in fresh bark is due to bark‐induced P deficiency.     

不同磷水平下玉米和小麦植株亚细胞中镉的积累

Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0,0.12,0.60 and 3.0mmol L^-1) and two levels of cadmium(0 and 4.0umol L^-1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall,cytoplasm and vacuoles of roots and leaves were examined by cell fractionation techniques.With increasing phosphorus in medium,the contents of P in cell wall,cytoplasm and vacuoles of corn and wheat roots and leaves increased.The highest content of P was observed in cell wall,next in vacuoles,and the lowest in cytoplasm.The wheat subcellular fractions in both roots and leaves hab higher concentrations of phosphorus than those of corn.Increasing phosphorus in medium significantly inhibited the intracellular Cd accumulation in both species,However,at P concentration up to 3.0mmol L^-1,the Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellular Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellualr Cd content in corn and wheat leaves.Compared with corn,the wheat roots had a higher Cd content in the cell wall and vacuoles and a lower in cytoplasm,while in leaf subcellular fractions the wheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm,The results indicate that phosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vaculoes by forming insoluble Cd phosphate.     

Detection of nitrogen and phosphorus nutrient status in winter wheat using spectral radiance

Nitrogen (N) and phosphorus (P) are major limiting nutrient elements for crop production and continued interest lies in improving their use efficiency. Spectral radiance measurements were evaluated to identify optimum wavelengths for dual detection of N and P status in winter wheat (Triticum aestivum L.). A factorial treatment arrangement of N and P (0, 56, 112, and 168 kg N ha^‐1 and 0, 14.5, and 29 kg P ha^‐1) was used to further study N and P uptake and associated spectral properties at Perkins and Tipton, Oklahoma. A wide range of spectral radiance measurements (345–1, 145 nm) were obtained from each plot using a PSD 1000 Ocean Optics fiber optic spectrometer. At each reading date, 78 bands and 44 combination indices were generated to test for correlation with forage biomass and N and P uptake. Additional spectral radiance readings were collected using an integrated sensor which has photodiode detectors and interference filters for red and NIR. For this study, simple numerator/denominator indices were useful in predicting biomass, and N uptake and P uptake. Numerator wavelengths that ranged between 705 and 735 nm and denominator wavelengths between 505 and 545 nm provided reliable prediction of forage biomass, and N and P uptake over locations and Feekes growth stages 4 through 6. Using the photodiode sensor, NDVI [(NIR‐red)/(NIR+red)] and NR [(NIR/red)], were also good indices to predict biomass, and N and P uptake. However, no index was found to be good for detecting solely N and P concentration either using the spectrometer or photodiode sensor.     

Specific activity of phosphorus in mycorrhizal and non-mycorrhizal plants in relation to the availability of phosphorus to plants

Phosphate was allowed to react with a soil to which iron hydroxide had been added. The P was then labelled by a subsequent addition of ³²P. Soil P was extracted by 10 mm CaCl₂, 0.5 m NaHCO₃, and acid NH₄F solutions and the specific activity of P in the extracts was measured. Subterranean clover plants were grown both with and without a mycorrhizal fungus. Phosphorus contents and the specific activities of P in the plant shoots were determined.For mycorrhizal plants, adding iron hydroxide had no effect on the amount of P taken up, but for non-mycorrhizal plants it decreased the uptake. However there was no effect of iron hydroxide or of mycorrhizal infection on the specific activity of P in the plants. Adding iron hydroxide had no effect on the amount of P extracted by acid NH₄F, but decreased the P extracted by 10mm CaCl₂ and by 0.5 m NaHCO₃. The specific activity of P in the extracts was not affected by the addition of iron hydroxide and was the same for the three extractants. Further, the specific activity of P in all extractants was similar to that of P in both mycorrhizal and non-mycorrhizal plants. Thus differences in the availability of soil P to mycorrhizal and non-mycorrhizal plants and to the extractants were not reflected by differences in labelling. It therefore follows that lack of difference in specific activity between mycorrhizal and non-mycorrhizal plants does not eliminate the possibility that mycorrhizal plants can obtain P that was unavailable to non-mycorrhizal plants.     

