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1.
In preparation for gene transfer experiments we investigated factors that might affect the production of shoots and somatic embryos from the wound callus of cultured sugarbeet leaf discs. A complex interaction was found between the leaf disc plating density, the disc culture medium, the source-shoot culture medium and the frequency of disc transfer to fresh medium. The most productive protocol utilized: source shoots maintained on MS medium containing 0.25 mg 1 -1 BA; multiple leaf discs (ten 4-mm discs/plate) plated onto an enriched modification of MS medium (RV) containing 1.0 mg 1 -1 BA and solidified with 0.3% Gelrite (not permitted to dry during hardening); and transfer of the discs to fresh medium every two weeks during the first month. This standard protocol produced more callus per plate and higher rates of morphogenesis per unit dry weight of callus than did the one-step method of Saunders and Doley. Water availability considerations were found to be critical to obtaining high morphogenic rates. Root induction frequency and quality was superior on shoots transplanted to MS medium containing 1 mg 1 -1 NAA as the sole growth regulator compared to IAA at the same concentration.Abbreviations BA
N 6-benzyladenine
- IAA
indole-3-acetic acid
- NAA
-naphthaleneacetic acid 相似文献
2.
We examined ethylene effects on root regeneration in tomato leaf discs cultured in vitro. Applied ethylene or Ethephon did not stimulate rooting in the leaf discs. In the presence of indoleacetic acid. 5 × 10 -6M, these substances significantly inhibited root formation. Ethylene production (nl C 2H 4· (24 h) -1. flask -1) was positively correlated with increased IAA concentrations at various times during the culture period and, as a consequence, with the rooting response after 168 h. However, separate testing of equimolar concentrations of seven different auxins and auxin-like compounds showed no positive correlation between the rate of ethylene production and subsequent rooting response. Aeration of gas-tight flasks containing leaf discs and absorption of ethylene evolved from the discs by mercuric perchlorate in gas-tight flasks or pre-treatment of leaf discs with AgNO 3 significantly enhanced IAA induced root regeneration. Thus, these studies indicate that ethylene is not a rooting hormone per se. Furthermore, ethylene (whether applied externally or synthesized by the tissue) does not appear to account for the ability of auxin to stimulate rooting. 相似文献
3.
A rapid quantitation of proteoglycan synthesis distribution in intervertebral disc and endplates is described. Tissue blocks of disc (C7-Th1) in the midsagittal plane from ten female beagles were incubated in the presence of 35SO 4 and prepared as histological slides. For comparison, sulphate incorporation rates in the C5–C6 discs were assayed by liquid scintillation. Autoradiographic film exposed against the labelled sections was developed and digitized for image analysis using a 256 grey level flat bed table scanner connected to a microcomputer. The film density versus dpm (disintegrations per minute) calibration was performed using a set of 35SO 4-labelled glycosaminoglycan standards applied on the same film. Since section thickness, dpm calibration of the film density and the specific activity of sulphate in the medium were known, the incorporations per tissue volume could be calculated. The average incorporation rates of the anterior and posterior annulus fibrosus, nucleus pulposus and vertebral endplates were 5.2±0.9, 5.2±0.8, 4.5±0.6 and 4.1±0.8 pmol/mm 3 per h (±SE, n=10), respectively and closely corresponded to those obtained by liquid scintillation. This method offers a convenient and reproducible way to measure the rate of proteoglycan synthesis in large tissue sections but also in thin cartilaginous tissues such as the vertebral endplate. 相似文献
4.
The permeability properties of frog rod photoreceptor outer segment discs were investigated in preparations of purified, dark-adapted, outer segment fragments by the techniques of direct volume measurement and electron microscopy. Outer segment discs were found to swell and contract reversibly in response to changes in the osmotic pressure of the bathing medium in accordance with the Boyle-van't Hoff law. By use of the criterion of reversible osmotic swelling, the disc membrane is impermeable to Na +, K +, Mg +2, Ca +2, Cl -, and (PO 4) -3 ions, whereas it is freely permeable to ammonium acetate. The disc membrane is impermeable to sucrose, although its osmotic behavior towards this substance is different from its behavior towards impermeable ions. Electron microscopy showed that the osmotic effects on the rod outer segment fragments represent changes in the intradiscal volume. Fixation with glutaraldehyde did not abolish the permeability properties of the disc membrane, and fixed membranes were still capable of osmotic volume changes. It is concluded from this study that the frog's rod photoreceptor outer segment discs are free-floating membranous organelles with an inside space separate and distinct from the photoreceptor intracellular space. 相似文献
5.
