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1.
Plants have adapted a number of mechanisms to cope with widespread phosphorus (P) deficiency in arable lands. Crop species and even cultivars differ widely in one or more of these adaptive mechanisms hence, in P efficiency. Identification of these mechanisms is pre-requisite for long term breeding programs. Two independent experiments were conducted to study the possible mechanisms of P efficiency in Brassica cultivars. Eight Brassica cultivars (‘B.S.A.’, ‘Toria’, ‘Toria Selection’, ‘Brown Raya’, ‘Peela Raya’, ‘Dunkeld’, ‘Rainbow’, and ‘CON-1’) were selected on the basis of differences in growth under P deficiency from preliminary experiment. In the first experiment, cultivars were grown for 40 days in sand supplied either with sparingly soluble phosphate rock (PR) or soluble mono-ammonium phosphate (MAP). Cultivars differed significantly (P<0.05) for biomass production, P contents and P use efficiency. Low P availability in PR treatment resulted in significantly lower dry weights and P contents than those grown with MAP. The cultivars ‘Rainbow’, ‘Brown Raya’ and ‘Dunkeld’ accumulated more biomass (3.2 g/pot) and P contents (3.0 mg/pot) than other cultivars when grown with PR. Root dry weight was significantly correlated with shoot dry weight, shoot P content and total P content (r > 0.65) indicating significance of improved root growth for P acquisition. While in the second experiment cultivars were grown with adequate P for 30 days and then P was withdrawn from the nutrient solution by replacing fresh P free nutrient solution for 10 days. Induced P deficiency increased P contents in young leaves by two folds indicating remobilization of P from older leaves and shoot. Nonetheless cultivars varied for remobilization but differences in P remobilization could not explain the differences in P utilization efficiency among cultivars. Hence further experimentation to study root morphology, P uptake, and organic acid exudation by these cultivars in relation to P deficiency is recommended.  相似文献   

2.
Abstract

Path analysis is a statistical technique that partitions correlations into direct and indirect effects and distinguishes between correlation and causation, whereas correlation in general measures the extent and direction (positive or negative) of a relationship occurring between two or more variables. The estimates of correlation and path coefficients can help us to understand the role and relative contribution of various plant traits in establishing growth behavior of crop cultivars under given environmental conditions. Dependence of shoot dry‐matter (SDM) production of six hydroponically grown Brassica cultivars on various growth parameters and characteristics of P metabolism was investigated using the modified Johnson's nutrient solution to maintain deficient (10 µM) and adequate (200 µM) P levels. Root dry‐matter (RDM), total dry‐matter, P content in shoot, and P‐utilization efficiency (PUE) had significant and positive effects on production of SDM in a P‐deficient environment. Root–shoot ratio (RSR), however, negatively affected SDM of cultivars exposed to P‐deficient conditions and did not show any impact on SDM production in either of the two treatments. In a pot study, six Brassica cultivars were grown in a sandy loam soil that was deficient in NaHCO3‐extractable P (3.9 mg P kg?1 soil) for 49 days. Significant positive correlations were observed between SDM and some other plant traits such as RDM, leaf area per plant, P uptake, and PUE, at both genotypic and phenotypic levels. The correlations of SDM with RSR, however, were not observed, implying that relative partitioning of biomass into roots or shoots had little role to play in SDM production by Brassica cultivars under P‐deficiency stress. Path analysis revealed that favorable impact of RDM and leaf area on SDM production was indirect through positive effect of these parameters on P uptake and PUE. Thus, under P‐deficiency stress, better P acquisition and efficient P utilization by the cultivars for biomass synthesis collectively formed the basis of higher SDM production by the cultivars, evidencing that P uptake and utilization efficiency are two important plant traits for selecting P‐deficiency‐stress‐tolerant Brassica cultivars.  相似文献   