Soil available phosphorus status determines indigenous mycorrhizal colonization of field and glasshouse-grown spring wheat from Argentina

Wheat production (Triticum aestivum L.) has increased across the world during last century with the intensification of agriculture. Phosphorus (P) fertilization is a common practice to improve wheat growth in Argentina. We investigate whether indigenous arbuscular mycorrhizal colonization (AMC) of hard red spring wheat is controlled by shoot P content (SPc) or by available soil P in an agricultural soil from the southeastern Argentine Pampas. In the field, AMC was monitored four times during two growing seasons of a conventional wheat crop. Treatments were: without P supply, annual supply of 11 and 22 kg P ha⁻¹ during the last 5 years, and 164 kg P ha⁻¹ applied once 5 years before the experiment. In the glasshouse, AMC was assessed three times in wheat growing in pots filled with the soil from unfertilized plots; treatments were: P (0 and 20 mg P pot⁻¹), and nitrogen (N) fertilization (0 and 150 mg N pot⁻¹). A range of soil P between 6 and 60 mg P kg⁻¹ was obtained and the AMC ranged from 1% to 67% of root length colonized under both field and glasshouse conditions. P supplied annually increased growth and SPc but decreased AMC. N fertilization did not affect growth or AMC. Variations in SPc did not account for AMC. Variability in AMC was best accounted for local current soil available P content (r² = 0.59). A linear-plateau relationship between soil P and indigenous AMC was established in wheat plants growing under contrasting environmental and experimental (field and glasshouse) conditions. Indigenous AMC was depressed by available soil P in the range 0–27 mg P kg⁻¹ (a decrease of 2.8% mg P⁻¹ kg⁻¹). Above 27 mg P kg soil⁻¹, AMC was stabilized at about 10%. Grain yield increased with fertilization and the highest relative shoot dry matter in field was obtained at 15.5 mg P kg soil⁻¹. The soil P range that ensures high wheat production without deterring indigenous AMC is discussed.     

A simple model for phosphorus uptake kinetics of wheat seedlings

A simple model to compare and predict phosphorus (P) uptake behavior of plants may be useful to agronomists. A predictive equation based on Michaelis‐Menten kinetics was developed for this purpose. Kinetic parameters for use in the model were determined in an experiment using two cultivars of winter wheat grown for 21 days in 14 soil treatments, including seven P levels, each in fumigated and unfumigated soil. In another experiment, the same wheat cultivars were grown for 7, 14, or 21 days at one soil P level in both fumigated and unfiimigated soil. Using parameter values developed in the first experiment with multiple P levels and one time period, the model closely (R²=0.966, P<0.001) predicted P uptake in the second experiment with one P level over multiple time periods. The model could be a useful agronomic tool because of its simplicity and because no data need be collected from artificial growing conditions.     

不同品种小麦根际磷转化及VA菌根对小麦根际磷转化的影响

采用三室根箱研究了磷高效小麦 81( 85)-5-3-3-3及磷低效NC37两个小麦品种根际磷转化及VA菌根对根际土壤磷转化的影响。结果表明 ,磷胁迫下 ,81( 85)-5-3-3-3的吸磷量略高于NC37,两种小麦品种根际土壤均形成了明显的Olsen-P ,Ca2-P ,Ca8-P ,Al P等形态磷的耗竭区。两种小麦品种在不施磷肥和施用磷肥下接种VA菌根 ,小麦的生物量、植株磷浓度、小麦根际Olsen-P,Ca2-P ,Ca8-P,Al-P ,Fe-P的消耗量均显著增加 ;根际、非根际土壤各形态磷素的浓度梯度明显降低。     

Phosphorus acquisition and wheat growth are influenced by shoot phosphorus status and soil phosphorus distribution in a split‐root system

Root proliferation and greater uptake per unit of root in the nutrient‐rich zones are often considered to be compensatory responses. This study aimed to examine the influence of plant phosphorus (P) status and P distribution in the root zone on root P acquisition and root and shoot growth of wheat (Triticum aestivum L.) in a split‐root soil culture. One compartment (A) was supplied with either 4 or 14 mg P (kg soil)^–1, whereas the adjoining compartment (B) had 4 mg P kg^–1 with a vertical high‐P strip (44 mg kg^–1) at 90–110 mm from the plant. Three weeks after growing in the split‐root system, plants with 4 mg P kg^–1 (low‐P plants) started to show stimulatory root growth in the high‐P strip. Two weeks later, root dry weight and length density in the high‐P strip were significantly greater for the low‐P plants than for the plants with 14 mg P (kg soil)^–1. However, after 8 weeks of growth in the split‐root system, the two P treatments of compartment A had similar root growth in the high‐P strip of compartment B. The study also showed that shoot P concentrations in the low‐P plants were 0.6–0.8 mg g^–1 compared with 1.7–1.9 mg g^–1 in the 14 mg P kg^–1 plants after 3 and 5 weeks of growth, but were similar (1.1–1.4 mg g^–1) between the two plants by week 8. The low‐P plants had lower root P concentration in both compartments than those with 14 mg P kg^–1 throughout the three harvests. The findings may indicate that root proliferation and P acquisition under heterogeneous conditions are influenced by shoot P status (internal) and soil P distribution (external). There were no differences in the total root and shoot dry weight between the two P treatments at weeks 3 and 5 because enhanced root growth and P uptake in the high‐P strip by the low‐P plants were compensated by reduced root growth elsewhere. In contrast, total plant growth and total root and shoot P contents were greater in the 14 mg P kg^–1 soil than in the low‐P soil at week 8. The two P treatments did not affect the ratio of root to shoot dry weight with time. The results suggest that root proliferation and greater P uptake in the P‐enriched zone may meet the demand for P by P‐deficient plants only for a limited period of time.     