Exposure of ferredoxin-dependent glutamate synthase (EC 1.4.7.1) mutants of Arabidopsis thaliana to photorespiratory conditions resulted in the accumulation of NH 4+ and the inhibition of photosynthesis. However, upon transfer from 2% O 2, 350 microliters per liter CO 2, to 21% O 2, 350 microliters per liter CO 2, net photosynthesis declined at a slower rate in methionine sulfoximine treated leaf discs relative to controls. The recovery of photosynthesis was also more rapid in MSO-treated leaf discs although ammonia levels were more than threefold higher. Photosynthesis in leaf discs treated with azaserine was inhibited more than controls when transferred to 21% O 2 and recovered less than controls when returned to 2% O 2 although NH 4+ levels were not significantly different. The results obtained are consistent with the view that the rapid inhibition of photosynthesis in the glutamate synthase mutants in photorespiratory conditions is not due to the accumulation of NH 4+ but rather to the depletion of amino donors for glyoxylate and the consequent effects of glyoxylate on the lack of return of carbon to the chloroplast. 相似文献
6.
To test the “Ca 2+ hypothesis of visual excitation”, we measured the total Ca 2+ content of freshly isolated bullforg rod outer segments, and have compared the total Ca 2+ contents of fully dark-adapted discs with discs exposed to small amounts of light. Discs were prepared by hypotonically lysing outer segments under conditions expected to remove Ca 2+ from the cytoplasm but not from the discs. Ca 2+ was assayed by atomic absorption spectrophotometry. We find that both discs and outer segments contain a total of about 0.1–0.2 Ca 2+ per rhodopsin molecule. Thus, each frog disc retains about . If most of this Ca 2+ were free in the aqueous space inside the intact discs, the Ca 2+ activity would be a few mM. Since the light-regulated Na + channels have been reported to be highly sensitive to cytoplasmic Ca 2+, this store of Ca 2+ in the discs is far more than required by the Ca 2+ hypothesis. However, despite several variations in experimental conditions, we did not observe any light-activated release of Ca 2+ from discs in response to stimuli that photoactivated a small fraction of the rhodopsin, as required by the Ca 2+ hypothesis. In the 26 experiments reported here we could have detected a release as small as 20–30% of the Ca 2+ content of the disc. 相似文献
7.
A leaf chamber has been designed which allows the measurement of both CO 2 and water vapor exchange in Spinacia oleracea leaf discs. The center of the disc lies within a cylindrical gas chamber and its margins are enclosed within a cavity through which water or various metabolites can be pumped. In saturating light and normal atmospheres, the leaf discs have a relatively low resistance to H 2O vapor transfer ( rw = 1.87 seconds per centimeter) and can support high rates of photosynthesis for several hours. The abaxial surface of a disc had a higher resistance to water vapor transfer ( rw = 3.22 seconds per centimeter) than the adaxial ( rw = 2.45 seconds per centimeter) despite having a higher stomatal frequency (abaxial, 105/square millimeter; adaxial, 58/square millimeter). In 2% O 2, the discs required an internal concentration of CO 2 of 115 microliters per liter to support one-half of the maximal velocity of apparent photosynthesis (average value, 66 milligrams CO 2 per square decimeter per hour). In 20% O 2, the comparable values are 156 microliters per liter and 56 milligrams CO 2 per square decimeter per hour. In air, apparent photosynthesis saturated at intensities (750 microeinsteins per square meter per second) well below that of daylight but, when the internal CO 2 was raised to 700 to 900 microliters per liter, photosynthesis was not saturated even at daylight intensities (2025 microeinsteins per square meter per second). The distribution of Prussian blue crystals, formed after ferrocyanide feeding, showed that water entered the disc via the vasculature. When 25-minute pulses of orthophosphate were provided in the feeding solution, there were concentration-dependent increases in both rw and rm leading to inhibition of photosynthesis. The orthophosphate-dependent inhibitions were reversible. 相似文献
8.
