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1.
Wheat leaf properties affecting the absorption and subsequent translocation of foliar-applied phosphoric acid fertiliser 总被引:1,自引:0,他引:1
Background and aims
Although foliar fertilisation using liquid forms of phosphorus (P) is not a new concept, its adoption has been hindered by a limited understanding of the variability in performance of fluid forms of foliar P applied to broadacre crops. There is a need to identify how the surface structure of leaves influences the absorption and subsequent translocation of foliar-applied P in above ground plant parts.Methods
This study examined the surface properties of wheat leaves using scanning electron microscopy and measured the recovery of foliar-applied fertiliser that was labelled with either 32P or 33P from both the adaxial (upper) and abaxial (lower) leaf sides into untreated plant parts.Results
We found that the adaxial leaf surface absorbed and translocated more foliar-applied P away from the treated leaf than the abaxial surface, likely related to the higher abundance of trichomes and stomata present on that side of the leaf. The recovery of the foliar-applied fertiliser varied with rate and timing of application; ranging from <30 % to as much as 80 % of the adaxial-applied fertiliser translocated from the treated leaf into the wheat ear.Conclusions
This study demonstrated that the differences in surface morphological features between leaf sides influenced the combined absorption and subsequent translocation of foliar-applied P in the above ground plant parts. This is due to a direct effect on the foliar pathway and/or due to differences in wettability affecting both the leaf coverage and drying time of fertilisers on the leaves. Although foliar fertilisation in this study contributed less than 10 % of the total P in the plant, it provided a more efficient pathway for P fertilisation than soil-applied P. 相似文献2.
Muhammad Nadeem Alain Mollier Christian Morel Muhammad Shahid Muhammad Aslam Muhammad Zia-ur-Rehman Muhammad Ashfaq Wahid Sylvain Pellerin 《Plant and Soil》2013,367(1-2):327-338
Background and Aims
This study aimed to evaluate the responses of anti-oxidative enzymes and stress-related hormones in E. agallocha to different levels of Pb stresses at different exposure time.Methods
The study was carried out in greenhouse, and the pot trials were conducted to investigate the stress responses of root and leaf to Pb exposure in seedlings of E. agallocha.Results
Pb stress posed higher toxic effects on root than leaf at day 49. At days 1, 7and 49, the activities of superoxide dismutase and peroxidases increased significantly, especially in leaves. Significant increases of malondialdehyde content were also observed at day 1 but significant increases of proline were only found at day 49 in leaf. Increases of salicylic acid and jasmonic acid were mainly observed in the leaves at day 1.Conclusions
E. agallocha was sensitive to Pb stress and damages, but tended to acclimate to low levels of Pb stresses by increasing and maintaining high levels of SOD and POD activities even at the later stage of exposure (day 49). Increases of endogenous SA and JA concentrations at day 1 might also involve in the plant’s tolerance to Pb stress. 相似文献3.
J. B. Goloran C. R. Chen I. R. Phillips Z. H. Xu L. M. Condron 《Plant and Soil》2014,374(1-2):565-578
Background and aims
Soil phosphorus (P) indices that have been originally developed and applied to agricultural soils for predicting P uptake by plants were examined in a pot experiment to determine the most suitable index for P availability in bauxite-processing residue sand (BRS).Methods
Pot trials with ryegrass were established using BRS that had been amended with various organic (greenwaste compost, biochar and biosolids) and inorganic (zeolite) materials and different levels of di-ammonium phosphate fertiliser. Soil P availability indices tested included anion-exchange membrane (AEM-P), 0.01 M calcium chloride (CaCl2-P), Colwell-P, and Mehlich 3-P.Results
AEM-P was found to most closely reflect the available P status in BRS across all treatments, and had the strongest associations with plant P uptake compared to Colwell-P, Mehlich 3-P and CaCl2-P. AEM-P was more closely correlated with P uptake by ryegrass than other P indices, while Colwell-P was closely related to leaf dry matter. Interestingly, a strong inverse relationship between plant indices and pH in BRS growth media was observed, and an adequate level of plant P uptake was found only in 15 year-old rehabilitated BRS with pH <?8.0.Conclusions
AEM-P was found to be the most suitable index for evaluating P availability in highly alkaline BRS and pH was an important parameter affecting uptake of P by ryegrass. Importantly, time is required (> 5 years) before improved uptake of P by plants can be observed in rehabilitated residue sand embankments. 相似文献4.
