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1.
Summary The effect of increasing rates of nitrogen (N) and sulphur (S) as fertilizers on the yield, leaf area and N, P, S, Ca, Mg,
NO3
− and SO4
= content in leaves of bean (Phaseolus vulgaris, L.) were studied in a hydroponic culture experiment under greenhouse conditions.
Bean plants responded significantly to all treatments with differents N/S ratios. When plants grew with high N/S ratios, the
leaf content of N, Ca and NO3
− increased while the content of K, P and SO4
= decreased. However, optimal yield and leaf area were not obtained. Optimal leaf and fruit dry matter was obtained at N/S
ratio value of 1.41. When lower N/S rates were used, optimal leaf and fruit dry matter was only observed when the leaf N/S
ratio was between 15 and 16. At high sulphate levels in the nutrient solution there is no interaction with nitrate which is
easily observed, resulting in an increase in yield.
An interaction between nitrate and sulphate in the nutrient solution was found at a N/S ratio of 0.81 which produced in leaves
a synergic effect between P-K, an antagonistic effect between N-P and N-K and a lower yield.
This research was supported by Fundacion ‘Ramon Areces’. 相似文献
2.
Patrick H. Brown Steven A. Weinbaum Geno A. Picchioni 《Trees - Structure and Function》1995,9(3):158-164
The influence of alternate bearing on nutrient utilization and total tree nutrient content was investigated in mature pistachio
(Pistacia vera L. cv Kerman trees). Removal of N, P and Zn in fruit and abscised leaves of cropping (‘on’) trees averaged 5, 6, and 2 times,
respectively, the removal in abscised leaflets of the non-fruiting, ‘off’ year trees. One hundred and thirty-five kg N, 131
kg K, 86 kg Ca, 39 kg Mg and 18 kg P per hectare were removed in fruits and abscised leaves in ‘on’ year trees. Tree nutrient
contents and, presumably, the size of nutrient storage pools in dormant trees varied between ‘on’ and ‘off’ years. There was
22% and 14% more N and P, respectively, in dormant trees following ‘off’ than ‘on’ years. The greater N and P accumulation
in ‘off’ year trees is depleted in support of the large fruit demand for N and P during ‘on’ years. In contrast to N and P,
there was greater K and Ca accumulation in perennial tree parts during ‘on’ years than during ‘off’ years. The greater K accumulation
in perennial tree parts and approximately 30% greater removal of K in annual organs during ‘on’ than ‘off’ years suggests
that K uptake could be 4 times higher in ‘on’ year trees than in (non-cropping), ‘off’ year trees. 相似文献
3.
A greenhouse study was conducted to determine the effect, of certain nutrient elements, on the maturing peanut. Peanut fruits
were grown in fruiting zones, which contained a complete nutrient medium, for 15 days. Individual plants were then cultured
to maturity whilst allowing the fruit to develop in a nutrient medium which contained the complete nutrient (N, P, K, Ca,
Mg and B) from which one element had been excluded.
Except in the ‘minus B’ treatment, the basal seed weighed more than 500 mg. In the head seed the “minus Ca” treatment produced
the lowest number of seeds which weighed 500 mg or more and P, K and B deficiencies produced not quite such low numbers of
seeds above 500 mg. When basal and head seeds were grouped into 3 grades of fresh weights, those from Ca and K deficiencies
produced smaller dry weights in seeds harvested on the 80th day. Seeds from a Ca deficient medium had a smaller lipid content
and an increased sugar content. The starch content of the seed was decreased by K deficiency. 相似文献
4.
