Effects of liming on phosphate availability in acid soils

Summary The critical factors involved in the plant-soil-phosphorus-lime interaction are outlined and discussed. Conflicting reports suggest that the prior liming of highly weathered acid soils can result in an increase, a decrease, or no change in the availability of applied phosphate. Adsorption of phosphate by amphoteric soil surfaces generally decreases slowly as the pH is raised from 4.0 to 7.0. However, in soils initially high in exchangeable Al³⁺, liming results in the formation of new, highly active, phosphate adsorbing surfaces as the Al³⁺ ions precipitate as insoluble polymeric hydroxy-Al cation species. Thus, if an acid soil is reacted with lime and then phosphate, without intervening air drying, liming can increase phosphate adsorption. If the same limed soil is air dried before reaction with phosphate (e.g. adsorption isotherm studies), liming decreases phosphate adsorption. Apparently, air drying alters the surface characteristics of recently limed soils, probably by promoting the crystallization of the hydroxy-Al cation polymers as gibbsite.An important phenomenon, which is often overlooked, is that liming can increase phosphate availability by stimulating mineralization of soil organic phosphorus. However, at high soil pH values, the precipitation of insoluble calcium phosphates can decrease phosphate availability. Since Al toxicity is characterised by the inhibition of the uptake, translocation and utilization of phosphate by plants, liming often increases the utilization of soil phosphate by plants through amelioration of Al toxicity.When making lime recommendations or interpreting the data collected from lime-phosphate experiments, it is important to consider all the complex interacting soil and plant factors involved.     

Sustainable phosphorous management in two different soil series of Pakistan by evaluating dynamics of phosphatic fertilizer source

Phosphorous (P) plays the prominent role to promote the plants storage functions and structural roles, as it is recognized as a vital component of ADP, ATP, Cell wall as well as a part of DNA. Soils acts as the sink to supply P to plants because soil pH and its physical condition are the main factor which regulate the solubility and availability P element. Phosphorus is not deficient in Pakistani soils but its availability to plants is the serious matter of concern. A pot experiment was conducted to evaluate P dynamics in two different soil series of Pakistan (Bahawalpur and Lyallpur) using Maize as test crop. The treatments applied were T0: Control (without any fertilizer), T1: Recommended DAP @648 mg pot^?1, T2: Half dose DAP @324 mg pot^?1, T3: Recommended rate of TSP @900 mg pot^?1, T4: Half dose TSP @450 mg pot^?1. Soil analysis showed that Bahawalpur soil has sandy clay loam texture with 33% clay and Lyallpur series has sandy loam texture with 15.5% clay; furthermore, these soil contain 4.6 and 2.12% CaCO₃ respectively. Results showed an increase in P concentration in roots (23 mg kg^?1) with the application of half dose of TSP in Lyallpur series and lowest in Bahawalpur series (14.6 mg kg^?1) at recommended dose of DAP. Concentration of P in shoots responded the same; increase at half dose of TSP (16.7 mg kg^?1) and lowest at full dose of DAP in Bahawalpur series as (15.58 mg kg^?1). Adsorbed P (17 mg kg^?1) was recorded highest in Bahawalpur soil with more clay amount in pot with DAP application but lower in Lyallpur soil series (14 mg kg^?1) with the application of applied TSP. The PUE was recorded highest in Lyallpur series with the application of half dose of TSP and it was 61% more than control and was Highest in Bahawalpur series was with the application of recommended dose of DAP is 72% more than control treatment. On estimation; results showed that applied sources made an increase in P availability than control, but TSP gave better P uptake than DAP unless of rates applied. Soil of Lyallpur series showed better uptake of P and response to applied fertilizers than Bahawalpur series which showed more adsorption of P by high clay and CaCO₃ amount. Conclusively, the study suggested that soil series play a crucial role in choosing fertilizer source for field application.     

