In the first experiment, sunflower was grown in nutrient solutions containing four levels of P(1.5, 2.5, 3.5 and 4.5 mM/l) and three levels of Fe(0.25, 0.75, and 1.5 ppm) as FeCl3 or FeEDDHA. In the second experiment (following the first experiment), the treatments were three P levels (0.75, 1.50 and 3.00 mM/l), three Fe levels (0.25, 0.75 and 1.5 ppm) as FeEDDHA and three Zn levels (0.1, 0.2 and 0.4 ppm).
The plants receiving Fe‐chelate, except for 0.25 ppm Fe, showed no symptoms of iron chlorosis. With inorganic Fe treatments, iron chlorosis appeared after 7–10 days depending on P level, but except for 0.25 ppm Fe which remained chlorotic, plants recovered completely within 3–4 days thereafter due to pH regulating mechanism of sunflower under iron stress condition. With both sources of Fe, chlorosis was associated with high P:Fe ratio.
Increased P and Fe levels in nutrient solution resulted in general increases in the dry weights of roots and shoots. The Fe concentration of shoots, except in few instances, was not affected by P levels, indicating that the sunflower cultivar used in this experiment could utilize inorganic Fe as well as Fe‐chelate under our experimental conditions.
Increasing P levels caused significant increases in Mn content of the shoots as 0.25 and 0.75 ppm inorganic Fe3+. Increased Fe levels increased shoot Mn content with inorganic Fe and decreased it with Fe‐chelate. The effects of P, Fe and Zn on sunflower indicated an antagonistic effect of Zn on 1.5 ppm Fe for all P levels. Increased Zn levels in nutrient solution generally increased Zn content of the shoots without having any marked effect on their Mn content. 相似文献
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. 相似文献
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. 相似文献
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. 相似文献
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). 相似文献
After nutrient solutions were renewed on days 26 and 34, plant‐induced pH patterns were similar to those during days 1 to 26. However, the time required for the onset of the rapid rise in pH decreased. In these subsequent pH cycles, the pH patterns induced by Al‐tolerant plants grown with Al progressively approximated those induced by plants grown without Al. Aluminum‐sensitive plants grown with Al did not induce a rapid rise In pH of nutrient solutions.
Differential tolerance to Al was apparent visually after three to five days growth. Cultivar tolerance to Al was correlated with the initial rate of the pH decline (days 1 to 26) as well as final pH of solutions discarded on days 26, 34, and 41. These results support the hypothesis that differential uptake of NH4 + and NO3 ‐ causes cultivar differences in plant‐induced pH of nutrient solutions and affects the relative growth of cultivars in Al‐toxic nutrient solutions. 相似文献
Our findings showed that i) VWC had a larger influence on N2O and CH4 emissions than WFPS, ii) soil type influenced the gas release into atmosphere or soil solution and the timing of sink to source transition in CH4 emissions. Further investigation on timing of fertilization and drainage are needed to improve climate change mitigation strategies. 相似文献
At the 8‐leaf stage, sorghum plants subjected to 25C were significantly higher in concentration of N, P, K, Mg, and Cu, but were significantly lower in Ca. Soil temperature did not significantly affect concentration of Zn, Fe, and Mn. At the 12‐leaf stage, sorghum plants grown in the warm soil temperature treatment were lower in concentration of N, K, Ca, Mg, Zn, Fe, Mn, and Cu than plants grown in the cooled‐soil treatment. Phosphorus showed a negative response to increased temperature.
It was concluded that further research relating element uptake and translocation to temperature is needed. Element accumulation in the roots, stems, leaves, and floral and seed portions of the plant should be included. In addition, the interaction between plant age and element concentration should be studied more thoroughly. Both this study and the published literature indicate that this interaction is significant for many of the elements. 相似文献
Sunflower plants were grown in nutrient solution with four levels of salinity (0, 1.5, 3.0 and 4.5 atm), induced by NaCl and four rates of Fe chelate (0, 0.5, 1.0 and 1.5, ppm Fe) as FeEDDHA. The experiment was a completely randomized design with treatment combinations arranged in a factorial manner with three replications.
Dry matter yield, shoot‐root ratio, leaf area, plant height and transpiration decreased as salinity increased, the effect of salinity being depressed by iron applications. Salinity reduced P, K, Ca and Mg uptake by roots as well as that of N, P, K, Ca, Mg by shoots, while Fe applications increased uptake of these elements in roots and shoots. Both salinity and iron applications increased Cl, Na and Fe uptake by roots and shoots, as expected. In most instances salinity reduced uptake of Fe, Mn and Zn by the plants while iron applications improved uptake of these elements.
The sunflower plant used in this experiment was found to be, at least partly, tolerant to salinity and decreased water availability as well as toxicity of ions. Nutritional disorders were the cause of decreased plant growth by increasing salinity of the nutrient solution. The decreased plant growth and mineral uptake, induced by salinity, were partially offset by increased iron levels in the nutrient solution. 相似文献
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. 相似文献
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. 相似文献
The concentration of Zn in the leaves of Mn‐sensitive WC‐2 increased significantly with increasing Mn concentration in the solution, but such levels were not toxic to the plants.