Chao L Bofu P Weiqian C Yun L Hao H Liang C Xiaoqing L Xiao W Fashui H 《Biological trace element research》2008,122(3):266-275
The main aim of the study was to determine the role of cerium in the amelioration of calcium-deficiency effects in spinach
plants. Spinach plants were cultivated in Hoagland’s solution. They were subjected to calcium-deficiency and to cerium chloride
administered in the calcium-present Hoagland’s media and calcium-deficient Hoagland’s media. Within 3weeks, young leaves developed
distinct calcium-deficient symptoms, and plant growth significantly inhibited to calcium deprivation as would be expected;
cerium-treated groups grown in the same conditions did not develop calcium-deficient symptoms; fresh weight, dry weight and
chlorophyll content of spinach plants were increased by 35.9, 45 and 64.05% compared to those of plants cultivated in calcium-deficient
media. In addition, calcium deprivation in spinach plants caused the reduction of photosynthetic rate, oxygen evolution rate
and ribulose-1,5-bisphosphate carboxylase/oxygenase activity. The reduction of activities of nitrate reductase, glutamate
dehydrogenase, glutamate synthase and glutamic-pyruvic transaminase was observed under calcium-deficient media. However, cerium
treatment under calcium-deficient media could significantly improve photosynthesis and nitrogen metabolism of spinach plants.
This is viewed as evidence that cerium added to calcium-deficient media in the spinach plants could substitute for calcium
and improve spinach growth. 相似文献
5.
Effects of exogenous B supply on growth, B accumulation and distribution of two navel orange cultivars 总被引:3,自引:0,他引:3
Ou Sheng Shang W. Song Yun J. Chen Shu A. Peng Xiu X. Deng 《Trees - Structure and Function》2009,23(1):59-68
To investigate the effects of boron (B) on growth, B concentration and distribution of two navel orange cultivars, ‘Newhall’
(Citrus sinensis Osbeck) and ‘Skagg’s Bonanza’ (Citrus sinensis Osbeck) grafted on the rootstock trifoliate orange [Poncirus trifoliata (L.) Raf.], B at five levels was exogenously supplied to 1-year-old grafted plants of both cultivars under greenhouse conditions.
Plants were grown in sand:perlite (1:1, v/v) medium and were irrigated every 2 days with half-strength Hoagland’s No. 2 nutrient
solutions containing different B, 0.01, 0.05, 0.10, 0.25 and 2.50 mg l−1 (0.25 and 2.50 mg l−1 were considered as control and excess B treatment, respectively, and the other three B levels were considered as low B treatments).
After treatments for 183 days, leaves (from basal, middle, upper parts of the shoots), stem of scion, stem of rootstock and
root were separately sampled. Our results showed that plant growth (plant height, root volume and dry weights of various parts)
was inhibited in response to low or excess B supplies in both cultivars. It was found that B concentrations in the upper leaves
of both cultivars were substantially higher than those in the basal leaves when low concentrations (≤0.05 mg l−1) of exogenous B were applied, suggesting that B was preferentially translocated to the upper-younger leaves to support their
growth. Analysis of B distribution in different parts indicated that translocation of B from the root to the scion’s shoots
(stems and leaves of scion) may be restricted upon exposure to low B conditions. When B was inadequately supplied, growth
of ‘Skagg’s Bonanza’ was better than ‘Newhall’, implying that the former cultivar was more tolerant to low B status, which
may be due to the higher efficiency of B translocation from the root to the scion’s shoots. However, when the plants were
treated with excess B (2.50 mg l−1), both cultivars showed a similar degree of B toxicity. The probability of scion–rootstock interactions in relation to the
differential responses of growth and different efficiency of B translocation involved in the two orange cultivars following
the long-term low B stress were discussed. 相似文献
6.
Summary
Bromus inermis Leyss. was grown in a 2×2×2 factorial design using different levels of mycorrhizal inoculation (inoculated and noninoculated),
soil water stress (Ψ1 or −0.8 MPa) and potassium (K) fertilization (0 or 150 ppm) as factors. Soil water stress and mycorrhizal inoculation significantly
reduced plant top dry weight during the 18 week study. Chlamydospore production by the mycorrhizal symbiontGlomus fasciculatum (Thaxter sensu. Gerd.) Gerd. and Trappe was significantly reduced by soil water stress of −0.8 MPa. Potassium (K) fertilization
did not significantly influence plant top growth or mycorrhizal colonization. However, foliar Ca and Mg were significantly
lower in plants fertilized with K. Foliar Ca and Mg concentrations of P, K, N, Mn, Zn and Cu were significantly greater in
drought stressed plants whereas Ca and Mg concentrations were significantly greater in well-watered plants. 相似文献
7.