Leaf discs and detached leaves exposed to l-cysteine emitted a volatile sulfur compound which was proven by gas chromatography to be H 2S. This phenomenon was demonstrated in all nine species tested ( Cucumis sativus, Cucurbita pepo, Nicotiana tabacum, Coleus blumei, Beta vulgaris, Phaseolus vulgaris, Medicago sativa, Hordeum vulgare, and Gossypium hirsutum). The emission of volatile sulfur by cucumber leaves occurred in the dark at a similar rate to that in the light. The emission of leaf discs reached the maximal rate, more than 40 picomoles per minute per square centimeter, 2 to 4 hours after starting exposure to l-cysteine; then it decreased. In the case of detached leaves, the maximum occurred 5 to 10 h after starting exposure. The average emission rate of H 2S during the first 4 hours from leaf discs of cucurbits in response to 10 millimolar l-cysteine, was usually more than 40 picomoles per minute per square centimeter, i.e. 0.24 micromoles per hour per square decimeter. Leaf discs exposed to 1 millimolar l-cysteine emitted only 2% as much as did the discs exposed to 10 millimolar l-cysteine. The emission from leaf discs and from detached leaves lasted for at least 5 and 15 hours, respectively. However, several hours after the maximal emission, injury of the leaves, manifested as chlorosis, was evident. H 2S emission was a specific consequence of exposure to l-cysteine; neither d-cysteine nor l-cystine elicited H 2S emission. Aminooxyacetic acid, an inhibitor of pyridoxal phosphate dependent enzymes, inhibited the emission. In a cell free system from cucumber leaves, H 2S formation and its release occurred in response to l-cysteine. Feeding experiments with [ 35S] l-cysteine showed that most of the sulfur in H 2S was derived from sulfur in the l-cysteine supplied and that the H 2S emitted for 9 hours accounted for 7 to 10% of l-cysteine taken up. 35S-labeled SO 32− and SO 42− were found in the tissue extract in addition to internal soluble S 2−. These findings suggest the existence of a sulfur cycle which converts l-cysteine to SO 42− through cysteine desulfhydration. 相似文献
9.
A new method for growing Aspergllius flavus for experimental studies is presented. The system consists of a humidified vial with a thick septum pierced by a pin on which a glass fiber disc is affixed. The disc contains the test solution and inoculum plus medium. The method has been used to assess the effect of variations in culture conditions on production of aflatoxin B 1 (AFB 1). The AFB 1 level was affected by the amount of medium placed on the disc and type of disc material. The results for different types of glass fiber and quartz discs were compared with AFB 1 produced by fungus grown in liquid medium or on paper discs. When compared to a liquid medium culture there was a 15 to 20-fold increase in AFB 1 for one type of disc. Incubations with less than 14 µl of medium gave satisfactory results. A crude phosphatidylcholine preparation at a concentration of 0.7% of the medium resulted in a 4-fold increase in AFB 1.Abbreviations AFB 1
aflatoxin B 1
- CV
coefficient of variation
- PC
phosphatidylcholine
- SD
suspended disc 相似文献
10.
When leaf discs of Lycopersicon esculentum Mill. cv. Rutgers were floated on solutions containing 4.33 × 10 –6 M gibberellic acid (GA 3), 1.0 ×x 10 –6M boron (B), separately and together, senescence was retarded with respect to controls. Degradation of chlorophyll, total protein, RNA, and DNA was delayed, and decreases in fresh weight and leaf disc diameter checked. The loss of chlorophyll, protein, RNA, DNA, fresh weight, and diameter were 10, 20, 30, 8, 28, and 0 per cent with GA 3 alone; 15, 25, 35, 8, 31, and 0 per cent with B alone; 8, 14, 25, 7, 25, and 0 per cent with GA 3 plus B; contrasted with 50, 40, 50, 9, 42, and 3 per cent for the controls. An analysis of variance was performed on all data except for disc diameter. All sources of variance were significantly or highly significant at the 1 per cent level except for the effect of boron on DNA level, which was significant only at the 2.5 per cent level. Retardation of senescence by GA 3 may be associated with the known ability of GA 3 to stimulate m-RNA and protein synthesis. The effect of boron may be due to an effect on sugar and starch balance, translocation of sugar, or on water balance, but more likely boron plays a role in nucleotide and protein metabolism in plants. Boron may be involved in the synthesis of DNA, a role perhaps mediated by GA 3. 相似文献
11.