Regulation of phosphate influx in barley roots: Effects of phosphate deprivation and reduction of influx with provision of orthophosphate

Barley plants were grown in nutrient solutions, which were maintained at either 0 (-P) or 15 μ M orthophosphate (+P). After 11 days phosphate influx into the intact roots of the -P plants began to increase by comparison with +P plants. During this period differences became apparent between the treatments in absolute growth rates, as well as in the root:shoot ratios. Phosphate influx in the -P plants continued to increase as a function of time, to a maximum value of 2.4 μmol (g fresh wt)^-1h^-1 at 16 days after germination. This rate was 6 times higher than influx values for +P plants of the same age. During the period of enhanced uptake phosphate was strongly correlated (r²= 0.77) with root organic phosphate concentration. – The enhancement of inorganic phosphate influx into intact roots of -P plants was rapidly reduced by the provision of 15 μ M orthophosphate. Typically, within 4 h of exposure to this concentration of phosphate, influx values fell from 1.80 ± 0.20 to 0.75 ± 0.03 μmol (g fresh wt)^-1 h^-1, while inorganic phosphate concentrations of the roots increased from 0.12 to 1.15 μmol (g fresh wt)^-1 during the same period. Hill plots of the influx data obtained during this period, treating root inorganic phosphate as an inhibitor of influx, gave Hill coefficients close to 2. The rapidity of the reduction of influx associated with increased root inorganic phosphate together with the Hill plot data provide evidence for an allosteric inhibition of influx by internal inorganic phosphate.     

光照对水环境变化和沉积物吸收磷酸盐的影响

在富氧和缺氧环境下室内模拟研究光照对清洁湖区沉积物吸收磷酸盐和对上覆水质变化的影响.结果表明,光照使缺氧环境上覆水体中的pH值显著提高,并增加其溶解氧的含量.上覆水体中磷酸盐浓度的变化在实验初期主要受水-沉积物界面溶解氧含量的影响,表现为富氧组磷酸盐的浓度下降迅速,但随实验时间的推移,光照逐渐起主要作用,表现为实验结束时有光条件下的磷酸盐浓度明显低于无光条件,磷酸盐的减少量和减少速度明显高于无光条件.无论是富氧、缺氧,还是有光、无光,当上覆水体中磷酸盐的浓度很高时,沉积物都能够吸收磷酸盐,但吸收量各不相同.光照对沉积物吸收上覆水中溶解性无机磷酸盐(DIP)的影响受缺氧和富氧环境的限制.     

The distribution of phosphate over iron-bound and calcium-bound phosphate in stratified sediments

Release of phosphate from, and adsorption ontosediments is calculated as a chemical equilibriumbetween dissolved o-phosphate and two solidphosphates, i.e. iron- and calcium-bound phosphate.Organic phosphates play a minor role, if any at all.Using chemical equilibrium equations, the distributionof the two solid inorganic phosphates is calculatedfrom the accumulated phosphate quantity as function oftime and depth in sediment layers of shallow lakes orwetlands. It is shown that this distribution dependson water depth, pH, Ca²⁺ concentration in thewater, Fe(OOH) concentration in the sediments andmaximal binding capacity of the sediments. Bycomparing values of dissolved phosphate at differentpH values, it is shown that acidification, whichusually takes place in hypolimnia, will cause releaseof phosphate, which is not necessarily dependent onthe redox potential. The release does depend on pH,Ca²⁺ concentration in the water, CaCO₃concentration in the sediments and the saturationstage of the two P-pools in the surface layers ofthese sediments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of fertilization and cutting on the chemical composition of vegetation and soils of mountain heathlands in Spain

Abstract. In the mountains of northern Spain, patches dominated by Calluna vulgaris are scarce and they may disappear or change as a result of continued lack of management and possibly increasing nutrient availability through atmospheric deposition. The effects in the soil properties and in the composition of Calluna vulgaris and Erica tetralix shoots on heathlands dominated by Calluna and Erica subjected to fertilization and experimental cutting were studied in three mountain passes in northern Spain. A total of 90 1‐m² plots received different combinations of cutting and twice the estimated atmospheric deposition of nitrogen (5.6 g.m^?2.yr^?1) as ammonium nitrate. One of the dominant ericaceous species (Calluna and Erica) was selectively cut by hand at ground level and their nitrogen shoot content were compared in the presence or absence of the other. Treatments were carried out in April 1998. In each plot one soil sample was taken in the original situation and 12, 24 and 36 months after the treatments. Soil properties such as organic matter, total nitrogen, available phosphorus and pH were determined. In every plot five shoots of Calluna and Erica were also taken to analyse total nitrogen content in the original situation and 12, 24 and 36 mo after the treatments. Nitrogen addition does not necessarily lead to increased levels in the soil, and a clear pattern was not found in the three areas. A gradual decrease in available phosphorus content was detected in the three areas until two years after treatment, although values tend to recover in two of the areas in the third study year. An increase in organic matter content was observed in all areas. It is concluded that increased nutrients alone, at twice the rate of the estimated current atmospheric deposition for the area, which is relatively low, will not alter significantly the soil characteristics of the mountain heathland stands. A clear increase in plant N‐content is observed in the fertilized plots in comparison with the non‐fertilized ones and Calluna always has higher nitrogen content than Erica. This increase is most pronounced one year after the treatments started in one of the areas and after two years in the other two areas. In some cases the elimination of one species is seen to favour nitrogen increase in the other.     