Tesfay Teklay 《Plant and Soil》2004,267(1-2):297-307
Foliar inputs from indigenous agroforestry trees and shrubs could provide sufficient nutrients and organic matter to sustain
crop growth. However, concentrations of foliar nutrients and organic constituents show considerable seasonal, inter- and/or
intra-species variations. To determine this variability, green and senesced leaves were sampled during dry and wet seasons
from Cordia africana, Albizia gummifera and Milletia ferruginea trees at Wondo Genet, southern Ethiopia. Cordia is a deciduous, non-leguminous tree, while Albizia and Milletia are semi-deciduous and leguminous trees. Leaves were analyzed for concentrations of ash, N, P, K, cellulose, lignin, soluble
polyphenols, and condensed tannins. Results from statistical analyses showed significant seasonal variations (P < 0.001) in concentrations of all leaf constituents, except for P and cellulose. Foliar concentrations of ash, N, soluble
polyphenols, and condensed tannins were higher during the wet season while those of K and lignin were higher during the dry
season. Green leaves had significantly higher (p < 0.001) N and P concentrations than senesced leaves, while senesced leaves had higher concentrations of K, cellulose, soluble
polyphenols, and condensed tannins. The ‘ Relative Percentage Changes’ in concentration of N and P in senesced leaves, i.e.,
their enrichment or depletion with such nutrients relative to those in green leaves, were significantly higher (P < 0.001) for Cordia than Albizia and Milletia. On the other hand, there was no consistent pattern in the enrichment or depletion of senesced leaves with organic constituents,
but these leaves were in most cases more enriched with organic constituents than green leaves. Over all, the percentage depletion
or enrichment ranged from about 8% to 38% for N; 24% to 63% for P; −141% to 48% for K; −44% to 15% for cellulose; −44% to
51% for lignin; −203% to −61% for soluble polyphenols; and −290% to 11% for condensed tannins. It was concluded that variations
in species and life-form (legume versus non-legume), season, and developmental stage of leaves could affect the quality of
organic material from agroforestry species, which has important implications for management of organic residues in tropical
agricultural systems. 相似文献
8.
Decomposition of emergent macrophytes in a Wisconsin marsh 总被引:6,自引:3,他引:3
Piboon Puriveth 《Hydrobiologia》1980,72(3):231-242
Loss of both dry weight and nutrients during decomposition was measured using litter bags, both in a natural marsh and in controlled experiments. At 348 days dry weight remains of Typha latifolia, Sparganium eurycarpum, Scirpus fluviatilis shoot litter in the marsh were 47.5, 26.9, 51.4% respectively, and for the rootrhizome litter were 59.1, 42.1, 27.8% (Scirpus > Sparganium > Typha). Under controlled conditions both temperature and type of water produced significant effect on dry weight loss of Typha leaves. Sterilization and antibiotics effectively inhibited the growth and activities of decomposers. Initial weight, N, P, Ca, and Mg losses resulted chiefly from leaching. These elements accumulated in spring and summer; N exhibited the highest accumulation. In the laboratory, N accumulation occurred within 15 days, as a result of microorganisms inhabiting the litter. Increase in P, Ca, Mg in later stages of decomposition were attributed to microorganisms, epiphytes, and precipitation from solution. High C : N ratios and relatively low P, Ca, Mg in original standing crop may be the cause of low herbivore consumption, whereas the relative increases in N, P, Ca, Mg in decomposed litter provide a more nutrient-rich substrate for detritivores. Much of the nutrient uptake in the annual cycle is via microbial and detritivore growth rather than by macrophyte producers. 相似文献
9.
Concentrations of N, P and K were measured in floodwater and in floating rice cultivars growing at up to 2m water depths in
the central flood plain of Thailand. Concentrations of N, P and K in floodwater were often higher than those reported for
oligotrophic lakes, nevertheless the floodwater contained 4–45 times less K and 15–90 times less N than concentrations reported
in most soil solutions. P concentrations were similar in the floodwater and in most soil solutions.
Concentrations of nutrients in leaves indicated there may be deficiencies of P at two sites and a deficiency of N at one of
two sites. Data are discussed in terms of reduced nutrient uptake in rice fields at low O2 concentrations which have recently been measured in these areas. 相似文献
10.