土壤压实对土壤物理性质及小麦氮磷钾吸收的影响

为了研究土壤压实对土壤物理性质以及小麦养分吸收情况的影响,在2006和2007年进行了两轮田间试验.试验中,先用旋耕机对田块进行旋耕,耕深10cm,然后使用手扶式、轮式、履带式拖拉机在旋耕后的田块中通过1次(T1)、2次(T2)、4次(T3)以对土壤进行压实处理,对照组(T4)不作任何压实处理.压实处理后再次对土壤表层进行浅旋耕,耕深5 cm,耕后用播种机进行小麦播种,小麦品种为南京-601.试验结果发现,次表层土壤的压实处理显著影响次表层土壤的容重,孔隙度,小麦蛋白质含量以及植物中N、P、K的含量.除次表层的土壤容重在T3组中最大,T4组中最小外,其他参数值在T4组中最大,T3组中最小.并且,随着次表层土壤压实程度的增加,几乎所有的参数(土壤容重除外)都有所减少.不过,与第一年相比,参数值在第二年略有增加.总之,土壤压实严重破坏土壤结构,不利于小麦对养分的吸收.     

Comparative phosphorus requirement of canola and wheat

The yield response of canola (also known as rape, Brassica napus) and wheat (Triticum aestivum) to applications of phosphorus (P) as single superphosphate was measured in three field experiments in south‐western Australia. The P was banded with the seed while sowing at 4 cm depth. The P requirements of the species was determined from the amount of P required to produce 90% of the maximum yield. Canola consistently required less P than wheat, from 50 to 55% less P for dried tops, and 30 to 58% less P for seed. The P concentration and P content (P concentration multiplied by yield) in dried tops or seed was consistently larger for canola than wheat.     

Effectiveness of different precipitated phosphates as phosphorus sources for plants

Abstract. Eleven precipitated phosphates were evaluated as sources of phosphorus (P) for plant growth by comparing their effectiveness with that of monocalcium phosphate, a source of water soluble P that is generally considered to be fully plant available. The precipitated phosphates comprised struvites recovered from waste water discharges (mainly magnesium ammonium phosphate), laboratory synthesised struvites, a synthetic iron phosphate and a recovered calcium phosphate. Precipitating phosphates in these forms could be a way for removing P from waste water before it is discharged to rivers, so reducing the risk of eutrophication. Application to agricultural land would be one potential use for such phosphates. Evaluation was by pot experiments with a sandy loam soil and with a sandy clay loam soil using perennial ryegrass ( Lolium perenne) as the test crop. The soils differed in pH (6.6 and 7.1) and in Olsen P (28 and 11 mg L⁻¹). Measured variables were grass dry matter (DM) yield and grass P concentration which were used to calculate offtake of P in the harvested grass. DM yields of ryegrass and P offtakes given by the synthetic and recovered struvites were not significantly different statistically either between themselves or to MCP applied at the same rate. On this basis these struvites could be used to recycle P to similar soils and the effect of the P on crop yield should be similar to that of MCP     

Soil and plants nutrient status and wheat growth after mycorrhiza inoculation with and without vermicompost

Two vermicompost treatments providing 45 (V1) and 90 (V2) kg P ha^?1 and mycorrhizae (M) inoculation were evaluated alone and in combinations for wheat (Triticum aestivum L.) growth and soil fertility status. The treatments included; the Control, nitrogen (N): dipotassium oxide (K₂O) as basal dose (BD; 120:60 kg ha^?1), N: phosphorus pentoxide (P₂O₅): K₂O as recommended dose (RD; 120:90:60 kg ha^?1), BD+Myccorhiza (BDM), BD+V1 (BDV1), BDM+V1 (BDMV1), BD+V2 (BDV2), and BDM+V2 (BDMV2). Combination of mycorrhizae and vermicompost (BDMV1 and BDMV2) significantly and maximally improved the growth, plant N, phosphorus (P), and micronutrient concentrations over the control, reduced the soil pH by 5 and 6%, increased OM by 25 and 112%, total N by 41%, and extractable P up to 200% while the extent of improvement was directly related to the content of added vermicompost. Results indicated that vermicompost at either level synergistically affected the mycorrhizae in plant nutrition as well as improved soil fertility status and soil chemical properties.     

