Sorghum genotype differences in phosphorus uptake rate and distribution in plant parts

Relatively low amounts of the phosphorus (P) added to soils is recovered by plants. Many plants show differences in their ability to take up and use P, but the mechanisms for these differences are not fully understood. The purpose of this study was to determine differences among sorghum [Sorghum bicolor (L.) Moench] genotypes for P uptake rates and distribution in plant parts.

Differences in P uptake rates were determined for six sorghum genotypes at 24, 38, and 52 days of age at three P levels. Larger differences were noted among genotypes in 24‐day‐old plants than for older plants. Uptake rates were 6‐ to 14‐times higher (dependent on genotype) in 24‐day‐old plants than in 52‐day‐old plants. NB9040 which had the highest dry matter yield at each age had the lowest rate of P uptake, and CK60‐Korgi which had the lowest dry matter yield at each age had the highest rate of P uptake.

Only small differences were noted among genotypes for distribution of P within plant parts for younger plants. Older plants showed differences in P distribution, and NB9040 translocated more P from lower to upper leaves, had higher efficiency ratios (dry matter produced/unit P), and had a larger root system than CK60‐Korgi.

The sorghum genotypes that produced more dry matter under low P conditions had lower uptake rates of P and had the ability to distribute P from older to younger developing tissues. When grown in soils, plants that have lower P uptake rates, greater ability to distribute P, and larger root systems may not deplete P from soil solutions as rapidly, could explore more soil, and possibly use P more efficiently than plants that do not possess these traits.     

Sulfur nutrition effects on dinitrogen fixation of seedling alfalfa

Greenhouse experiments with alfalfa (Medicago sativa L. cv. ‘Apollo') were performed to evaluate the effect of varied nutrient solution concentrations of S on the yield, nodulation, dinitrogen fixation, N and S concentration, and the partitioning of N and S into shoots and roots.

Sulfur treatments consisted of four levels (0, 1, 2.5, and 25 mg S/L) of added S. The experimental design was a randomized complete block, with three replications. Seeds were inoculated with commercial inoculum, planted in plastic containers of acid‐washed sand, and irrigated with nutrient solution for one minute, at 2 h intervals.

Sulfur application increased the yield of all treatments. The results demonstrated that the addition of 2.5 mg S/L to the nutrient solution, besides providing the highest total dry matter yield (12 g/72 plants), showed the highest percent yield increase (19%), acetylene reduction rate (0.426 umole ethylene/mg nodule dry wt/h), total N content (306 mg/72 plants), percent recovery of S (3.8%), and percent increase in N due to dinitrogen fixation (32%).

N:S ratios obtained were different for shoots and roots, with S application decreasing the N:S ratios. The N:S ratios of 16:1 (shoots), and 9:1 (roots) obtained in the 2.5 mg S/L treatment were found to be adequate for normal growth and development.

These data indicated that the 2.5 mg S/L treatment (2.7 mg total S/L) was optimal for alfalfa seedling development.     

Elemental leaf content and deficiency symptoms in rabbiteye blueberries: 1. Nitrogen

Rabbiteye blueberries grown in sand culture were subjected to varying levels of N fertilization (0 ‐ 81 mg N/liter) applied in aqueous solution at the rate of 250 ml/plant daily. Essential elements other than N were kept constant. Shoot growth and leaf concentration of N, P, K, Mg, Ca, Mn, Fe, Cu, B, Zn, Co, and Al were determined. Shoot growth and percent leaf N increased with increased N levels. Shoot growth increased little at N fertilization levels of 0 ‐ 9 mg/ liter but increased rapidly at higher rates. N content in leaves followed a quadratic curve, with % N in leaves increasing more rapidly from 0 to 27 mg N/liter than from 27 to 81 mg N/liter fertilization levels. Leaf concentration of K, Ca, Mg, Mn, B, and Ca decreased linearly as N levels increased. Total content of all elements increased as N fertilization increased. Visual N deficiency became increasingly evident as % N content decreased below 1.4% N.

Nitrogen, the most utilized element in plants, is usually the first to become deficient in sandy soils low in nutrient content (1). Rabbiteye blueberries (Vaccinium ashei Reade) are often grown on acidic, sandy, upland coastal plains soils that are low in cation exchange capacity, organic matter content, and available nutrients. In these acidic soils, NH₄N is more available than in neutral soils (2). The NH₄N source appears to be more suitable for blueberry growth, resulting in greater nutrient uptake, plant growth, and % N of leaf tissue than did the NO₃N sources (5,6).