Qualea parviflora Mart. (Vochysiaceae) is a deciduous tree, commonly observed in campo sujo, cerrado sensu stricto and cerradão vegetation types in Brazilian cerrado (savannas). In this study we investigated herbivory, nutritional, and water status effects on leaf sclerophylly of Q. parviflora. Twenty fully expanded leaves were taken from 10 plants in each vegetation type four times a year. Mean leaf concentration of N, P, K, Ca, C, Al, Si, and percentage of total phenols, herbivory and tannins were measured on a plant basis. Leaf specific mass (LSM) (g m?2), a sclerophylly index, and pre-dawn leaf water potential (MPa) were also recorded. Soil samples below each tree were collected to quantify N–NO3, N–NH4, P, K, Mn, soil moisture, organic matter, Si, and Al. Qualea parviflora showed a LSM from 69 to 202 g m?2 and leaves were younger and less sclerophyllous in November (beginning of rainy season). Q. parviflora inhabiting the cerradão had leaves with higher concentration of nutrients and lower sclerophylly while trees in campo sujo and cerrado sensu stricto did not show significant differences in leaf sclerophylly. The concentrations of N, P, K and tannins had an inverse relationship with leaf age. Concentration of phenols, Al, C, Ca, Si, C/N and Ca/K increased with leaf age. The concentrations of P and Ca/K ratio in leaves explained 60% of variation observed in leaf sclerophylly. We did not find any significant relationship between the level of sclerophylly and water potential or herbivory. Our results corroborate the hypothesis that predicts lower concentrations of essential macronutrients would be the main factors influencing higher sclerophylly in leaves of Q. parviflora plants in Cerrado. 相似文献
11.
A. L. García L. Marcelis F. Garcia-Sanchez N. Nicolas V. Martínez 《Biologia Plantarum》2007,51(4):707-712
The responses of water relations, stomatal conductance (gs) and growth parameters of tomato (Lycopersicon esculentum Mill. cv. Royesta) plants to nitrogen fertilisation and drought were studied. The plants were subjected to a long-term, moderate
and progressive water stress by adding 80 % of the water evapotranspirated by the plant the preceding day. Well-watered plants
received 100 % of the water evapotranspirated. Two weeks before starting the drought period, the plants were fertilised with
Hoagland’s solution with 14, 60 and 110 mM NO3
− (N14, N60 and N110, respectively). Plants of the N110 treatment had the highest leaf area. However, gs was higher for N60 plants and lower for N110 plants. At the end of the drought period, N60 plants showed the lowest values
of water potential (Ψw) and osmotic potential (Ψs), and the highest values of pressure potential (Ψp). N60 plants showed the highest Ψs at maximum Ψp and the highest bulk modulus of elasticity. 相似文献
12.
The effect of Ca on Cu toxicity in runner bean plants (Phaseolus coccineus L. cv. Piěkny Jaś) grown hydroponically in nutrient solution was studied. The toxic effect of excess Cu on plants depends on their
age and Ca content in the medium. Copper applied in excess to the plants at the early phase of leaf development strongly limits
the uptake of Ca ions from the nutrient solution, particularly their translocation to leaves. Increased Ca content limits
the inhibitory effect of Cu on leaf growth and decreases the content of chloroplast pigments to the level approximate to that
of control. At this growth stage the effect of excess Cu is at least partially connected with limited Ca transport to leaves.
At the intermediate leaf phase Cu-treated plants react slightly to changed Ca content.
At the end of the primary leaf development increased Ca concentration in the medium intensifies senescence processes induced
by excess Cu. The changes are partially connected with intensified water deficit. Increased Ca content in the nutrient solution
limits Cu accumulation in the individual organs of Cu-treated plants. However, Cu accumulation in leaves is not decreased
at a high level of Ca. Copper generally decreases Ca content in the youngest plants, whereas in the oldest ones only in the
case of a low level of Ca in the nutrient solution. 相似文献
13.