3.
Abstract

Plants grown in highly weathered or highly alkaline calcareous soils often experience phosphorus (P) stress but never a P‐free environment. Thus, applications of mineral P fertilizers are often required to achieve maximum yield, but recovery of applied P fertilizers is notoriously low. Phosphorus deprivation elicits a complex array of morphological, physiological, and biochemical adaptations among plant species and genotypes to enhance P acquisition and utilization efficiency. Ten Brassica cultivars were grown hydroponically to investigate their relative efficiency to utilize deficiently (20‐µM) and adequately (200‐µM) supplied P, using Johnson's modified solution. Cultivars differed significantly (P<0.001) in biomass accumulation. Orthophosphate concentration and uptake in shoot and root, absolute and relative growth rate, and P‐utilization efficiency (PUE) were also significantly different among various Brassica cultivars. Root‐shoot ratio and specific absorption rate were substantially increased in plants subjected to low P supply. Shoot and root dry‐matter yield as well as total biomass production correlated significantly (P<0.01) with their total P uptake and PUE. Cultivars, which were efficient in P utilization, were also efficient accumulators of biomass under adequate as well as deficient levels of P supply. As part of the study, kinetic parameters of P uptake were evaluated for six contrasting Brassica cultivars in PUE, grown in nutrient solution. The kinetic parameters related to P influx were maximal transport rate (Vmax), the Michaelis–Menten constant (Km), and the external concentration when net uptake is zero (Cmin). Lower Km and Cmin values were indicative of P‐uptake ability of the cultivars, evidencing their adaptability to P‐stress conditions. In another experiment, six cultivars were exposed to no P nutrition for 27 days after initial feeding on optimum nutrition for 14 days. All the cultivars retranslocated P from aboveground parts to their roots during growth in P‐free conditions, the magnitude of which was variable in different cultivars. Phosphorus concentration at 41 days after transplanting was higher in developing leaves than developed leaves. Translocation of absorbed P from metabolically inactive sites to active sites in plants growing under P‐stress conditions may have helped the tolerant cultivars to establish a better rooting system, which provided basis for tolerance against P‐deficiency stress and increased PUE.  相似文献   

4.
Genotypic variation in nitrogen (N) efficiency of rapeseed is caused by differences in reproductive growth. This might be related to genotypic variation in sulfur (S) utilization. In this study it was tested if S deficiency in growing plant parts is induced under N-limiting conditions due to high sulfate accumulation in mature leaves which is poorly remobilized. Leaf S remobilization was compared under high and low N supply in four rapeseed cultivars that were grown in hydroponics with leaf-senescence induction by shading. Low N conditions did not increase sulfate accumulation in mature leaves. Total S remobilization from the leaves was higher under N-limiting than N-sufficient conditions. The proposed S deficiency in young plant parts therefore may not be more probable under low than under high N conditions. However, genotypic variation in S uptake and remobilization was found under N-limiting conditions only and might therefore contribute to genotypic variation in reproductive growth.  相似文献   

5.
Abstract

Enhancing the phosphorus (P) use efficiency is critical for the sustainable cultivation of winter wheat. In this study, we investigated the effects of P fertilization level on plant P-uptake and agronomic traits under deficit irrigation, by using two wheat cultivars sharing contrasting water responses (i.e., Jimai 585 and Shimai 22). The high P level treatment (P120) improved plant biomass and P accumulation at each growth stage, grain yields, P remobilization amount to grain (PRA), P remobilization rate (PRR), and P contribution rate (PRR) of the cultivars with respect to the low P treatments (i.e., P90 and P60). Compared with Jimai 585, a cultivar acclimated to affluent water, the drought tolerant cultivar Shimai 22 exhibited similar behaviors on plant biomass, P-associated traits at each stage, and agronomic traits at maturity under P120. However, Shimai 22 was more improvement on P-associated and agronomic traits than Jimai 585 under P60 and P90. P contents were increased whereas moisture contents decreased in soil profile treated by P120 with respect to those by P60. Meanwhile, the soil profile cultivated by Shimai 22 displayed reduced moisture and P contents under P deprivation (i.e., P90 and P60) respect to that by Jimai 585, suggesting the contribution of more consumption of soil P and water storage to improved agronomic traits of Shimai 22. Together, our investigation suggested that suitable P input management positively mediates plant P-associated traits and grain formation capacity under deficit irrigation by improving supply and internal translocation of P across tissues in winter wheat plants.  相似文献   