The percent distribution of Zn and K in Mn‐sensitive WC‐2 plants (% of total uptake) significantly increased in the tops and decreased in the roots with increasing Mn concentration in the nutrient solution; however, Mn treatment had no effect on distribution of either Ca or Mg in WC‐2. External Mn concentration had little or no effect on the K, Ca, or Mg concentration in the tops of Mn‐tolerant GL. 相似文献
At pH 4 in the presence of plant roots, reduction of iron(III) to iron(II) occurred as indicated by Fe2+ BPDS formation. BPDS in a 3:1 ratio to iron(III) suppressed iron uptake by about 70%. The reduction was observed to be located in the endodermis of young roots and exodermis of older roots.
A capacity to oxidize iron(II) at the root surface was also observed under local anaerobic and relatively high pH conditions.
The significance of these two counteracting processes in affecting the oxidation state of iron at the root surface is discussed. 相似文献
In pea, NRA was maximum at pod maturity stage and minimum at flowering stage. In sorghum plant there was gradual increase in NRA upto grain formation followed by a fall in activity at maturity.
Nitrogen treatment as nitrate and ammonia significantly increased nitrate reductase activity over control in both pea and sorghum. Treatment with potassium nitrate was found to stimulate more NRA in pea than with ammonium sulphate. In sorghum, both forms of nitrogen did not differ much in their influence on NRA.
Influence of moisture stress in reducing NRA was more clear in sorghum, a C4 plant than in pea, a C3 plant. In general, control plants recorded low NRA in both the crops when compared to nitrogen treated plants except at pod formation stage in pea. 相似文献
Cotton (Gossypium hirsutum L.) plants grown in normal (control) and NaCl treated Hoagland solutions were analyzed for distribution of N15 in NH+ 4 plus amide‐N, free α‐amino‐N, total soluble‐N and protein‐N after the plants were provided 15NH4NO3 in nutrient solutions for 6, 12 and 24 h. The concentration of protein‐15N was enhanced under a low level of NaCl (‐0.4 MPa osmotic potential) at the vegetative growth stage. The difference between the protein‐15N concentration of the moderately salinized (‐0.8 MPa) plants and the controls was not significant. A high level of NaCl (‐1.2 MPa) significantly decreased protein‐N content of plants compared with the controls and any other level of salinity. The NaCl increased accumulation of NH4 + plus amide‐N, free (α‐amino‐N, and total soluble‐N in cotton shoots, at both stages of growth. Low osmotic potential (high osmotic pressure) of the nutrient solution induced by excessive amounts of NaCl in nutrient solution inhibited NH+ 4 metabolism and decreased protein synthesis, thus resulting in accumulation of soluble N‐compounds. The ionic effect probably contributed also to inhibition of protein synthesis. 相似文献
The influence of N fertilization on the growth and yield of strawberry plants has been studied by several workers. In some reports yields were increased when the rate of N applied was increased (1, 2, 3). In other studies no influence was found (4, 5, 6), or even a decrease in yield was reported as the rate of applied N was increased (7). While in some studies detrimental effects of N‐fertilizer on fruit yield were observed at 200–300 kg N/ha (8, 9), in other studies (6, 7) N applications up to 400 kg/ha did not affect yield. In Spain (3), adding up to 680 kg/ha caused an increase in fruit yield.
Even at relatively low applied‐N levels, up to 150 kg N/ha, strawberry response reports are not consistent. Some workers found that increasing N in this range caused an increase in fruit yield (8, 9, 3, 7, 10), while no effect was observed (4, 5, 6, 11) in several other studies. Most of the reported experiments with N‐fertilizer were carried out after plants were transplanted from the nursery to the field. To the best of our knowledge no attempt was made to evaluate the effect of fertilizer applied in the nursery.
The objective of this work was to evaluate the influence of different levels of N‐fertilizer, in both the nursery and the field, on strawberry plant development and composition, earliness, yield level and yield distribution. 相似文献
In busbean leaves invertase activity decreased while sucrose increased. K+ with Cl‐ as counterion was most effective “in vivo”;. However, there was little change in invertase activity or sucrose content in sugarbeet leaves. Independent of the origin of the enzyme, invertase activity was not affected by either ion concentration or ion combination “in vitro”;. Acid invertase might be a key enzyme in the utilization of carbohydrates. The ionic effect on acid invertase activity and carbohydrate content in intact plant tissue could be a possible indicator of salt tolerance of crops. 相似文献
Starch and sucrose accumulation is rapidly stimulated in leaves of Dandara, particularly due to extreme potassium sulfate supply, while in Giza 45 the amount of starch and sucrose declines except for extreme potassium sulfate treatment. The low sucrose value in roots of Dandara increases extremely, especially as a result of potassium chloride treatment. In contrast, the higher sucrose content in roots of Giza 45 is little affected. Amylase activity changes considerably in positive correlation with the starch content, whereas the low specific activity of phosphorylase is little affected. The sucrose content in the leaves is directly controlled by a high level of invertase activity of both cotton varieties.
Possible interactions of carbohydrate metabolism and genotyplcal ion regulation in response to the different salt tolerance of the genotypes are discussed. It is concluded that genotypical differences in the carbohydrate metabolism could be effective mechanisms for salt tolerance in cotton. 相似文献
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. 相似文献
The rate of B uptake per g root dry weight was greater in plants having higher transpiration rates; whereas the rate of B translocation to shoots per g dry weight was independent of transpiration rate. Thus we propose that B translocation to shoots is controlled mechanistically by rates of dry matter accumulation during stages of rapid growth, i.e. a sink effect. 相似文献