Many soybean [Glycine max (L.) Merr.] genotypes that are grown in solution cultures are highly sensitive to the combination of both salinity and inorganic
phosphate (Pi) in the substrate. This effect has been observed on numerous occasions on plants grown in a saline medium that
contained a substantial amount of Ca (i.e., CaCl2/NaCl=0.5 on a molar basis). Because Ca is important in regulating ion transport and membrane permeability, solution culture
experiments were designed to examine the effects of various concentrations of Pi and ratios of CaCl2/NaCl (0 to 0.5 on a molar basis) at a constant osmotic potential (−0.34 MPa) on this adverse interaction. Four soybean cultivars
(‘Lee’, ‘Lee 74’ ‘Clark’ and ‘Clark 63’) were tested.
No adverse salinity x Pi interaction was found on Lee at any ratio and leaf P and Cl were maintained below 300 and 200 mmol
kg−1 dry wt, respectively. Clark, Clark 63 and Lee 74 soybean plants, on the other hand, were severely injured by solution salinity
(−0.34 MPa osmotic potential) when substrate Pi was ≥0.12 mM. Reduced substrate Ca did not intensify the salinity x Pi interaction. On the contrary, the onset of injury was hastened
and more severe with increased CaCl2/NaCl ratios in isotonic solutions. Shoot and root growth rates decreased as injury increased. Leaf P concentrations from
these cultivars grown in saline solutions with 0.12 mM Pi were excessive (>600 mmol kg−1 dry wt) compared with concentrations commonly found in soybean leaf tissue yet they were independent of the severity of injury.
Since leaf Cl increased wiht increased CaCl2/NaCl ratio, we suspect that the severity of foliar injury was related to the combined effects of excessive P and Cl within
the tissue. Lee 74, the only injured cultivar examined that excluded Cl from its leaves, was less sensitive than either Clark
cultivar and its injury was characteristically different. Other ion interactions were reported that may have played a role
in injury susceptibility. 相似文献
14.
Ze Yuguan Zhou Min Luo Luyang Ji Zhe Liu Chao Yin Sitao Duan Yanmei Li Na Hong Fashui 《Biological trace element research》2009,131(2):154-164
The mechanism of the fact that cerium improves the photosynthesis of plants under magnesium deficiency is poorly understood.
The main aim of the study was to determine the role of cerium in the amelioration of magnesium deficiency effects in CO2 assimilation of spinach. Spinach plants were cultivated in Hoagland’s solution. They were subjected to magnesium deficiency
and to cerium chloride administered in the magnesium-present Hoagland’s media and magnesium-deficient Hoagland’s media. The
results showed that the chlorophyll synthesis and oxygen evolution was destroyed, and the activities of Rubisco carboxylasae
and Rubisco activase and the expression of Rubisco large subunit (rbcL), Rubisco small subunit (rbcS), and Rubisco activase subunit (rca) were significantly inhibited, then plant growth was inhibited by magnesium deficiency. However, cerium promotes the chlorophyll
synthesis, the activities of two key enzymes in CO2 assimilation, and the expression of rbcL, rbcS, and rca, thus leading to the enhancement of spinach growth under magnesium-deficient conditions. 相似文献
15.
Legumes as ground cover are regularly planted to increase nitrogen economy of crops and to improve soil. In the present study
various clover species were evaluated as vegetative ground cover in nursery field production of micropropagated red birch
(Betula pubescensEhrh. f. rubraUlvinen f. nova) in two 2-year experiments. The clover species and cultivars, Trifolium pratenseL. ‘Bjursele’, T. repens L. ‘Jogeva’, T. repens L. ‘Sonja’, T. hybridum L. ‘Frida’, T. incarnatum L. ‘Opolska’, T. resupinatum L. and T. subterraneum L. were compared to grass sod Festuca rubra L. ‘Ensylva’ and to a coverless ground (control). The last one was kept weed free by hand hoeing. Birch (leaves, stems, branches
and roots) and soil nutrient concentrations (N, P, K, Ca, Mg and Fe) were analysed and nutrient ratios in birch determined.
The annual clovers, T. incarnatumL., T. resupinatumL. and T. subterraneumL., provided about the same nutrient status in birch as did the control. Perennial clovers and grass were strong competitors
with trees. High levels of P and Mg in birch leaves relative to N concentration were typical for poorly growing seedlings.