6.
【目的】探讨不同磷效率紫花苜蓿(Medicago sativa L.)叶片光合性能对低磷胁迫的响应,从光能转化和利用的差异来揭示品种适应磷胁迫的机理。【方法】试验采用砂培法,供试材料为2个磷高效紫花苜蓿品种甘农6号(G6)、极光(JG)和2个磷低效品种Bara 310SC (B310)、甘农4号(G4)。以1/4霍格兰营养液为基础,设置磷浓度为0.5 mmol/L (正常对照)和0.05 mmol/L (低磷)两个处理水平,紫花苜蓿幼苗处理30天后,测定苜蓿幼苗叶片叶绿素荧光参数,将样品烘干后,测定生物量和磷含量。【结果】与对照相比,低磷胁迫下4个苜蓿品种的生物量和磷利用效率均降低,相对可变荧光诱导曲线J点和I点的荧光强度上升,初级醌受体(QA)被还原的最大速率(Mo)显著增加,受体库容量(Sm)等参数下降,PSⅡ受体侧受损;活性反应中心数目(RC/CSo)降低,光能的吸收(ABS/RC、ABS/CSo)、捕获(TRo/RC、TRo/CSo)、传递(ETo...  相似文献   

7.
Copper (Cu) deficiency in grain crops grown on the Canadian Prairie has increased recently, while nearly 50% of the soils have low available phosphorus (P) levels. This study was conducted to quantify the variation in Cu and P uptake among some common Canadian wheat (Triticum aestivum L.) cultivars due to the effects of nitrogen (N) fertilizer and the environment. The effects of N fertilizer application at 0,50, and 100 kg N ha‐1 and seeding in early May or mid‐May on the P and Cu contents of four wheat cultivars were determined in an experiment conducted over two years at Fort Vermilion (58°24'N, 116°0’ W). Cultivar and N fertilizer produced similar variances in P concentration. Phosphorus uptake was increased by N fertilizer, but was not affected by the cultivars tested. Nitrogen fertilizer produced four times as much variability in Cu concentration and uptake as did the effect of genotypes. Date of sowing within the recommended time frame had no effect on plant P and Cu contents. There was no treatment interaction effect on plant P or Cu content. In a second experiment, situated near Grande Prairie (55°10'N, 118°48'W) and conducted over two years, P and Cu uptake and concentrations were determined for 10 agronomically diverse spring wheat cultivars. The range was 1.2‐ to 1.4‐fold for P and 1.5‐ to 1.7‐fold for Cu concentration. Plant Cu, but not plant P, was correlated with grain yield (r=0.64 to 0.86), suggesting that either varietal differences in Cu uptake may affect yield or prior selection for yield may have resulted in the selection for Cu‐efficient plants as well. Environmental, i.e., site‐year, effects on plant P, and particularly Cu concentrations, were larger than the varietal effects in both studies. These studies indicate that selection of Canadian wheat cultivars should be based on their yield potential rather than their efficiency in Cu or P uptake since crop nutrition can be more readily managed by optimal fertilization.  相似文献   

8.
Magnesium (Mg) is known as one of the mobile elements and can move from the lower to upper leaf blade when the plants suffer from Mg deficiency. It is generally recognized that symptoms of Mg deficiency appear on lower leaves. This study was conducted to reveal the effect of Mg deficiency stress on remobilization of Mg and nitrogen in banana plant and to collect the typical symptoms of Mg deficiency. Quartz sand cultures were used to study the effect of Mg deficiency on banana growth and its mobilization and allocation in the plants. Results showed that chlorosis, a typical symptom of Mg deficiency, occurs in the second leaf from top of banana plant after 35 days of Mg deficiency. Necrosis of the whole leaf in the middle part of banana and a significant reduction of leaf area from the top to middle leaves are detected. However, older leaves remain green, and their area is not affected. Mg is more stable in the banana plant and cannot be remobilized and transported from the old to young leaves under Mg deficiency. After 195 days of Mg deficiency, the growth and Mg nutrition of Mg-deficient plant can be normalized by the restoration of Mg nutrient after 49 days of deficiency. Therefore, Mg in banana leaves is not mobile and reusable from older to younger leaves.  相似文献   