覆盖与间作对亚热带丘陵茶园地温时空变化的影响

研究了亚热带丘陵茶园连续4年进行稻草覆盖与白三叶草间作对茶园地温时空动态变化的影响.结果表明,茶园地温具有明显的时空动态变化特征和位相滞后现象,与茶树的年生长发育周期各阶段的最适温度非常吻合.稻草覆盖与白三叶草间作改变了土壤热量交换层（地表层）的性质,具有升温时降温和降温时增温、保温的双向动态调控作用,降低了日较差,增强了同一土层温度的稳定性,其调控效果为随着土壤深度增加而降低,13：00>19：00>7：00,降温大于增温和保温,降温幅度随气温的升高而增大,增温和保温随气温的下降而加强,间作白三叶草的降温效果大于稻草覆盖,保温效果则相反.茶园地温时空变化转换点得到调节,显著地降低了有害高温的出现次数,明显地降低了持续高温期的土壤温度,有效地缩短了极限高温时间.     

原生动物与解磷微生物协同解磷作用

磷是农业生产重要的限制因素之一,土壤生物包括原生动物和微生物在土壤磷素转化过程中起着重要的作用。通过纯培养和土壤培养试验发现,供试的原生动物能够提高磷矿粉的有效磷,土壤有效磷含量也显著增加。所溶解出来的磷很大一部分以无机磷酸盐的形式贮藏在细胞内,熏蒸时才释放出来,少部分磷转化为生物量磷。原生动物与解磷菌之间没有显著的相互促进作用。     

Influence of aluminium on phosphate and calcium uptake in beech (Fagus sylvatica) grown in nutrient solution and soil solution

The effects of AICI₃ on uptake of Ca²⁺ and phosphate in roots of intact beech ( Fagus sylvatica L. provenance Maramures) plants were studied in nutrient solution and soil solution. Aluminium reduced the concentrations of Ca, Mg and P in plants and increased that of K. In short term experiments, uptake of Ca²⁺(⁴⁵Ca) was reduced by exposure of the roots to Al. The effect of aluminium on Ca²⁺(⁴⁵Ca) uptake was immediate and primarily of a competitive nature, preventing Ca²⁺ from being adsorbed. Uptake of ³²P-phosphate increased with increasing Al concentration up to 0.1 m M and then decreased at higher Al concentrations. The effect of Al on ³²P-phosphate uptake was most pronounced during the first hours of exposure. Growth of plants for 15 days in soil solution, collected from the upper A horizon of a beech forest soil, had no effect on uptake of Ca²⁺(⁴⁵Ca) and ³²P-phosphate, probably because of a low concentration of labile bound monomeric Al and binding of Al to organic compounds. Soil solution from the deeper B horizon reduced Ca²⁺(⁴⁵Ca) uptake and increased ³²P-phosphate uptake in a manner similar to that with Altreatment in nutrient solution. It is concluded that in soil solution from the deeper regions of the soil, mineral uptake by roots was affected by Al.     

Molecular cloning and functional analysis of a H+-dependent phosphate transporter gene from the ectomycorrhizal fungus Boletus edulis in southwest China

Phosphate transporters (PTs), as entry points for phosphorus (P) in organisms, are involved in a number of P nutrition processes such as phosphate uptake, transport, and transfer. In the study, a PT gene 1632 bp long (named BePT) was cloned, identified, and functionally characterized from Boletus edulis. BePT was expected to encode a polypeptide with 543 amino acid residues. The BePT polypeptide belonged to the major facilitator superfamily and showed a high degree of sequence identity to the Pht1 family. A topology model revealed that BePT exhibited 12 transmembrane helices, divided into two halves, and connected by a large hydrophilic loop in the middle. A yeast mutant complementation analysis suggested that BePT was a functional PT which mediated orthophosphate uptake of yeast at micromolar concentrations. Green fluorescent protein–BePT fusion proteins expressed were extensively restricted to the plasma membrane in BePT transformed yeast, and its activity was dependent on electrochemical membrane potential. In vitro, quantitative PCR confirmed that the expression of BePT was significantly upregulated at lower phosphorus availability, which may enhance phosphate uptake and transport under phosphate starvation. Our results suggest that BePT plays a key role in phosphate acquisition in the ectomycorrhizal fungus B. edulis.     