Nitrogen deficiency symptoms in rabbiteye blueberries are characterized by small, yellow and/or red leaves and stunted plants (3). Since young rabbiteye plants are very sensitive to fertilizer, similar chlorosis symptoms (yellowing or reddening of leaves) can be associated with over‐fertilization, possibly due to root damage (7). Cain (2) found that leaves from healthy container‐grown highbush (V. corymbosum L.) blueberry plants contained about 2% N and higher levels of K and Ca than field‐grown plants. Greenhouse and Field studies indicate that leaf N content in rabbiteye blueberries is usually lower, ranging from about 1.5 to 1.8 (3,7,8). Increased N fertilization decreased the nutrient uptake of other essential elements (Ca and Mg) in rabbiteye blueberries (6). In highbush, Popenoe (4) indicated that a depression of P and K might occur under conditions of high N levels.

This study was initiated to ascertain the effect of NH₄N fertilization levels on uptake patterns of essential elements and to determine the relationships of N fertilization, leaf N content, plant growth, and visible deficiency symptoms.     

Influence of ferredoxin levels on nitrate reductase activity in iron deficient lemon leaves

The relationship between nitrate reductase activity and ferredoxin levels in lemon tree leaves was studied. The experiments were carried out on leaves from full‐nutrient sufficient trees as the reference, and on leaves from trees with several nutritional stresses, mainly iron chlorosis from trees growing under Fe‐stressed conditions.

Iron deficiency reduced leaf ferredoxin concentration and consequently decreased nitrate reductase activity. Fe(II) infiltration treatments of intact leaves, as well as several incubation assays, permit to deduce the dependence of the enzymatic nitrate reduction of the leaf ferredoxin levels.     

Effect of nitrogen and sulphur fertilizers and seed inoculation with rhizobium phaseoli on the nitrogen‐sulphur relationships of bean (phaseolus vulgaris L.)

A greenhouse experiment with beans (Phaseolus vulgaris L.) was performed in order to investigate the effect of nitrogen and sulphur application and seed inoculation on the yield, leaf area, distribution of different nitrogen and sulphur fractions and N/S ratio in shoot, fruit and root.

Inoculation of plants together with nitrogen or sulphur application produces an increase in the concentration of total nitrogen and a decrease in the accumulation of nitrate‐nitrogen and sulphate‐sulphur in shoot, fruit and root. Leaf area increased more with nitrogen than with sulphur application while the highest amounts of fruit dry matter were obtained with sulphur application.

N: S ratios obtained were different according to the part of the plant tested. Sulphur fertilization decreased the N: S ratios in shoot, fruit and root. The data obtained indicate that and adequate N: S ratio can insure maximum production of yield.     

Effects of solution pH on the growth and chemical composition of rice plants

Rice plants were grown in solution culture for a period of five weeks at pH's ranging from 3.5 to 8.5. Maximum dry matter was obtained at pH 5.5, but substantial reductions in the growth of tops and roots were observed at pH's of 3.5 and 8.5. At pH 3.5, both leaves and roots were short and unhealthy. The roots were thickened with lateral root growth severely inhibited. At pH 8.5, the youngest leaves developed chlorotic symptoms with roots being coarse and discoloured.

Plant concentrations of essential elements were adequate for normal plant growth at pH 5.5. Iron concentration in plant tops substantially decreased with increase in solution pH, but a reverse trend was observed for roots. The concentrations of other elements progressively increased in plant tops and roots with increasing pH.     

Distribution of magnesium between chlorophyll and other photosynthetic functions in magnesium deficient “sun”; and “shade”; leaves of poplar

Photosynthesis of attached sun and shade grown leaves of poplar (Populus euramericana (Dode) Guinier cv. ‘Robusta') has been measured at 0.03 and 0.5% CO₂ at light limitation and light saturation. Photosynthetic rates were compared for plants grown at normal and low Mg‐supply and related to leaf Mg content.

Photosynthetic rates at high CO₂ level were affected at Mg concentration lower than about 50 μmoles/g dry leaf tissue at both photosynthetic irradiations. This was paralleled by a decrease in chlorophyll concentration. At a low CO₂ level photosynthesis was affected at the same Mg concentration but the degree of the inhibition was higher. This indicates that synthesis of chlorophyll as well as CO₂ fixation are affected at the same “critical”; Mg concentration.