9.
Wild relatives of wheat may possess useful traits or genes for efficient use of nitrogen (N) or phosphorus (P). Forty-three wheat addition lines with alien chromosomes from Leymus, Agropyron, Hordeum, Psathyrostachys, Aegilops, and Secale cereale, along with their common parent Chinese Spring (CS) were cultured by hydroponics, and their phenotypic variation, N/P uptake and utilization efficiency were investigated at seedling stage. The phenotypic variation showed that N deficiency decreased plant height, shoot dry weight, and total dry weight, while increased root length, number of leaves, SPAD value, and root to shoot ratio (R/S); while P deficiency decreased all the measured traits except root dry weight and R/S. Aegilops longissima 2S and Aegilops searsii 4SS addition lines were identified as both N- and P-efficient germplasm, of which Ae. longissima 2S addition line showed significant increased N and P uptake efficiency than CS under all treatments.  相似文献   

10.
Abstract

In this study, the effects of boron (B) and calcium (Ca) supply on Ca fractionation in suspension cells and different tissues of rape (Brassica napus L.) plants of two cultivars with different B efficiency were studied, with a purpose to elucidate the mechanism by which B affects Ca concentration in plants. As Ca supply increased in nutrient solution or culture medium, the relatively easily extractable Ca fractions, that is H2O and 80% ethanol extractable Ca in leaves, 1 mol L?1 NaCl extractable Ca in upper leaves, roots and suspension‐cell were significantly increased. While the recalcitrant Ca fractions extracted by 2% acetic acid, 0.6 mol L?1 HCl and Ca in the residue were not affected by Ca supply. Increasing B supply in nutrient solution or culture media significantly reduced 1 mol L?1NaCl extracted Ca in suspension cell and roots of both cultivars, which were most likely related to the alteration of cell wall metabolism. Calcium extracted by 2% acetic acid, 0.6 mol L?1 HCl and Ca in residue in suspension‐cell and roots of B inefficient cultivar Bakow were easily improved by B deficiency as compared to that of B efficient cultivar Tezao16. Increasing of these relative recalcitrant Ca fractions was related to the different response of cultivars to the B deficiency, which may reflected different extent that Ca deposited in the two cultivars due to impaired membrane integrity under B deficiency. The effects of B on Ca concentration in lower and upper leaves of the two cultivars were quite different and were the integrated effects of B on Ca metabolism, Ca transport in plants and growth of certain organ. Increasing B supply increased total Ca concentration in upper leaves of Bakow and reduced that of Tezao16, which might relate to the different adaptability of the two cultivars to comparatively higher B supply.  相似文献   

11.
水培法磷矿石对小麦生长的影响   总被引：1，自引：0，他引：1  
Screening cultivars to grow under conditions of low phosphorus (P) availability and utilize P efficiently from compounds of low solubility in soils may be beneficial to overcome poor plant growth in P-deficient soils.The growth behavior and P utilization efficiency of seven wheat cultivars grown in hydroponics were studied,using rock phosphate as P source.The wheat cultivars grown for 30 days were significantly different in biomass accumulation,P uptake and P utilization efficiency.The dry matter production of all the cultivars was significantly correlated with P uptake,which in turn correlated to the drop in the root medium pH.The ranking of wheat cultivars on the basis of dry matter yield,P uptake and P utilization efficiency was Zamindar 80 ＞ Yccora ＞ C 271 ＞ WL 711 ＞ Barani 83 ＞ PARI 73 ＞ Rohtas.The cultivar Zamindar 80 appeared to possess the best growth potential in P-deficient soils.  相似文献   

12.
Primary determinants of crop production in arid/semiarid regions are lack of moisture and infertility, especially phosphorus (P) deficiency or unavailability. The effects of P and water stress (WS) levels on shoot and root dry matter (DM), leaf area, root volume, total root length, and shoot and root P concentrations and contents were determined in two bean [Phaseolus acutifolius Gray, cv ‘Tepary #21’ ("drought‐resistant") and P. vulgaris L., cv “Emerson’ ("drought‐sensitive")] and two sorghum [Sorghum bicolor (L.) Moench, cv SA7078 ("drought‐resistant") and ‘Redlan’ ("drought‐sensitive")] cultivars grown in nutrient solution. Plants were grown with different levels of P (20 and 100 μM for bean and 20, 80, and 160 μM for sorghum) when seedlings were transferred to nutrient solution, and WS levels of 0, 13.8, and 1 6.4% polyethylene glycol (PEG‐8000) introduced after plants had grown in solution 23 days (bean) and 31 days (sorghum). All growth traits were lower when bean and sorghum plants were grown with WS and low P. Growth traits were higher in cultivars grown with high compared to low P regardless of WS. Root P concentration and content and shoot content, but not shoot P concentration, were lower when bean plants were grown with WS compared to without WS. Tepary #21 bean had higher shoot DM, leaf area, total root length, and shoot P concentration than Emerson when plants were grown with WS at each level of P. Sorghum shoot and root P concentrations were higher as P level increased regardless of WS, and WS had little effect on shoot P concentration, but root P concentration was higher. Contents of P were similar for SA7078 and Redlan regardless of P or WS treatment, but SA7078 had greater P contents than Redlan over all P and WS treatments. “Drought‐resistant”; cultivars generally had better growth traits, especially total and specific root lengths, than “drought‐sensitive”; cultivars.  相似文献   