Neither annual nor perennial clovers did generally improve soil nutrient status.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
The seasonal dynamics of uptake, partitioning and redistributionof dry matter, N, P, K, S, Ca, Mg, Na, Cl, Fe, Zn, Mn and Cuby the cormaceous plant Ixia flexuosa were studied in pot cultureat Perth, Western Australia. Dry matter and P, N, K, Zn andCu were redistributed from the mother corm with about 90 percent net efficiency: there was no net redistribution of Ca,Na, Fe or Mn. The efficiency of redistribution from the leafyshoot to fruits and the new season's corm was 80 per cent forN and P, 2449 per cent for K, Cu and Zn, and 015per cent for Na, Fe, Ca, Mn, Cl, Mg, S and dry matter. Redistributionfrom the mother corm and vegetative organs could have suppliedthe replacement corm, cormlets and fruits with 3253 percent of their S, K, P, N, Cu and Zn, and 1125 per centof their Ca, Cl, Mn, Mg and dry matter. The mature replacementcorm had over 60 per cent of the plant's N and P, 2550per cent of its dry matter, Zn, Cu, Mg, K and Cl, but less than20 per cent of its Ca, Na, Fe and Mn. Each plant produced anaverage of 12 cormlets; these had 35 per cent of the dry matterand 2347 per cent of the amount of a particular nutrientin the new season's corms. Fruits had less than 16 per centof the dry matter and each mineral in the mature plant. Ratesof mineral intake by Ixia were much lower than reported forcrop plants, and may be related to the long growing season ofthe species. Ixia polystachya L., corm, nutrition, mineral nutrients, nutrient redistribution 相似文献
17.
The effects of placing small amounts of phosphate fertilizer close to the seed on growth and nutrient concentrations of lettuce 总被引:2,自引:0,他引:2
P. A. Costigan 《Plant and Soil》1984,79(2):191-201
Summary Two glasshouse experiments are described in which the effects of applying starter phosphate fertilizer, 1 cm beneath the seeds, on early growth and nutrient concentrations of lettuce (Lactuca sativa L. cv. Avondefiance) in well fertilized soil were determined. In Experiment 1 various rates of starter P in the form of NH4H2PO4 were applied to soil containing a range of rates of incorporated triple superphosphate. Although there was little response of lettuce dry weight to the incorporated triple superphosphate there was a large response (about 65% increase after 36 days) to the starter. N and P concentrations within the plants were increased by the starter treatments whereas K concentration was reduced. The per cent P in the plants at 36 days from sowing could account for 60% of the variation in plant dry weight. In Experiment 2 the starter P was added as either the Ca, Na or K salt, with or without added (NH4)2SO4. Adding the starter P without ammonum increased the P concentration of the plants by an average of 12% and the dry weight by an average of 39% at 30 days from sowing. The addition of ammonium ions increased plant concentrations of P, Mg and N but decreased plant K concentration. The effect of the ammonium ions on growth depended on the form of phosphate supplied as the starter. This variation in effect of ammonium ions was attributed to the effects of other starter ions on the relative concentration of ammonium in the soil solution. 相似文献
18.
Atmospheric changes could strongly influence how terrestrial ecosystems function by altering nutrient cycling. We examined
how the dynamics of nutrient release from leaf litter responded to two important atmospheric changes: rising atmospheric CO2 and tropospheric O3. We evaluated the independent and combined effects of these gases on foliar litter nutrient dynamics in aspen (Populus tremuloides Michx) and birch (Betula papyrifera Marsh)/aspen communities at the Aspen FACE Project in Rhinelander, WI. Naturally senesced leaf litter was incubated in litter
bags in the field for 735 days. Decomposing litter was sampled six times during incubation and was analyzed for carbon, and
both macro (N, P, K, S, Ca, and Mg) and micro (Mn, B, Zn and Cu) nutrient concentrations. Elevated CO2 significantly decreased the initial litter concentrations of N (−10.7%) and B (−14.4%), and increased the concentrations
of K (+23.7%) and P (+19.7%), with no change in the other elements. Elevated O3 significantly decreased the initial litter concentrations of P (−11.2%), S (−8.1%), Ca (−12.1%), and Zn (−19.5%), with no
change in the other elements. Pairing concentration data with litterfall data, we estimated that elevated CO2 significantly increased the fluxes to soil of all nutrients: N (+12.5%), P (+61.0%), K (+67.1%), S (+28.0%), and Mg (+40.7%),
Ca (+44.0%), Cu (+38.9%), Mn (+62.8%), and Zn (+33.1%). Elevated O3 had the opposite effect: N (−22.4%), P (−25.4%), K (−27.2%), S (−23.6%), Ca (−27.6%), Mg (−21.7%), B (−16.2%), Cu (−20.8%),
and Zn (−31.6%). The relative release rates of the nine elements during the incubation was: K ≥ P ≥ mass ≥ Mg ≥ B ≥ Ca ≥ S ≥ N ≥ Mn ≥ Cu ≥ Zn.