Derepression of the high-affinity phosphate uptake in the yeast Saccharomyces cerevisiae

Phosphate starvation derepresses a high-affinity phosphate uptake system in Saccharomyces cerevisiae strain A294, while in the same time the low-affinity phosphate uptake system disappears. The protein synthesis inhibitor cycloheximide prevents the derepression, but has no effect as soon as the high-affinity system is fully derepressed. Two other protein synthesis inhibitors, lomofungin and 8-hydroxyquinoline, were found to interfere also with the low-affinity system and with Rb⁺ uptake. After incubation of the yeast cells in the presence of phosphate the high-affinity system is not derepressed, but the $\text{V}{}_{\mathrm{<mtext>max</mtext>}}$ of the low-affinity system has decreased for about 35%. Phosphate supplement after derepression causes the high-affinity system to disappear to a certain extent while in the meantime the low-affinity system reappears. The results are compared with those found in the yeast Candida tropicalis for phosphate uptake.     

Functional biology of plant phosphate uptake at root and mycorrhiza interfaces

Phosphorus (P) is an essential plant nutrient and one of the most limiting in natural habitats as well as in agricultural production world-wide. The control of P acquisition efficiency and its subsequent uptake and translocation in vascular plants is complex. The physiological role of key cellular structures in plant P uptake and underlying molecular mechanisms are discussed in this review, with emphasis on phosphate transport across the cellular membrane at the root and arbuscular-mycorrhizal (AM) interfaces. The tools of molecular genetics have facilitated novel approaches and provided one of the major driving forces in the investigation of the basic transport mechanisms underlying plant P nutrition. Genetic engineering holds the potential to modify the system in a targeted way at the root-soil or AM symbiotic interface. Such approaches should assist in the breeding of crop plants that exhibit improved P acquisition efficiency and thus require lower inputs of P fertilizer for optimal growth. Whether engineering of P transport systems can contribute to enhanced P uptake will be discussed.     

Effect of salt on survival and P-solubilization potential of phosphate solubilizing microorganisms from salt affected soils

A total of 23 phosphate solubilizing bacteria (PSB) and 35 phosphate solubilizing fungi (PSF) were isolated from 19 samples of salt affected soils. The ability of 12 selected PSB and PSF to grow and solubilize tricalcium phosphate in the presence of different concentrations of NaCl was examined. Among 12 PSB, Aerococcus sp. strain PSBCRG₁-1 recorded the highest (12.15) log viable cell count at 0.4 M NaCl concentration after 7 days after incubation (DAI) and the lowest log cell count (1.39) was recorded by Pseudomonas aeruginosa strain PSBI₃-1 at 2.0 M NaCl concentration after 24 h of incubation. Highest mycelial dry weight irrespective of NaCl concentrations was recorded by the Aspergillus terreus strain PSFCRG₂-1 (0.567 g). The percent P_i release, in general, was found to increase with increase in NaCl concentration up to 0.8 M for bacterial solubilization and declined thereafter. At 15 DAI, strain Aerococcus sp. strain PSBCRG₁-1 irrespective of NaCl concentrations showed the maximum P-solubilization (12.12%) which was significantly superior over all other isolates. The amount of P_i released in general among PSF was found to decrease with increase in NaCl concentration at all the incubation periods. Aspergillus sp. strain PSFNRH-2 (20.81%) recorded the maximum P_i release irrespective of the NaCl concentrations and was significantly superior over all other PSF at 7 DAI.     