13.
Increased phosphorus (P) efficiency is needed to sustain agriculture productivity on soils with low available P. Significant differences were found among Brassica cultivars for growth, P utilization, and remobilization under P deficiency (see our companion paper, Aziz et al., 2011a). To identify the possible mechanisms of P acquisition from low soluble P compounds, four cultivars (‘Rainbow’, ‘CON-1’, ‘Dunkeld’, and ‘Peela Raya’) were selected to ascertain the relationship of their differential P acquisition and growth with their root length in soil and with organic acid release pattern in solution culture experiments. For this purpose their growth and P acquisition from phosphate rock (PR) was compared with calcium di-hydrogen phosphate (Ca-P) when adding uniform dose of 100 mg P kg?1 soil separately from the two sources. Biomass accumulation, root length, root fineness, plant P uptake and ash alkalinity was significantly (P < 0.01) different in plants of all the four cultivars when supplied with PR or Ca-P in soil. Minimum biomass produced by ‘Peela Raya’ grown with either P source was followed by ‘CON-1’, ‘Dunkeld’, and ‘Rainbow’ in ascending order. Shoot dry matter production had a significant positive correlation with root dry matter production (r = 0.85, P < 0.01), root length (r = 0.59, P < 0.05) and root P uptake (r = 0.95, P < 0.01). Cultivars varied significantly for organic acid secretion in solution culture experiment. Higher quantities of secreted citric acid, malic acid and tartaric acid in solution culture experiment were measured for ‘Rainbow’ and ‘Dunkeld’ cultivars. Efficient performance of these two cultivars for growth and P uptake was associated with their longer roots and more secretion of organic acids especially citric acid.  相似文献   

14.
Abstract

The large variation in phosphorus acquisition efficiency of different crops provides opportunities for screening crop species that perform well on low phosphorus (P) soil. To explain the differences in P efficiency of winter maize (Zea mays L.), wheat (Triticum aestivum L.), and chickpea (Cicer arietinum L.), a green house pot experiment was conducted by using P‐deficient Typic ustochrept loamy sand soil (0.5 M NaHCO3‐extractable P 4.9 mg kg?1, pH 7.5, and organic carbon 2.7 g kg?1) treated with 0, 30, and 60 mg P kg?1 soil. Under P deficiency conditions, winter maize produced 76% of its maximum shoot dry weight (SDW) with 0.2% P in shoot, whereas chickpea and wheat produced about 30% of their maximum SDW with more than 0.25% P in shoot. Root length (RL) of winter maize, wheat, and chickpea were 83, 48, and 19% of their maximum RL, respectively. Considering relative shoot yield as a measure of efficiency, winter maize was more P efficient than wheat and chickpea. Winter maize had lower RL/SDW ratio than that of wheat, but it was more P efficient because it could maintain 2.2 times higher P influx even under P deficiency conditions. In addition, winter maize had low internal P requirement and 3.3 times higher shoot demand (i.e., higher amount of shoot produced per cm of root per second). Even though chickpea had 1.2 times higher P influx than winter maize, it was less P efficient because of few roots (i.e., less RL per unit SDW). Nutrient uptake model (NST 3.0) calculations satisfactorily predicted P influxes by all the three crops under sufficient P supply conditions (CLi 48 µM), and the calculated values of P influx were 81–99% of the measured values. However, in no‐P treatment (CLi 3.9 µM), under prediction of measured P influx indicated the importance of root exudates and/or mycorrhizae that increase P solubility in the rhizosphere. Sensitivity analysis showed that in low P soils, the initial soil solution P concentration (CLi) was the most sensitive factor controlling P influx in all the three crops.  相似文献   