Shade leaves contain more chlorophyll per unit leaf weight than sun leaves but the percentual‐ decrease of chlorophyll in Mg deficient leaves Is similar for sun and shade leaves at the same Mg leaf concentration. As a consequence, in Mg deficient shade leaves extraordinary high portions of leaf Mg are bound to chlorophyll (up to 57%; in contrast: up to 37% in sun leaves).     

Manganese toxicity in bush bean as affected by concentration of manganese and iron in the nutrient solution

An experiment was conducted to clarify the relationship between Mn toxicity and Fe deficiency in bush snap bean (Phaseolus vulgaris L. cv. ‘Wonder Crop No. 2'). Seedlings were grown in full strength Hoagland No. 2 solution at pH 6.0 for ten days. Six concentrations of Mn as MnCl₂.4H₂O were used in combination with three concentrations of Fe as FeEDTA.

Toxicity symptoms, induced by low levels of Mn (0.1 ppm and above), included: small brown necrotic spots and veinal necrosis on primary leaves; necrosis on primary leaf petioles; interveinal chlorosis, with or without brown necrotic spots, on trifoliate leaves; and brown necrotic spots on stipules. Manganese toxicity symptoms were alleviated or prevented by increasing Fe concentration in the nutrient solution.

Manganese concentration in the leaves increased with increasing Mn and decreased with increasing Fe concentration in the nutrient solution, Iron concentration in the roots increased with increasing Fe concentration in the nutrient solution; however, Fe concentration in the leaves was not significantly affected by increasing Mn concentration in the solution culture. Manganese toxicity symptoms developed when Mn concentration in the leaves reached about 120 ppm.

A decrease in the Fe/Mn ratio in the nutrient solution resulted in a proportionate decrease in that of the leaves. Manganese toxicity symptoms occurred when the Fe/Mn ratio in the solution was 10.0 and below, or when the ratio in the leaves was less than 1.5. The ratio of Fe/Mn in the solution required for optimum growth of ‘Wonder Crop No. 2’ bean, without Mn toxicity symptoms, was in the range of 20.0 to 25.0.

Results indicate that the chlorosis on bush bean leaves induced by excessive Mn in the nutrient solution was due to excessive accumulation of Mn and not to Fe deficiency.     

Volatile losses of sulfur by intact alfalfa plants

An apparatus was developed for the quantitative collection of volatile sulfur compounds released by intact plants and was used to study the effects of leaf temperature and stomatal aperture on the amount and pattern of release.

An air stream sweeps volatiles released by the plants through a water‐cooled condenser system in which the air is dried prior to trapping the volatile sulfur compounds on activated carbon. Tests with ³⁵S‐labelled 1‐butanethiol gave a mean recovery of 95.8 ± 4.3%.

The yield of volatile sulfur compounds increased greatly when air flow rate increased from 1 to 2 1 min^‐1 , but was independent of flow rate over the range 2 to 6 1 min^‐1. About 93% of the trapped activity originated from plant shoots, about 1% from stem bases and roots and about 4% from culture solutions.

Release of volatile sulfur compounds from intact plants followed a diurnal pattern, maximum rates occurring around midday and minimum rates overnight. Maximum rates of release ranged from 30 to 41 ng S g dry weight of shoots^‐1 2 hr ^‐1, while minimum rates ranged from 1.5 to 2.1 ng S g dry weight of shoots^‐1 2hr^‐1. Leaf temperature rather than stomatal aperture seemed to be the major factor controlling rate of release of volatile sulfur compounds. The rate of release was almost doubled by an increase of 7–9°C in leaf temperature.     

Elemental leaf content and deficiency symptoms in rabbiteye blueberries: 2. Calcium and magnesium

In separate tests, rabbiteye blueberries (Vaccinium ashei Reade) grown in sand culture were subjected to varying levels of Ca (0–81 mg/liter) and Mg (0–24 mg/liter) applied at rates of 250 ml/plant daily. Other essential nutrients were kept constant. Leaf concentrations of N, P, K, Mg, Ca, Mn, Fe, Cu, B, Zn, Co, and Al were determined. The concentration of Ca in the leaves increased linearly but that of Cu decreased in response to increasing levels of Ca fertilization. Leaf concentrations of other elements were not significantly influenced by Ca fertilization. Leaf Mg and Al concentrations increased linearly in response to increasing levels of Mg fertilization. The P content in leaves followed a quadratic curve with increased Mg fertilization. Percent P increased from the 0 to 12 mg/liter levels and then decreased from the 12 to 24 mg/liter levels of Mg. High levels of Mg fertilization resulted in reduced Cu content of leaves.