Remobilization and utilization of phosphorus in wheat cultivars under induced phosphorus deficiency

A solution culture study was conducted to compare the phosphorus (P) remobilization efficiency of four wheat cultivars under induced P deficiency. Wheat cultivars, i.e. Sarsabz, NIA-Sunder, NIA-Amber and NIA-Saarang were initially grown on adequate P nutrition for 30 days and then exposed to P-free nutrient solution for next 15 days to study P remobilization. Completely randomized design (CRD) with ten replicates per cultivar was employed. Cultivars varied for biomass production, P concentration, P uptake, and P utilization efficiency at both harvests. Overall, more than 75% of absorbed P was mobilized from older leaves to younger leaves as well as roots of all cultivars during P-omission period. However, cultivars could not produce significant variations (P < 0.05) in P remobilization, which implied that P remobilization was only a stress response to P deficiency in wheat cultivars and it could not be related to P utilization efficiency of these cultivars.     

溶磷菌剂对施磷复垦土壤无机磷形态及油菜磷吸收的影响

  目的  通过分析攀西高原不同轮作模式对土壤肥力和phoD基因群落结构的影响,以期深入认识该生境下土壤磷素循环机制,建立合理的轮作制度。  方法  以攀西高原五种不同轮作制度下的休闲期土壤为研究材料,通过化学分析和高通量测序技术对土壤理化性质以及土壤中phoD基因群落结构与多样性进行研究。  结果  不同轮作制度处理下,相较于撂荒处理,土壤有效磷含量显著提高,全氮、碱解氮、有机碳含量显著降低（P < 0.05）。土壤中酸性磷酸酶活性（Acid phosphatase, ACP）显著高于碱性磷酸酶（Alkaline phosphatase, ALP）和中性磷酸酶（Neutral phosphatase, NP）,且在大麦－烤烟轮作制度中最高（13358 U g⁻¹）。就phoD基因的shannon多样性指数而言,在大麦－烤烟轮作制度下最高,而在苦荞－烤烟轮作下最低。不同轮作制度下phoD群落结构差异明显,变形菌门（Proteobacteria）、放线菌门（Actinobacteria）是不同轮作模式的主要门类,慢生根瘤菌(Bradyrhizobium)为主要优势属。冗余分析显示,有机碳、pH是该生境下驱动phoD基因群落结构变化的重要理化因子。  结论  与撂荒相比,轮作明显改变了土壤肥力和磷酸酶活性,形成了不同的土壤phoD基因群落结构。五种轮作制度中以苦荞－烤烟轮作对phoD基因多样性指数影响最为显著,大麦－烤烟轮作对土壤养分含量和碱性磷酸酶活性影响最大。     

磷素子粒生产效率不同品种的小麦磷素吸收利用差异

盆栽试验研究了130份小麦不同生育时期的干物重、磷素含量、子粒产量等指标,采用组内最小平方和的动态聚类方法将供试品种按磷素子粒生产效率从低到高依次分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ 6个类型,研究不同类型磷素吸收利用的差异。结果表明: 1）供试品种的磷素子粒生产效率差异较大（CV=1660%）,Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ类品种的平均磷素子粒生产效率为P 13629、15167、16916、18589、20132、24466 g/g。子粒产量随磷素子粒生产效率提高呈增加趋势（r=03203**）。2）不同生育时期,小麦植株磷浓度与吸磷量类型间差异显著或极显著。成熟期磷素子粒生产效率与植株磷浓度极显著正相关（r=06969**）,子粒产量与抽穗期、成熟期植株吸磷量显著或极显著相关（r=02966*、r=09271**）。3）不同生育时期磷素干物质生产效率的类间差异均达显著水平; 成熟期磷素干物质生产效率与磷素子粒生产效率极显著正相关 （r=07391**）。4）拔节期、抽穗期和成熟期干物重均表现出随磷素子粒生产效率增加而增加的趋势,成熟期尤为突出。拔节期成熟期磷素吸收量是影响子粒产量形成的重要因素,磷素子粒生产效率高的品种在拔节期后有较强干物质和子粒产量形成能力。