15.
A large proportion of phosphate fertilizer applied to calcareous soils reacts with calcium. Changes in soil phosphorus (P) availability after single application of biochar and phosphate-solubilizing bacteria have been reported. However, interaction of biochar (increasing soil pH) and phosphate-solubilizing bacteria (decreasing soil pH) on P availability in calcareous soil is not well known. An incubation experiment was conducted to study how the interactive effects of biochars (produced from wheat straw and cow manure at 300°C and 500°C with residence time of 1, 3 and 6 h) at different rates (0, 5 and 10 t ha?1) and phosphate-solubilizing Pseudomonas sp. IS8b2 affected on content of soil available P after 0, 60, 120 and 180 days of incubation (DOI) in a calcareous soil. After 60 DOI, the maximum value of available P (50.31 mg kg?1) was observed in the compound treatment of Pseudomonas sp. IS8b2 and wheat straw biochar (10 t ha?1) produced at 500°C with residence time of 3 h. We conclude that the combination use of wheat straw biochar and phosphate-solubilizing bacterium is promising to potentially improve soil P availability in calcareous soil, but further research at field scale is needed to confirm this.  相似文献   

16.
In an attempt to evaluate whether breeding and selection for high yielding capacity changed the P requirement of modem wheat cultivars. the response of two wheat cultivars to different levels of P supply was investigated. A traditional cultivar (‘Peragis’) and a modern spring-wheat cultivar (‘Cosir’) were cultivated in a C-loess low in available P and high in CaCO3 in 120 cm high PVC tubes. In addition and for comparison, nutrient solution experiments were also conducted. Shoot growth, root growth. P uptake. P translocation and P distribution within the shoot at different developmental stages were compared. The grain yield of the modern cultivar ‘Cosir’ was higher at limiting and non-limiting P supply and. therefore, this cultivar can be considered as more P-efficient than the traditional cultivar. Grain yield reduction at low P supply was mainly due to an inhibition of tillering and thus lower number of ears per plant, whereas the number of grains per ear was hardly affected. Reduced tillering at low P supply could not be related to P concentrations in the shoot meristematic tissues which were generally much higher than in other plant tissues and kept at an elevated level even at limiting P supply. Root branching (1st order laterals) was reduced at limiting P supply in ‘Cosir’ but not in ‘Peragis’ which, generally, had lower numbers of laterals at the beginning of tillering. From the results it can be concluded that the main factors contributing to the higher P efficiency of the modern cultivar ‘Cosir’ are (i) efficient use of assimilates for root-growth characteristics which enhance P acquisition: enhanced root branching and thus smaller mean root diameter and longer root hairs, (ii) an efficient P uptake system, (iii) efficient remobilization of P from vegetative plant organs to the grains, and most importantly (iv) lower P requirement for grain yield formation because of lower ear number per plant but higher grain number per ear.  相似文献   

17.
Grain phosphorus (P) and phytate contents are important for early growth and quality of wheat, respectively. We studied seed P and phytate contents of 57 wheat genotypes released during last 6 decades. The grain total P and phytate P concentrations ranged from 2.0 to 8.9 mg g?1 and 1.6 to 4.7 mg g?1, respectively. Grain P was higher in genotypes released in current or last decade than pre-green revolution period and it correlated well with grain phytate contents. Indicating that breeders worked only for increased grain P and did not consider the phytate contents. Twenty-five genotypes were selected based on differences in grain P and phytate contents to observe the P use efficiency under field conditions. Genotypes differed significantly for grain P and yield at both 0 and 60 kg ha?1 P levels. In conclusion, phytate fraction in grains of recent wheat genotypes was more as compared to old genotypes and genotype Inqlab-91 and Chakwal-86 had maximum grain total P. Moreover, number of productive tillers, spikelet per spike, grain weight, harvest index and grain P concentration and uptake were found responsible for P tolerance under P deficiency.  相似文献   