Boron distribution and mobility in navel orange grafted on citrange and trifoliate orange 总被引:2,自引:0,他引:2
Gui-Dong Liu Rui-Dong Wang Li-Shu Wu Shu-Ang Peng Yun-Hua Wang Cun-Cang Jiang 《Plant and Soil》2012,360(1-2):123-133
Background and Aims
In China, boron (B) deficiency is frequently observed in citrus orchards, and is responsible for considerable loss of productivity and quality. A better understanding of B distribution and remobilization within orange plants is important for developing programs in rational fertilization and effective mitigation of B-deficiency. In the present study (i) the distribution of newly absorbed B and (ii) the translocation of foliar-applied B in ‘Newhall’ navel orange grafted on citrange and trifoliate orange was investigated.Methods
10B was applied in the nutrient solution or sprayed on the lower-old leaves of both grafted plants for 35?days.Results
In the 10B uptake experiment, citrange-grafted plants showed higher newly acquired total B content and B concentration in both lower-old and upper-old leaves than those in trifoliate-orange-grafted plants. The newly absorbed B in the new leaves was much higher than that in the lower-old leaves and the upper-old leaves in both grafted plants. Foliar application of 10B to the lower-old leaves resulted in B translocation to the upper-old leaves and the new leaves with preference mainly to the new leaves in both citrange and trifoliate orange when root B supply was relatively low. However, 10B sprayed to the lower-old leaves not only did not increase the abundance percentage of 10B in the root, but also reduced B concentration and the total B content in the root.Conclusions
The results suggest that foliar-applied B can be translocated within both grafted plants, which might also depress B uptake from root medium with low B supply. Rootstock can affect the B distribution in old leaves in navel orange, and newly absorbed B was preferentially transported to the new leaves. 相似文献5.
Uptake of zinc and phosphorus by plants is affected by zinc fertiliser material and arbuscular mycorrhizas 总被引:2,自引:0,他引:2
Stephanie J. Watts-Williams Terence W. Turney Antonio F. Patti Timothy R. Cavagnaro 《Plant and Soil》2014,376(1-2):165-175
Background and Aims
Water solubility of zinc (Zn) fertilisers affects their plant availability. Further, simultaneous application of Zn and phosphorus (P) fertiliser can have antagonistic effects on plant Zn uptake. Arbuscular mycorrhizas (AM) can improve plant Zn and P uptake. We conducted a glasshouse experiment to test the effect of different Zn fertiliser materials, in conjunction with P fertiliser application, and colonisation by AM, on plant nutrition and biomass.Methods
We grew a mycorrhiza-defective tomato genotype (rmc) and its mycorrhizal wild-type progenitor (76R) in soil with six different Zn fertilisers ranging in water solubility (Zn sulphate, Zn oxide, Zn oxide (nano), Zn phosphate, Zn carbonate, Zn phosphate carbonate), and supplemental P. We measured plant biomass, Zn and P contents, mycorrhizal colonisation and water use efficiency.Results
Whereas water solubility of the Zn fertilisers was not correlated with plant biomass or Zn uptake, plant Zn and P contents differed among Zn fertiliser treatments. Plant Zn and P uptake was enhanced when supplied as Zn phosphate carbonate. Mycorrhizal plants took up more P than non-mycorrhizal plants; the reverse was true for Zn.Conclusions
Zinc fertiliser composition and AM have a profound effect on plant Zn and P uptake. 相似文献6.