Potassium content in soil,uptake in plants and the potassium balance in three European long-term field experiments

This study quantitatively assesses the fate of K derived from mineral fertilizers and organic manures and the effective K balance in three long-term field experiments at Rothamsted (UK), Bad Lauchstaedt (Germany) and Skierniewice (Poland). Plant availability, uptake and the overall utilization of K over the last 30 years (1965–1996) are discussed and related to soil K Availability Indices determined by the standard methods used in each of the three countries. In addition, to provide a standard comparison of the three sites, Exchangeable K (1 M NH₄OAc) and Non-exchangeable K (K extracted by boiling with 1 M HNO₃) were measured on one recent (1995) set of soil samples. Plant availability and utilization of K was partly related to clay content, but more closely to the cation exchange surfaces associated with both mineral and organic constituents and also, at Rothamsted, to the capacity of clay minerals to fix K. The recovery rate of K from mineral fertilizer by crops did not exceed 62%. Fertilizers were least effective in the most strongly K fixing soil at Rothamsted (44% maximum) and most effective in the soil with the highest cation exchange capacity (CEC) at Bad Lauchstaedt (62%), where the greater quantity of exchange sites appear to be associated with humic material. Recoveries of K from farmyard manure (FYM) varied from 22–117% (values of >100% indicating subsoil uptake or the release of reserves). Deficiencies of N, P and Mg in some treatments decreased the effectiveness of applied K and may have caused increased leaching of K from the plough layer. FYM was generally more effective than mineral fertilizer where mineral N and P were not applied because these nutrients were effectively supplied in the manure. But the effectiveness of mineral K fertilizer decreased when applied in combination with FYM because FYM was the preferred source of K. Where FYM application increased the CEC of soils, this also improved K utilization but only where K was not extensively leached or fixed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of pH,phosphate and ammonia on the rate of uptake of nitrate and ammonia by freshwater phytoplankton

The effect of phosphate (PO₄ ⁺³) and pH in regulating nitrate (NO₃) and ammonia (NH₃ ⁺) uptake by phytoplankton was investigated in two Oklahoma lakes using ¹⁵N tracers. Addition of PO₄ ⁺³ above ambient concentrations had a negligible effect on the rate of uptake of NO₃ ^– or NH₃ ⁺. Manipulation of pH of lake water had little effect on uptake of either NO₃ ^– or NH₃ ⁺. A correlation analysis suggested that NO₃ ^– is not used by phytoplankton when NH₃ ⁺ concentrations exceed about 210 µg NH₃ ⁺-N(1)^–1.     

Effects of vegetation and fertilizer on metal and Sb plant uptake in a calcareous shooting range soil

Shooting range soils frequently contain anomalous concentrations of metals (e.g. Pb, Zn, Mn) and Sb coming from bullets which may be released into the environment. In a pot experiment, we investigated metal and Sb uptake by three plant species (Plantago lanceolata, Lolium perenne and Triticum aestivum) growing on a calcareous shooting range soil (pH 7.8; 500 mg kg⁻¹ Pb, 21 mg kg⁻¹ Sb) and the uptake changes when an acidic fertilizer solution was applied to the soil. Metal and Sb solubility in the soil was determined by extraction with 0.1 M NaNO₃. In addition, we measured pH, electrical conductivity and dissolved organic carbon in drainage samples. The results showed significant increase over time of pH (from 7.8 to 8.3) and decrease of electrical conductivity and dissolved organic carbon (from 230 to ∼130 mg L⁻¹). Fertilizer application increased NaNO₃-extractable Pb and Sb and root:shoot biomass ratio but not plant metal uptake. In T. aestivum spikes accumulated more Zn, Ni and Cu than shoots and grains. Mn and Zb uptake was correlated in L. perenne shoots. P. lanceolata, a Sb-bioindicator, did not accumulate high amounts of Sb (<1 mg kg⁻¹).     

Effect of phosphorus supply on phosphate uptake and alkaline phosphatase activity in Rhizobia

The effect of P nutrition on phosphate uptake and alkaline phosphatase activity was studied in chemostat culture for four rhizobial and three bradyrhizobial species. Phosphate-limited cells took up phosphate 10- to 180-fold faster than phosphate-rich cells. The four fast-growing rhizobial strains contained high levels of alkaline phosphatase activity under P-limited conditions compared to the repressed levels found in P-rich cells; alkaline phosphatase activity could not be detected in three slow-growing rhizobial strains, regardless of their P-status.Glycerol 1-phosphate-uptake in the cowpea Rhizobium NGR234 was derepressed over 50-fold under P-limited conditions, and appeared to be co-regulated with phosphate uptake.The phosphate-uptake system appeared similar in all strains with apparent K _m values ranging from 1.6 M to 6.0 M phosphate and maximum activities from 17.2 to 126 nmol · min^-1 · (mg dry weight of cells)^-1. Carbonyl cyanide m-chlorophenyl hydrazone strongly inhibited phosphate uptake in all strains and a number of other metabolic inhibitors also decreased phosphate uptake in the cowpea Rhizobium NGR234. The phosphate uptake system in all strains failed to catalyse exchange of ³²P label in preloaded cells or efflux of phosphate. The results suggest a single, repressible, unidirectional and energy-dependent system for the transport of phosphate into rhizobia.Abbreviations CCCP carbonyl cyanide m-chlorophenylhydrazone - DCCD N,N-dicyclohexylcarbodiimide - HEPES N-2-hydroxyethyl-piperazine-N-2-ethanesulphonic acid     