18.
ABSTRACT

Soil compaction interferes in soil nutrient transport and root growth. The aim of this work was to evaluate eucalypt growth and phosphorus (P) nutritional efficiency as affected by soil compaction and P rates. The treatments were composed of a 3 × 4 factorial scheme (soil bulk densities levels versus P fertilization rates) for two weathered tropical soils, a clayey Ferralsol (FClayey) and a sandy Ferralsol (FSandy). The soil bulk densities assessed were 0.90, 1.10 and 1.30 g cm?3 for FClayey, and 1.35, 1.55 and 1.75 g cm?3 for FSandy. The P rates were 0, 150, 300 and 600 mg kg?1 for FClayey, and 0, 100, 200 and 400 mg kg?1 for FSandy. Soil compaction reduced root growth, P content in the plant, P utilization efficiency and P recovery efficiency; and increased average root diameter. Phosphorus fertilization increased root length density, root surface area, dry matter, P content in the plant, P utilization efficiency and P uptake efficiency; and decreased P recovery efficiency. It was concluded that P fertilization is not effective to offset the deleterious effects of soil compaction on eucalypt growth and nutrition.

Abbreviations: FClayey: clayey Ferralsol; FSandy: sandy Ferralsol; RDens: root length density; RDiam: root diameter; RSurf: root surface area; RDM: root dry matter; SDM: shoot dry matter; WPDM: whole-plant dry matter; RP: root P content; SP: shoot P content; WPP: whole-plant P content; PUtE: P utilization efficiency; PUpE: P uptake efficiency; PRE: P recovery efficiency.  相似文献   

19.
Phosphate rock (PR) was activated via acidulation with HCl, EDTA, and oxalic acid to enhance its reactivity. The release, lateral transport, and uptake of phosphorus (P) along with trace metals from pristine and activated PRs were investigated in a soil micro-block system over a period of 27 days, using wheat (Triticum aestivum L.) plants. Significantly (p < 0.05) higher amounts of available soil P, Fe, Mn, and Zn were released from all the PRs after application to soil within first 9 days of seedling transplantation, while the release of other trace metals (Cd, Co, Cr, Cu, Ni, and Pb) was minimal (<1.2 mg kg?1). On cumulative basis, APR-O (oxalic acid activated PR) was the most efficient amendment releasing 164% more available P, followed by APR-E (EDTA activated PR) releasing 130% more available P, compared to the pristine PR. Similar results were also observed in the release of available Fe, Mn, Zn, and other trace metals. The highest diffusive mass fluxes for available P, Mn, Fe, and Zn in soil were observed after 3 days of seedling transplantation, which reduced subsequently. The uptake of P, Fe, Mn, and Zn by wheat plants was increased by 394%, 715%, 92%, and 91%, respectively, in APR-O application compared to the pristine PR, while it was increased by 280%, 188%, 16%, and 27%, respectively, in APR-E application compared to the pristine PR. Subsequently, APR-O and APR-E amendments resulted in enhanced shoot lengths, root lengths, shoot dry matter, and root dry matter contents of wheat plants. Hence, it was concluded that activation of PR with oxalic acid and EDTA prior to direct soil application may enhance the reactivity of PR and could serve as a cost-effect fertilization strategy for higher wheat crop production.  相似文献   

20.
The phosphorus (P) and potassium (K) accumulation patterns of canola (Brassica napus L.) are poorly understood, although such information is essential for determining optimal P‐ and K‐fertilizer strategies. This study investigated the patterns of P and K uptake and distribution among plant organs of three early or midmaturing canola cultivars (Tribune, Trigold, and Boomer) differing in K efficiency compared to wheat (Triticum aestivum L. cv. Nyabing). Plants were grown in a glasshouse with nonlimiting P and K supply and harvested at eight growth stages until maturity. Maximum P accumulation by all canola cultivars occurred during late flowering (GS 5,5; 84 d after sowing), whereas P accumulation in wheat plants peaked just prior to anthesis (Z59; 73 d after sowing). Maximum accumulation of K in canola cultivars Tribune and Trigold occurred 73 d after sowing (GS 4,8), but peaked earlier (61 d after sowing) in Boomer canola (GS 4,2) and Nyabing wheat (Z55). The results highlight the importance of early P and K supply to both species; however, the extended uptake of P and K by the canola cultivars Trigold and Tribune compared to wheat suggests that availability of soil P or K postflowering may be of more importance to canola than to wheat.  相似文献   

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