Aliaksandr Kolbas Lilian Marchand Rolf Herzig Erika Nehnevajova Michel Mench 《Plant and Soil》2014,376(1-2):377-397
Background and aims
The potential use of a metal-tolerant sunflower mutant line for both biomonitoring and phytoremediating a Cu-contaminated soil series was investigated.Methods
The soil series (21–1,170 mg Cu kg?1) was sampled in field plots at control and wood preservation sites. Sunflowers were cultivated 1 month in potted soils under controlled conditions.Results
pH and dissolved organic matter influenced Cu concentration in the soil pore water. Leaf chlorophyll content and root growth decreased as Cu exposure rose. Their EC10 values corresponded to 104 and 118 μg Cu L?1 in the soil pore water, 138 and 155 mg Cu kg?1 for total soil Cu, and 16–18 mg Cu kg?1 DW shoot. Biomass of plant organs as well as leaf area, length and asymmetry were well correlated with Cu exposure, contrary to the maximum stem height and leaf water content.Conclusions
Physiological parameters were more sensitive to soil Cu exposure than the morphological ones. Bioconcentration and translocation factors and distribution of mineral masses for Cu highlighted this mutant as a secondary Cu accumulator. Free Cu2+ concentration in soil pore water best predicted Cu phytoavailability. The usefulness of this sunflower mutant line for biomonitoring and Cu phytoextraction was discussed. 相似文献7.
Shaul Naschitz Amos Naor Shmuel Wolf Eliezer E. Goldschmidt 《Trees - Structure and Function》2014,28(3):879-890
Key message
Autumnal senescence of apple in a warm climate corresponds to accumulated degree-days beneath 22 °C. Summer drought delays senescence and enables replenishment of carbohydrate reserves. Recovery of the root system plays a key role.Abstract
Autumnal senescence of apple (Malus domestica Borkh.), a deciduous, temperate climate species, is triggered by a rather abrupt temperature drop, down to the lower teens. Under the warmer, east Mediterranean climate of northern Israel, the temperature drop is gradual and much more moderate. Another characteristic of this climate is the complete lack of precipitation during summer. The aim of the present study was to elucidate the effects of summer drought on seasonal leaf senescence in a warm autumn. We hypothesized that summer drought delays senescence due to an increased demand for carbohydrates during autumn. The advent of autumnal senescence was followed for 3 years (2009–2011) on trees exposed to various levels of drought. Total canopy green area (effective leaf area, ELA) and hue angle were estimated periodically by means of image analysis, as a measure of leaf drop and autumnal color change. Photosynthesis, midday stem water potential, and roots’ non-structural carbohydrate contents were measured on several occasions. The time course of leaf drop followed the decline in air and soil temperatures. The rate of decline in ELA closely corresponded to accumulated degree-days beneath 22 °C in the soil, a much higher temperature threshold than previously reported for apple. Drought stress during the summer delayed leaf senescence even further, when compared with well-irrigated trees. Leaves maintained their photosynthetic functionality throughout autumn, until late December. The delayed senescence enabled replenishment of root carbohydrate reserves, which is critical for next year’s growth and fruiting. The eco-physiological significance of the findings is discussed. 相似文献8.
Fabián G. Scholz Sandra J. Bucci Guillermo Goldstein 《Trees - Structure and Function》2014,28(5):1475-1487
Key message
Total leaf hydraulic dysfunction during severe drought could lead to die-back in N. dombeyi , while hydraulic traits of A. chilensis allow it to operate far from the threshold of total hydraulic failure.Abstract
Die-back was observed in South America temperate forests during one of the most severe droughts of the 20th century (1998–1999). During this drought Austrocedrus chilensis trees survived, whereas trees of the co-occurring species (Nothofagus dombeyi) experienced symptoms of water stress, such as leaf wilting and abscission, before tree die-back occurred. We compared hydraulic traits of these two species (a conifer and an angiosperm species, respectively) in a forest stand located close to the region with records of N. dombeyi mass mortality. We asked whether different hydraulic traits exhibited by the two species could help explain their contrasting survivorship rates. Austrocedrus chilensis had wide leaf safety margins, which appear to be the consequence of relatively high leaf-and-stem capacitance, large stored water use, strong stomatal control and ability to recover from embolism-induced loss of leaf hydraulic capacity. On the other hand, N. dombeyi even though had a stem hydraulic threshold of ?6.7 MPa before reaching substantial hydraulic failure (P88), leaf P88 occurred at leaf water potentials of only ?2 MPa, which probably are reached during anomalous droughts. Massive mortality in N. dombeyi appears to be the result of the total loss of leaf hydraulic conductance leading to leaf dehydration and leaf drop. Drought occurs during the summer and it is highly likely that N. dombeyi cannot recover its photosynthetic surface to produce carbohydrates required to avoid tissue injury in the winter season with subfreezing temperatures. Strong hydraulic segmentation in N. dombeyi does not seem to have an adaptive value to survive severe droughts. 相似文献9.