Fertilization rates of Ca or Mg had little effect on shoot dry weight except at the 0 mg/liter levels. As leaf Ca decreased below 0.20% Ca, Ca deficiency symptoms became more prevalent. Magnesium deficiency symptoms increased as leaf Mg decreased below 0.15% Mg.     

Balance and turnover of nutrients in a bamboo plantation (Bambusa bambos) of different ages

The accumulation of nutrients by a bamboo plantation and their rate of uptake and release through litter fall was determined. The nutrients in the above-ground living biomass increased linearly with plant age. The balance of nutrients showed an increase in loss by litter fall, and annual nutrient accumulation and enrichment ratio were enhanced with age. Annual percentage turnover showed no consistent trend. Enrichment ratios were in the order of K>N>Mg>Ca>P. In conclusion, precautions are necessary during the exploitation of bamboo plantations on a large scale in order to prevent nutrient depletion of the soil. Received: 7 January 1996     

Incidence of P,Mn and B deficiencies on the levels of the whole and individual flavonoid groups in tomato leaves

Alterations occur in the normal content of total and individual flavonoids with P, Mn and B deficiencies, in tomato leaves.

P and Mn deficiencies do not alter the total flavonoid level. Nevertheless, these deficiencies lead to different contributions of each flavonoid group (flavonols, flavones and flavanones) to the whole content.

B deficiency produces a very significant increase in total flavonoid content. Compounds that contribute the most to this accumulation are flavones.     

Differential tolerance of bush bean cultivars to excess manganese in solution and sand culture

Nineteen bush bean cultivars were screened for tolerance to excess Mn in nutrient solution and sand culture experiments. Seven‐day‐old seedlings were treated with full strength Hoagland No. 2 nutrient solution containing different Mn concentrations for 12 days in the greenhouse.

Cultivars showing the greatest sensitivity to Mn toxicity were ‘Wonder Crop 1’ and ‘Wonder Crop 2'; those showing the greatest tolerance were ‘Green Lord’, ‘Red Kidney’ and ‘Edogawa Black Seeded’.

Leaf Mn concentration of plants grown in sand culture was higher than that for plants grown in solution culture. The lowest leaf Mn concentration at which Mn toxicity symptoms developed, was higher in tolerant than in sensitive cultivars. The Fe/Mn ratio in the leaves at which Mn toxicity symptoms developed, was higher in the sensitive cultivars than in the tolerant ones.

We concluded that Mn tolerance in certain bush bean cultivars is due to a greater ability to tolerate a high level of Mn accumulation in the leaves.     

Selecting for nutrient use efficiency within forage grass species: I. Development of a screening system

One means of achieving increased forage grass production on infertile soils is to select plant genotypes which grow efficiently at low levels of available nutrients. This requires methods to identify variability in individual plant nutrient response from among large populations of plants grown under controlled environmental conditions.

A compact, containerized system, partially developed for growing large numbers of forage grass seedlings for use in automatic machine transplanter research, was adapted as the basis for such a screening technique. Three trials were made with 100‐plant samples of a kleingrass‐75 (Panicum coloratum L.) population to test the utility of the system. Results of these trials showed that differences in nutrient use efficiency (= reciprocal of nutrient concentration in the plant tissue, or milligrams dry matter produced per milligram nutrient absorbed) among the grass plants could be effectively identified by using the system in conjunction with laboratory analysis of the material grown. Plants could be maintained in vigorous condition during several harvest periods, and those selections that were retained could be easily transplanted for further propagation and evaluation.     