Based on results obtained with leaf discs exposed to sulfate, leaves on cucurbit plants ( Cucurbita pepo L. cv Small Sugar Pumpkin and Cucumis sativus cv Chipper) 1 to 2.5 weeks old have a low potential for H 2S emission (less than 10 picomoles per min per cm 2 leaf area) in response to sulfate, whereas discs from most of the leaves on plants 3 to 4 weeks old emit H 2S at a higher rate (50 to 150 picomoles per min per cm 2 leaf area). This difference is determined by the age of the plant, and is independent of the leaves' age or developmental stage. In response to l-cysteine, however, discs from leaves on cucurbit plants 1 to 2.5 weeks old emit H 2S at higher rates (15 to 50 picomoles per min per cm 2 leaf area) than in response to sulfate. Furthermore, the potential for H 2S emission in response to l-cysteine decreases with increasing age of the individual leaf. Thus, most of the potential for H 2S emission in response to l-cysteine is developed during germination and the early growth of cucurbit plants, but most of the potential for H 2S emission in response to sulfate arises later in the development of the plants. 相似文献
12.
Betacyanin leakage from beet root discs was found to increase with decreasing pH of the incubation medium. Although 10 millimolar Ca 2+ reduced pigment leakage at pH 3.5, it was ineffective at pH 2.3. Leakage was also stimulated by 100 micrograms per milliliter (2-chloroethyl)-phosphonic acid (pH 3.1), but when the solution was neutralized, this leakage was eliminated. Bubbling C 2H 4 through a neutral medium containing beet discs had no effect on pigment leakage; it appears that the effect of Ethephon solutions on this process is a function of their low pH. 相似文献
13.
Lethal and sublethal effects of spirotetramat, spiromesifen and spirodiclofen were assessed on Tetranychus urticae Koch. Leaf disc bioassay was used in all experiments. In this study, toxicity of these compounds was tested on T. urticae eggs and adults. Ovicidal activity was observed in all of the compounds tested, but only spirodiclofen was considerably effective against adult mites. Up to 24?h-old adult females were placed on leaf discs treated with sublethal concentrations (LC 10 or LC 25). Twenty-four hours after exposure to treated discs, 20 females showing no visible symptoms of poisoning were transferred to untreated leaf discs. The leaf discs were changed daily for up to five days. The number of eggs laid during this period was recorded. The survival rate, total number of laid eggs per female and egg hatching rate were calculated. All above-mentioned parameters were slightly lower in treated females compared with controls. 相似文献
14.
Effects of the gibberellins A 4+7(GA 4+7) and A 3(GA 3), benzyladenine (BA) and forchlorfenuron (CPPU) on deposition of the cuticular membrane (CM) in developing tomato ( Lycopersicon esculentum L.) fruit were investigated. Growth regulators were applied when fruit development within trusses ranged from the flower
to the mature stage. Developmental stage of fruit at the time of application was indexed by fruit diameter. Fruit were harvested
at maturity, the CM isolated enzymatically on an individual fruit basis and mass of CM per unit fruit surface area calculated.
In mature fruit, mass of CM per fruit increased with fruit size, but mass of CM per unit surface area was independent of fruit
size, position within a truss and position of the truss on the plant. GA 4+7 and GA 3 increased CM mass per unit fruit surface area at concentrations up to 300 mg l −1. Young fruit (5–10 mm diam. at time of application) was most responsive. Responsiveness decreased as fruit development at
application progressed towards maturity. There was no consistent effect of GA 4+7 or GA 3 on fruit mass. BA (up to 100 mg l −1) or CPPU (up to 3 mg l −1) had no significant effect on CM mass per unit surface area regardless of developmental stage. Higher concentrations of BA
or CPPU decreased CM mass per unit surface area. There was no effect of BA or CPPU on fruit mass. Potential mechanisms and
benefits of a gibberellin induced increase in CM deposition are discussed. 相似文献
15.