Bárbara Elias Reis Hodecker Nairam Félix De Barros Ivo Ribeiro Da Silva Valdir Diola Jorge Eduardo Souza Sarkis Marcelo Ehlers Loureiro 《Plant and Soil》2014,384(1-2):185-199
Background
Water and nutritional restrictions are limiting factors for the growth of Eucalyptus trees in tropical climates. In the dry season, boron (B) uptake is severely affected.Aims
The objectives of this study were to evaluate the phloem mobility of B and whether its deficiency can increase plant sensitivity to osmotic stress. It was also tested to what extent foliar application of B could mitigate the negative effects of drought under low B supply.Methods
Seedlings of a drought tolerant Eucalyptus urophylla (Blake, S. T.) clone were grown in nutrient solution, subjected to low availability of B for 25 days, and then submitted to a progressive osmotic stress. After imposition of osmotic stress, B was applied to young or mature leaves.Results
B applications, mainly to mature leaf, stimulated root growth and delayed dehydration under osmotic stress and led to an increased B translocation and carbon isotopic composition. The expression of B transporters and pectin metabolism genes were also increased in water-stressed plants supplied with B by foliar application.Conclusions
B deficiency led to increased plant dehydration and decreased root growth under osmotic stress. The application of B to mature leaf of water-stressed plants proved effective in mitigating the negative effects of water deficit in root growth. 相似文献10.
Managing agricultural phosphorus for water quality protection: principles for progress 总被引:1,自引:0,他引:1
Peter J. A. Kleinman Andrew N. Sharpley Richard W. McDowell Don N. Flaten Anthony R. Buda Liang Tao Lars Bergstrom Qing Zhu 《Plant and Soil》2011,349(1-2):169-182
Background
The eutrophication of aquatic systems due to diffuse pollution of agricultural phosphorus (P) is a local, even regional, water quality problem that can be found world-wide.Scope
Sustainable management of P requires prudent tempering of agronomic practices, recognizing that additional steps are often required to reduce the downstream impacts of most production systems.Conclusions
Strategies to mitigate diffuse losses of P must consider chronic (edaphic) and acute, temporary (fertilizer, manure, vegetation) sources. Even then, hydrology can readily convert modest sources into significant loads, including via subsurface pathways. Systemic drivers, particularly P surpluses that result in long-term over-application of P to soils, are the most recalcitrant causes of diffuse P loss. Even in systems where P application is in balance with withdrawal, diffuse pollution can be exacerbated by management systems that promote accumulation of P within the effective layer of effective interaction between soils and runoff water. Indeed, conventional conservation practices aimed at controlling soil erosion must be evaluated in light of their ability to exacerbate dissolved P pollution. Understanding the opportunities and limitations of P management strategies is essential to ensure that water quality expectations are realistic and that our beneficial management practices are both efficient and effective. 相似文献11.
Sarah R. Noack Mike J. McLaughlin Ronald J. Smernik Therese M. McBeath Roger D. Armstrong 《Plant and Soil》2014,378(1-2):125-137
Background and aims
As plants approach maturity and start to senesce, the primary sink for phosphorus (P) is the seed but it is unclear how plant P status affects the resulting P concentration and speciation in the seed and remaining plant parts of the residues. This study was established to measure how P speciation in different parts of wheat and canola is affected by plant P status.Methods
Wheat and canola grown in the glasshouse were supplied three different P rates (5, 30 and 60 kg P ha?1 equivalent). At physiological maturity, plants were harvested and P speciation was determined for all plant parts (root, stem, leaf, chaff/pod and seed) and rates of P application, using solution 31P nuclear magnetic resonance (NMR) spectroscopy.Results
Phytate was the dominant form of P in seed whereas orthophosphate was the dominant form of P in other plant parts. The distribution of P species varied with P status for canola but not for wheat. The phytate content of wheat chaff increased from 10 to 45 % of total P as the P rate increased. Canola pods did not show a similar trend, with most P present as orthophosphate.Conclusions
Although minor differences were observed in P speciation across the three P application rates and plant parts, the effect of this on P cycling from residues into soil is likely to be relatively minor in comparison to the overall contribution of these residues to soil P pools. This glasshouse experiment shows the dominant P form in crop residues that is returned to soil after harvest is orthophosphate, regardless of plant P status. 相似文献12.