Atmospheric changes had little effect on nutrient release rates, except for decreasing Ca and B release under elevated CO2 and decreasing N and Ca release under elevated O3. We conclude that elevated CO2 and elevated O3 will alter nutrient cycling more through effects on litter production, rather than litter nutrient concentrations or release
rates. 相似文献
19.
J. Čatský D. K. Velichkov Jana Pospísilová Jarmila Solárová Ingrid Tichá 《Biologia Plantarum》1987,29(5):355-364
The carbon balances of whole, 21-d old French bean plants (Phaseolus vulgaris L.) grown in standard nutrient solution (1K) and its modifications without (OK) or surplus (2K) potassium were calculated
from the daily photosynthetic carbon inputs of individual leaves, and the daily respiratory carbon losses by individual leaves,
stalks and petioles, and roots. Under the three K concentrations, maximum net photosynthetic rates (Pn) were found in the 2nd or in the 3rd trifoliate leaves, maximum respiratory rates (Rd) in the youngest, 4th trifoliate leaves; the Pn/Rd ratio decreased with leaf age. In all leaves of 2K plants, leaf dry masses and thicknesses, Pn, Pn/Pd ratios, and stomatal and intracellular conductances were lower than in OK and IK plants. Daily whole-plant net carbon gain
was highest in IK plants, whereas in OK and 2K plants it was 98.0 and 81.3 % of IK, respectively. Similar values were found
in the parameters of growth analysis, namely in net assimilation rates and relative growth rates.
No differences were found in water potential (Ψ
w
) or water saturation deficit (Wsat) in the OK, 1K and 2K plants sufficiently supplied with water or during wilting and resaturation. The decrease in Ψw to −0.97 MPa was associated with a 19.9 %, 31.4 % and 23.4 % decrease in Pn of OK, 1K and 2K plants, respectively, but no effect on Rd was found. In the three variants, the short-time effect of mild water stress was fully reversible. 相似文献
20.
The Susceptibility of Cucumber and Sweet Pepper to Chilling Under Low Irradiance is Related to Energy Dissipation and Water-Water Cycle 总被引:23,自引:4,他引:19
The photoprotection of energy dissipation and water-water cycle were investigated by comparing chilling sensitivity of photosystems
2 (PS2) and 1 (PS1) in two chilling-sensitive plants, cucumber and sweet pepper, upon exposure to 4 °C under low irradiance
(100 μmol m−2 s−1) for 6 h. During chilling stress, the maximum photochemical efficiency of PS2 (Fv/Fm) decreased only slightly in both plants, but the oxidisable P700 decreased markedly, which indicated that PS1 was more sensitive
to chilling treatment under low irradiance than PS2. Sweet pepper leaves had lower Fv/Fm, higher non-photochemical quenching (NPQ), and higher oxidisable P700 during chilling stress. Activity of superoxide dismutase
(SOD) and ascorbate peroxidase (APX) in cucumber leaves was higher, but APX activity decreased apparently compared to that
at room temperature. The productions of active oxygen species (H2O2, O2
−) increased in both plants, faster in cucumber leaves than in sweet pepper leaves. In sweet pepper leaves, a stronger de-epoxidation
of the xanthophyll cycle pigments, a higher NPQ could act as a major protective mechanism to reduce the formation of active
oxygen species during stress. Thus sensitivity of both plants to chilling under low irradiance was dominated by the protective
mechanisms between PS1 and PS2, especially the energy dissipation and the water-water cycle.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献