To investigate the effects of glucohexaose (P6) on cucumber, leaf CO 2 assimilation, chlorophyll fluorescence parameters, chlorophyll content, and carbohydrate metabolism were examined in cucumber plants. The net photosynthetic rate ( P n ) of cucumber leaves was enhanced after being treated with 10 μg mL ?1 P6. The increase was correlated with increases in transpiration rate ( E) and stomatal conductance ( G s), whereas the intercellular CO 2 concentration ( C i) was not different from the control plants. Chlorophyll content, absorption of light energy per unit area (ABS/CS), capture of light energy per unit area (TR o/CS), quantum yield of electron transport per unit area (ET o/CS), maximum photochemical efficiency of PSII ( φP o), quantum yield of photosynthetic institution electron transfer ( φE o), probability of other electron acceptors that captured exciton-transferred electrons to the electronic chain which exceeds QA ( ψ o), number of reaction centers per unit leaf area (RC/CS o), and the performance index on absorption basis (PI ABS) were improved, but heat dissipation per unit area (DI o/CS) and maximum quantum yield of non-chemical quenching ( φD o) were reduced. In addition, increases in sucrose, soluble sugars, and starch contents were observed in P6-treated plants. However, H 2O 2 scavenger (DMTU) or NADPH oxidase inhibitor (DPI) pretreatment significantly abolished the effect of P6 on photosynthesis. The results demonstrated that ROS played a critical role in P6-induced photosynthesis. The increase in chlorophyll content together with efficient light absorption, transmission, and conversion in P6-treated plants is important for increasing photosynthesis. 相似文献
16.
Enzymatic activities of glutamate dehydrogenase (GDH) and glutamine synthetase (GS) participating in the nitrogen metabolism and related ammonium absorption were assayed after the microalga Chlorella vulgaris Beij. was jointly immobilized with the microalgae‐growth‐promoting bacterium Azospirillum brasilense. At initial concentrations of 3, 6, and 10 mg · L ?1 NH 4+, joint immobilization enhances growth of C. vulgaris but does not affect ammonium absorption capacity of the microalga. However, at 8 mg · L ?1 NH 4+, joint immobilization enhanced ammonium absorption by the microalga without affecting the growth of the microalgal population. Correlations between absorption of ammonium per cell and per culture showed direct (negative and positive) linear correlations between these parameters and microalga populations at 3, 6, and 10 mg · L ?1 NH 4+, but not at 8 mg · L ?1 NH 4+, where the highest absorption of ammonium occurred. In all cultures, immobilized and jointly immobilized, having the four initial ammonium concentrations, enzymatic activities of Chlorella are affected by A. brasilense. Regardless of the initial concentration of ammonium, GS activity in C. vulgaris was always higher when jointly immobilized and determined on a per‐cell basis. When jointly immobilized, only at an initial concentration of 8 mg · L ?1 NH 4+ was GDH activity per cell higher. 相似文献
17.
There has been renewed interest in the combined use of high-rate algal ponds (HRAP) for wastewater treatment and biofuel production. Successful wastewater treatment requires year-round efficient nutrient removal while high microalgal biomass yields are required to make biofuel production cost-effective. This paper investigates the year-round performance of microalgae in a 5-ha demonstration HRAP system treating primary settled wastewater in Christchurch, New Zealand. Microalgal performance was measured in terms of biomass production, nutrient removal efficiency, light absorption and photosynthetic potential on seasonal timescales. Retention time-corrected microalgal biomass (chlorophyll a) varied seasonally, being lowest in autumn and winter (287 and 364 mg m ?3day ?1, respectively) and highest in summer (703 mg m ?3day ?1), while the conversion efficiency of light to biomass was greatest in winter (0.39 mg Chl- a per μmol) and lowest in early summer (0.08 mg Chl- a per μmol). The percentage of ammonium (NH 4–N) removed was highest in spring (79 %) and summer (77 %) and lowest in autumn (47 %) and winter (53 %), while the efficiency of NH 4–N removal per unit biomass was highest in autumn and summer and lowest in winter and spring. Chlorophyll-specific light absorption per unit biomass decreased as total chlorophyll increased, partially due to the package effect, particularly in summer. The proportional increase in the maximum electron transport rate from winter to summer was significantly lower than the proportional increase in the mean light intensity of the water column. We concluded that microalgal growth and nutrient assimilation was constrained in spring and summer and carbon limitation may be the likely cause. 相似文献
18.