Nicole M. Hughes Kaylyn L. Carpenter Timothy S. Keidel Charlene N. Miller Matthew N. Waters William K. Smith 《Planta》2014,240(5):971-981
Main conclusion
Anthocyanins in upper (adaxial) leaf tissues provide greater photoprotection than in lower (abaxial) tissues, but also predispose tissues to increased shade acclimation and, consequently, reduced photosynthetic capacity. Abaxial anthocyanins may be a compromise between these costs/benefits. Plants adapted to shaded understory environments often exhibit red/purple anthocyanin pigmentation in lower (abaxial) leaf surfaces, but rarely in upper (adaxial) surfaces. The functional significance of this color pattern in leaves is poorly understood. Here, we test the hypothesis that abaxial anthocyanins protect leaves of understory plants from photo-oxidative stress via light attenuation during periodic exposure to high incident sunlight in the forest understory, without interfering with sunlight capture and photosynthesis during shade conditions. We utilize a cultivar of Colocasia esculenta exhibiting adaxial and abaxial anthocyanin variegation within individual leaves to compare tissues with the following color patterns: green adaxial, green abaxial (GG), green adaxial, red abaxial (GR), red adaxial, green abaxial (RG), and red adaxial, red abaxial (RR). Consistent with a photoprotective function of anthocyanins, tissues exhibited symptoms of increasing photoinhibition in the order (from least to greatest): RR, RG, GR, GG. Anthocyanic tissues also showed symptoms of shade acclimation (higher total chl, lower chl a/b) in the same relative order. Inconsistent with our hypothesis, we did not observe any differences in photosynthetic CO2 uptake under shade conditions between the tissue types. However, GG and GR had significantly (39 %) higher photosynthesis at saturating irradiance (A sat) than RG and RR. Because tissue types did not differ in nitrogen content, these patterns likely reflect differences in resource allocation at the tissue level, with greater nitrogen allocated toward energy processing in GG and GR, and energy capture in RG and RR (consistent with relative sun/shade acclimation). We conclude that abaxial anthocyanins are likely advantageous in understory environments because they provide some photoprotection during high-light exposure, but without the cost of decreased A sat associated with adaxial anthocyanin-induced shade syndrome. 相似文献13.
Wenjuan Huang Juxiu Liu Ying Ping Wang Guoyi Zhou Tianfeng Han Yin Li 《Plant and Soil》2013,364(1-2):181-191
Background and Aims
Phosphorus (P) is commonly one of most limiting nutrients in tropical and subtropical forests, but whether P limitation would be exacerbated during forest succession remains unclear.Methods
Soil phosphatase activity is often used as an indicator of P limitation. Here we examined soil acid phosphatase activity (APA) underneath tree species in pine forest (PF), mixed pine and broadleaf forest (MF) and monsoon evergreen broadleaf forest (MEBF) which represented the early, middle and late successional stages of subtropical forests in China, respectively. We also analyzed other indicators of P status (soil available P and N and P stoichiometry of the tree species).Results
APA or APA per unit soil organic carbon under tree species was relatively low in the early successional forest. Different from PF and MF, soil available P beneath the tree species was lower than in the bulk soils in MEBF. Soil APA was closely related to N:P ratios of tree species across all three forests.Conclusions
Our results imply that P limitation increases during forest succession at our site. The dominant tree species with low soil APAs in MEBF are likely more P-limited than other tree species. 相似文献14.