Soil organic carbon balance and nutrients (NPK) availability under treated wastewater irrigation for bioenergy sorghum production in an arid ecosystem

This column study evaluated the effects of irrigation with two water qualities (WW and FW) to produce bioenergy sorghum on SOC balance, nutrients availability and salt constituents in two soils (TX and NM) amended with gypsum & elemental sulfur (S) and un-amended. Study results indicated that SOC concentration was higher in freshwater irrigated columns (7.41 g kg^?1) than wastewater irrigated soils (7.32 g kg^?1) across growth year-soil type-amendments-depth. Soils amended with gypsum and sulfur registered significantly higher value of 7.52 and 7.41 g kg^?1 compared to 7.30 and 7.23 g kg^?1 in non-amended soils under fresh and wastewater irrigation, respectively. Lower SOC in WW irrigated columns could be due to the combined effects of increased salinity and priming effects. Although SOC content initially increased in gypsum and S amended soils to about 10g kg^?1, at the end of the study SOC in all treatments decreased to levels significantly below the pre-study. WW irrigation added 2.00, 1.10 and 4.40 times the N, P and K added by fertilizers and was able to meet 65%, 87%, and 210% of bioenergy sorghum uptake of respective nutrients. Sulfates and chlorides of sodium and calcium were dominant salts, which significantly affected SOC and nutrients.

Abbreviations: FW: freshwater; WW: treated wastewater; G + S: gypsum and elemental sulfur; NA: no amendment, TX: Texas soil and NM: New Mexico soil     

Ameliorative effect of selenium on tomato plants grown under salinity stress

The ability of selenium (Se) to counteract salt inhibitory effects in crop plants, especially in tomato, is still poorly documented. In order to examine the impact of Se addition on the growth, some biochemical parameters related to osmotic adjustment and antioxidant defense of salt-stressed tomato, a two-factorial experiment was conducted in a greenhouse. The plants were supplied with NaCl (0, 25, or 50 mM) and Se (0, 5, or 10 μM), individually or simultaneously. The results showed that salinity had a deleterious impact on plant biomass and physiological parameters studied. The application of Se alleviated this adverse effect by improving the integrity of cell membranes and by increasing leaf relative water content under stress conditions. Moreover, the application of 10 μM Se significantly increased the photosynthetic pigments concentration under salt stress. Salt stress also caused an inhibition of catalase activity, but its activity was restored in the presence of Se. The free radical scavenging activity significantly increased in plants subjected to 25 mM NaCl and supplied with 5 µM Se, compared to NaCl-alone treatment. Both physiological and biochemical results indicate that 10 µM Se treatment can increase plant performance under salt stress, especially under high NaCl concentration.

Abbreviations: CAT: catalase; Chl: chlorophyll; DPPH: 2,2-diphenyl-1-picrylhydrazyl; DW: dry weight; FW: fresh weight; POD: peroxidase; REL: relative electrolyte leakage; RWC: relative water content; free radical scavenging activity (FRSA); TW: turgid weight     

Phosphorus uptake rate and growth characteristics of wheat roots 1

Phosphorus uptake by plant roots is influenced by the plant root properties and solution P supply characteristics. These properties included (i) the relation between nutrient concentration and uptake rate, (ii) the change in uptake rate with plant age and with root age.

Information on the size of nutrient flux values and their change with increasing plant age can be used to determine the nutrient levels needed in the soil to supply nutrients rapidly enough to the root surface to minimize deficiencies. The objective of this research was to determine the relation between plant age and P absorption properties and root growth characteristics of wheat (Triticum vulgare L.) cv. Era.

Wheat was grown for periods up to 42 days in solution culture in a controlled climate chamber. Sequential harvests were made and P uptake and root morphology were measured. Shoot growth was exponential with time to 32 days and linear thereafter. Root dry weights increased linearly with time at a slower rate than shoot dry weights. Root length increased logarithmically with time (r² = 0.95; log y = 0.069x + 1.85).

With increasing plant age there was a reduction in average P uptake rate by wheat roots.     

Effects of N‐source,light intensity and temperature on nitrogen metabolism of bahiagrass

Under greenhouse conditions, a study was made on the effects of nitrogen (N) source (N)O₃ or NH₄), mode of application (single vs. split) and nitrification inhibition on the N‐uptake and metabolism, of bahiagrass.

Variations in light and temperature in the greenhouse affected the N‐metabolism of bahiagrass plants. Nitrate fed plants had nitrate reductase activity (NRA) pattern different from that of NH₄‐fed plants. Amino‐N accumulation patterns were similar for plants under both N‐sources, although amino‐N levels in leaves of NH₄‐fed plants were much smaller than that of NO₃ plants. Nitrate accumulation in leaves showed inverse trend to that of roots in plants fed both NO₃ or NH₄. To the sharp peaks in NO₃ levels in roots due to increases in light and temperature corresponds a sharp decrease of its levels in leaves.