PurposeTo assess the prevalence of glaucoma in patients with high myopia defined as myopic refractive error of >-8 diopters or axial length ≥26.5 mm. MethodsThe hospital-based observational study included 172 patients (336 eyes) with a mean age of 61.9±12.3 years and mean axial length of 30.1±2.3 mm (range: 24.7–39.1mm). Glaucomatous-type optic discs were defined by glaucomatous optic disc appearance. Glaucoma was defined by glaucomatous optic disc appearance and glaucomatous Goldmann visual field defects not corresponding with myopic macular changes. ResultsLarger disc area (mean: 3.18±1.94 mm 2) was associated with longer axial length ( P<0.001; standardized correlation coefficient: 0.45). Glaucoma was detected in 94 (28%; 95% Confidence intervals: 23%, 33%) eyes. In multivariate analysis, glaucoma prevalence was 3.2 times higher ( P<0.001) in megalodiscs (>3.79 mm 2) than in normal-sized discs or small discs (<1.51 mm 2) after adjusting for older age. Axial length was not significantly ( P = 0.38) associated with glaucoma prevalence in that model. Glaucoma prevalence increased by a factor of 1.39 for each increase in optic disc area by one mm 2. Again, axial length was not significantly ( P = 0.38) associated with glaucoma prevalence when added to this multivariate model. ConclusionWithin highly myopic individuals, glaucoma prevalence increased with larger optic disc size beyond a disc area of 3.8 mm 2. Highly myopic megalodiscs as compared to normal sized discs or small discs had a 3.2 times higher risk for glaucomatous optic nerve neuropathy. The increased glaucoma prevalence in axial high myopia was primarily associated with axial myopia associated disc enlargement and not with axial elongation itself. 相似文献
19.
The addition of glyoxylate to tobacco ( Nicotiana tabacum) leaf discs inhibited glycolate synthesis and photorespiration and increased net photosynthetic 14CO 2 fixation. This inhibition of photorespiration was investigated further by studying the effect of glyoxylate on the stimulation of photosynthesis that occurs when the atmospheric O 2 level was decreased from 21 to 3% (the Warburg effect). The Warburg effect is usually ascribed to the increased glycolate synthesis and metabolism that occurs at higher O 2 concentrations. Photosynthesis in control discs increased from 59.1 to 94.7 micromoles of CO 2 per gram fresh weight per hour (a 60% increase) when the O 2 level was lowered from 21 to 3%, while the rate for discs floated on 15 millimolar glyoxylate increased only from 82.0 to 99.7 micromoles of CO 2 per gram fresh weight per hour (a 22% increase). The decrease in the O 2 sensitivity of photosynthesis in the presence of glyoxylate was explained by changes in the rate of glycolate synthesis under the same conditions. The rate of metabolism of the added glyoxylate by tobacco leaf discs was about 1.35 micromoles per gram fresh weight per hour and was not dependent on the O2 concentration in the atmosphere. This rate of metabolism is about 10% the amount of stimulation in the rate of CO2 fixation caused by the glyoxylate treatment on a molar carbon basis. Glyoxylate (10 millimolar) had no effect on the carboxylase/oxygenase activity of isolated ribulose diphosphate carboxylase. Although the biochemical mechanism by which glyoxylate inhibits glycolate synthesis and photorespiration and thereby decreases the Warburg effect is still uncertain, these results show that cellular metabolites can regulate the extent of the Warburg effect. 相似文献
20.
Summary The absorption of N from foliar applications of various N sources by pine seedlings was studied under greenhouse conditions.
Needles dipped into solutions of 4,000 ppm N from Ca(NO 3) 2 were burned slightly at the tips at two weeks. Although higher concentrations of (NH 2) 2CO and (NH 4) 2SO 4 could be used without plant damage, a uniform concentration of 3,000 ppm was used in all comparative tests of sources.
The level of tissue N, brought about by soil fertilization 6 weeks previously, did not significantly influence absorption
of foliarly applied N 15. Soil moisture maintained at near 100, 60 to 70, and 25 to 35 per cent of water-holding capacity of the Leon fs did not significantly
affect the absorption of tagged N.
Greater quantities of N 15 were absorbed as urea than as Ca(NO 3) 2 or (NH 4) 2SO 4. The use of a spreader-sticker increased the N 15 uptake, regardless of the N compound used. However, the magnitude of the increased absorption associated with use as a sticker
varied from 490 per cent with (NH 4) 2SO 4 to 260 per cent with urea. It was calculated that approximately 71, 45, and 39 per cent of foliar applied N was absorbed
into needles within 24 hours from urea, Ca(NO 3) 2, and (NH 4) 2SO 4, respectively.
Journal Paper No 3588 of the Florida Agricultural Experiment Station, Gainesville, Florida. 相似文献
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