Katrin Huber Jan Vanderborght Mathieu Javaux Natalie Schröder Ian C. Dodd Harry Vereecken 《Plant and Soil》2014,384(1-2):93-112
Aims
A simulation model to demonstrate that soil water potential can regulate transpiration, by influencing leaf water potential and/or inducing root production of chemical signals that are transported to the leaves.Methods
Signalling impacts on the relationship between soil water potential and transpiration were simulated by coupling a 3D model for water flow in soil, into and through roots (Javaux et al. 2008) with a model for xylem transport of chemicals (produced as a function of local root water potential). Stomatal conductance was regulated by simulated leaf water potential (H) and/or foliar chemical signal concentrations (C; H?+?C). Split-root experiments were simulated by varying transpiration demands and irrigation placement.Results
While regulation of stomatal conductance by chemical transport was unstable and oscillatory, simulated transpiration over time and root water uptake from the two soil compartments were similar for both H and H?+?C regulation. Increased stomatal sensitivity more strongly decreased transpiration, and decreased threshold root water potential (below which a chemical signal is produced) delayed transpiration reduction.Conclusions
Although simulations with H?+?C regulation qualitatively reproduced transpiration of plants exposed to partial rootzone drying (PRD), long-term effects seemed negligible. Moreover, most transpiration responses to PRD could be explained by hydraulic signalling alone. 相似文献15.
Background and aims
The vertical distribution of available phosphorus (P) in the soil is usually heterogeneous with soil depth. However, little is known about the P efficiency of conifer species under vertically heterogeneous low-P conditions. The purpose of this study was to investigate the genetic variations in growth traits and P efficiency of Pinus massoniana, under heterogeneous and homogeneous low-P conditions.Methods
Pot experiments consisting of low-P (a low P level in all soil layers), layered-P (a high P level in the topsoil and a low P level in the bottom soil), and high-P (high P levels in all soil layers) conditions were designed and conducted. Three-way ANOVA was used to investigate genetic variations in P efficiency and the major growth traits under these three types of P conditions.Results
There were substantial genetic variations in the major growth traits, including tree height, stem diameter and seedling dry weight, under both heterogeneous and homogeneous low-P conditions. The heritability for major growth traits was high under both types of low-P condition. Moreover, there were significant genotype × P interaction effects for growth parameters.Conclusions
Our results indicate that it may be possible to select Masson pine genotypes with high P efficiency and productivity. The significant genotype × environment interactions should be exploited in breeding, and genotypes showing specific adaptations to certain nutrient environments should be bred and used within that environment. 相似文献16.
David A. Coomes Warren A. Bentley Andrew J. Tanentzap Larry E. Burrows 《Plant and Soil》2013,367(1-2):77-91
Background and aims
Models of retrogressive succession have emphasised the role of phosphorus (P) depletion in driving biomass loss on surfaces of increasing geologic age, but the influence of impeded drainage on old surfaces has received much less attention. We tested whether poor drainage contributed to changes in ecosystem properties along a 291,000-year chronosequence in New Zealand (the Waitutu chronosequence).Methods
Soil and ecosystem properties were measured at 24 evenly distributed points within each of eight 1.5 ha plots located on young, intermediate and old surfaces. Regression analyses tested whether drainage, in addition to P, affected ecosystem functioning. A complementary fertilization experiment tested whether P was indeed limiting on the most nutrient-depleted sites.Results
Most phosphorus depletion occurred in the early stages of pedogenesis (within 24,000 years), and the older surfaces were similar in soil-P contents, whereas drainage was initially good but became increasingly impeded with surface age. In the fertilizer experiment, species showed positive responses to both nitrogen (N) and P addition on the oldest surfaces, supporting Walker and Syer’s model. However, water table depth was also found to be strongly correlated with plant species composition, forest basal area, light transmission, and litter decomposition when comparisons were made across sites, emphasising that it too has strong influences on ecosystem processes.Conclusions
Poor drainage influences the process of retrogressive succession along the Waitutu chronosequence. We discuss the implications of our work with regard to other chronosequences, suggesting that topography is likely to have strong influences on retrogressive processes. 相似文献17.