长期施加氮肥及氧化钙调节对酸性土壤硝化作用及氨氧化微生物的影响

以长期施加氮肥及添加氧化钙调节的酸性土壤为研究对象,运用定量PCR和DGGE技术,探讨了土壤氨氧化微生物及硝化作用对不同施肥处理及氧化钙调节的响应。长期施化学氮肥导致酸性土壤p H(KCl)值(3.35—3.47)和硝化潜势(0.02—0.14μg NO-2-N g-1土壤h-1)进一步降低,而添加Ca O后土壤酸化得以缓解(p H值4.10—4.46),土壤硝化潜势(0.22—0.34μg NO-2-N g-1土h-1)显著增加。同时,添加Ca O处理对氨氧化古菌(AOA)的群落结构无明显影响,但明显提高了各施肥处理土壤中氨氧化细菌(AOB)的群落多样性,加Ca O处理的土壤中,AOA的数量降低而AOB的数量增加。这些结果表明虽然酸性土壤中AOA在数量和活性上占主导优势,AOB在功能上冗余,但当添加Ca O后,AOA和AOB对环境变化迅速作出响应,并根据其不同的生态位需求重新分配优势地位,二者交替作用共同驱动酸性土壤硝化作用。     

The effect of indigenous vesicular-arbuscular mycorrhizal fungi on nutrient uptake and growth of barley in two Danish soils

Summary To investigate the effect of indigenous VAM fungi and of increasing the amount of natural inoculum barley was grown in containers buried in the field with uninoculated and inoculated irradiated soil and with uninoculated and inoculated untreated soil from two locations, one low and one high in available P. The experiment was set up with 3 P fertilizer applications (0, 15, 30 kg P/ha). Growth and uptake of P was measured. The inocula were prepared from natural VAM populations. VAM fungal infection was established in the irradiated soil at a lower level than in the untreated soil. VAM fungal infection was decreased by increasing P fertilizer application. In the soil low in available P VAM increased concentration of P and total uptake of P. VAM did not cause an increased growth. The reason for this may be the low establishment of VAM in the irradiated soil and/or because the indigenous VAM species were not efficient. It is also possible that a pronounced growth increase due to irradiation the soil may have masked a smaller effect of the indigenous VAM fungi. Increasing the amount of natural inoculum in the untreated soil influenced neither VAM frequency nor growth.     

玉米花生间作和磷肥对间作花生光合特性及产量的影响

揭示玉米(Zea mays)和花生(Arachis hypogaea)间作提高花生对弱光利用能力的光合特点及磷(P)肥效应, 对阐明间作花生适应弱光的光合机理和提高间作花生的产量具有重要意义。该试验于2011-2012年在河南科技大学试验农场分析了间作花生功能叶的叶绿素含量与构成、光响应曲线和CO₂响应曲线特点和荧光参数。结果表明: 与单作花生相比, 施P与不施P条件下玉米和花生间作显著(p < 0.01)提高了花生功能叶的叶绿素b含量, 降低了叶绿素a/b, 显著提高了光系统II最大光化学效率(F_v/F_m)、实际光化学效率(Φ_PSII)、光化学猝灭系数(q_P)、表观量子效率(AQY)和弱光时的光合速率, 显著降低了气孔导度、二磷酸核酮糖羧化酶羧化速率(V_cmax)、电子传递速率(J_max)和磷酸丙糖利用速率(TPU); 与不施P相比, 施P有利于提高间作花生功能叶的叶绿素含量, 显著提高了Φ_PSII、q_P、V_cmax、J_max和TPU, 说明间作花生通过提高功能叶的叶绿素b含量, 改变叶绿素构成, 提高了光系统II的F_v/F_m、Φ_PSII和q_P, 增强了对光能的捕获和转化能力, 提高了对弱光的利用能力, 而并非提高了对CO₂的羧化固定能力; 施P有利于提高间作花生对弱光的利用能力和产量, 土地当量比提高了6.2%-9.3%。