For both both NO₃ or NH₄ treatments, soluble‐N accumulated most in the rhizomes of bahiagrass plants, whereas protein N accumulated most in leaves, suggesting that rhizomes had a buffering effect on the NO₃ fluxes to leaves. This presumably resulted in a lag in the NRA response of the NO₃‐fed plants to increases in light and temperature.     

Aluminum effects on uptake and translocation of nitrogen in sorghum (Sorghum bicolor,L. Moench)

The effects of aluminum on the uptake and translocation of N in two hybrid cultivars of sorghum with differential tolerance to aluminum were studied.

Aluminum decreased the amount of N accumulated and the % of N in the aerial parts of the plants. In the roots the amount of N accumulated also decreased but the % of N increased, in both cultivars. Besides an effect on dry matter yield, Al probably reduces the uptake of N and its translocation to the aerial parts of the plant. Apparently, this impairment on N translocation resulted from Al effects on the root pressure.

Aluminum not only reduced the amount of N translocated but also changed the sap composition. The % of NO₃ ‐N decreased while the % of amino acid‐N increased suggesting an Al effect on N uptake and also on protein degradation. Asparagine and glutamine contributed about 80% of the free amino acid fraction; however, their proportions changed in presence of Al. Therefore, Al also interfered with the synthesis and/or interconversion of these amino acids.     

Effect of Boron on Antioxidant Response of Two Lentil (Lens culinaris) Cultivars

Boron (B) is an essential micronutrient for plants through paticipating key reactions such as reproduction, development, and regeneration. Similar to its deficiency, its over-concentations possess toxic effects on plant growth. In this work, possible boron toxicity was researched through evaluating alaterations in antioxidant enzymes, oxidative stress biomarkers, and chlorophyll contents for two types of lentil species as red (native) and green (winter flake 11) lentil (Lens culinaris L.cv) cultivars, which are indigenous to Turkey. Ten days old seedling lentil plants were subjected to low as 0.5, 1.0 mM and high 2.0 and 5.0 mM boric acid treatments for 7 days. B worked as a growth-promoting nutrient for 0.5, 1.0, and 2.0 mM concentration by enhancing length and weight of both shoot and root tissues, while it started showed its suppression effect on these tissues at 5-mM cocentration, which were obtained more dramatic for green lentil in comparison to red lentil. In contrast to this, oxidative stress markers such as MDA, H₂O₂, and proline concentrations showed increasing trend for 0.5, 1.0, 2.0, and 5.0 mM B treatment, accompanied with a change in photosynthetic pigment concentrations (p < 0.01). MDA in red lentil shoot control was 30,3871 (μmol/gFW) and it was significantly increased to 36,5806 and 51,7414 by the 2.0 and 5.0 B rates, respectively. However, enzymes in anti-oxidation metabolism include superoxide dismutase (SOD), guaiacol peroxidase (GPX), lipoxygenase (LOX), glutathione peroxidase (GSH-Px) activities were obtained higher in high-B-treated groups, while decreased and stable activities were obtained for catalase (CAT) and ascorbate peroxidase (APX) enzymes. CAT and APX activities were higher than those were obtained for 2.0 and 5.0 mM B treatments in both root and shoot tissues. The lentil species manipulated their metabolism to suppress B-stress, and enhanced growth in shoot and root tissues up to 5-mM B stress even though oxidative stress markers showed increasing trend from low B concentrations, 1.0 mM. Therefore, B stress can be claimed as “doubled edge sword” for these lentil species.

Abbreviations

AOS, active oxygen species; APX, ascorbate peroxidase; CAT, catalase; DAB, diamino-benzidine tetrahydrochloride; DMSO, dimethyl sulfoxide DW, dry weight; EDTA, ethylenediamine-N,N,N₀,N₀-tetraacetic acid; FW, fresh weight GPX, guaiacol peroxidase; GSH-P_x, glutathione peroxidase; LOX, lipoxygenase; MDA, malondialdehyde; NBT, nitroblue tetrazolium; PEG, polyethylene glycol; ROS, reactive oxygen species; SOD, superoxide dismutase; H₂O_2, Hydrogen peroxide;