Predicting phosphorus bioavailability from high-ash biochars 总被引:4,自引:0,他引:4
Background and aims
Biochars are highly variable in nutrient composition and availability, which are determined by types of feedstock and pyrolysis conditions. The aim of this research was to (a) study the bioavailability of phosphorus (P) in biochars using different feedstocks and pyrolysis conditions; (b) develop a robust chemical method for biochar P availability measurements.Methods
In the present study, (a) chemical analysis – including total P and extractable P (2% citric acid, 2% formic acid, and neutral ammonium citrate extraction), and (b) a bioassay test using rye-grass grown in a P deficient sandy soil were used to compare the P bioavailability of different biochars. Biochars were produced from two different feedstocks (dairy manure-wood mixture, MAe; biosolid-wood mixture, BSe) at four different pyrolysis temperatures (250, 350, 450, and 550°C).Results
Results showed that P in feedstock was fully recovered in the biochars. After 6 harvests, the biochars were as effective as the P fertilizers tested [Sechura phosphate rocks (SPR) and calcium dihydrogen phosphate (CaP)] in increasing the shoot yield. However, P uptake followed the order of CaP >MAe biochars >BSe biochars >SPR, on a same TP basis. Based on the Mitscherlich equation, 2% formic acid was the most sensitive indicator of P bioavailability in biochars.Conclusions
The results suggest that high-ash biochars with high P concentrations are potential P sources with high-agronomic efficiency. We propose the use of 2% formic acid extraction to predict the availability of P in ash-rich biochars. 相似文献18.
Potential phosphorus release from catch crop shoots and roots after freezing-thawing 总被引:1,自引:0,他引:1
Background and aims
Catch crops used for mitigating nutrient losses to water can release phosphorus (P) when exposed to repeated freezing-thawing cycles (FTCs). This study sought to evaluate potential P losses from shoots and roots of eight catch crops.Methods
Shoots and roots sampled from perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), chicory (Cichorium intybus L.), phacelia (Phacelia tanacetifolia L.), red clover (Trifolium pratense L.), white mustard (Sinapis alba L.), oilseed radish (Raphanus sativus var. oleiformis L.) and white radish (R. sativus var. longipinnatus L.) were treated with no freezing, one single FTC, four continuous FTCs and four discontinuous FTCs. All samples were analysed for water-extractable P (WEP), and root samples also for characteristics such as specific root surface area (SSA).Results
Freezing-thawing significantly increased potential P losses from both shoots and roots compared with no freezing. The two radish species and white mustard contained significantly higher concentrations of WEP than the other species, among which chicory and phacelia had the lowest WEP. On average, shoots had 43 % higher WEP than roots. Cumulative P release from shoots and roots was strongly correlated with their total-P content (p?=?0.006 and p?=?0.002, respectively). Cumulative release of P from taproots was correlated with SSA (p?=?0.03).Conclusions
Chicory, and possibly phacelia, appear to be promising catch crops for P. 相似文献19.
Nature and nurture: the importance of seed phosphorus content 总被引:1,自引:0,他引:1
Background
Low phytoavailability of phosphorus (P) limits crop production worldwide. Increasing seed P content can improve plant establishment and increase yields. This is thought to be a consequence of faster initial root growth, which gives seedlings earlier access to growth-limiting resources, such as water and mineral elements. It can be calculated that seed P reserves can sustain maximal growth of cereal seedlings for several weeks after germination, until the plant has three or more leaves and an extensive root system.Case study
In this issue of Plant and Soil, Muhammad Nadeem and colleagues report (1) that measurable P uptake by roots of maize seedlings begins about 5 d after germination, (2) that the commencement of root P uptake is coincident with the transition from carbon heterotrophy to carbon autotrophy, and (3) that neither the timing nor the rate of uptake of exogenous P by the developing root system is influenced by initial seed P content.Hypothesis
Here it is hypothesised that the delay in P acquisition by roots of maize seedlings might be explained if the expression of genes encoding phosphate transporters is not upregulated either (1) because the plant has sufficient P for growth or (2) because a systemic signal from the shoot, which relies on photosynthesis or phloem development, is not produced, translocated or perceived. 相似文献20.