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1.
In order to study the iron (Fe) distribution pattern in bean plants with different Fe nutritional status, french bean (Phaseolus vulgaris L.) seedlings were precultured in a complete nutrient solution with 8x10‐5 M FeEDTA for five days. Thereafter, plants were further supplied with 8x10‐5 M FeEDTA (Fe‐sufficient) or with only 2x10‐6 M FeEDTA (Fe‐deficient) for another eight days. At this stage, the Fe‐deficient plants had much lower chlorophyll contents and lower dry weight of the leaves but higher reducing capacity of the roots compared with the Fe‐sufficient plants. For studies on short‐term distribution of Fe, the Fe‐sufficient plants were supplied 8x10‐5 M 59FeEDTA (specific activity 9.9 GBq/mol) and the Fe‐deficient plants 1x106 M 59FeEDTA (specific activity 98.8 GBq/mol). The plants were harvested after 4 and 24 hours. Despite a much lower supply of 59FeEDTA/(factor 80), the Fe‐deficient plants took up significantly more 59Fe but translocated less to the shoots (14.6% after 24 h) compared with the Fe‐sufficient plants (29.4% after 24 h). However, regardless of the Fe nutritional status of the plants, the majority of 59Fe was translocated in the primary leaves. Our results demonstrate a similar distribution patterns of root‐derived 59Fe in the shoots of Fe‐sufficient and Fe‐deficient plants, and thus, no preferential direct translocation of Fe to the shoot apex in the Fe‐deficient plants.  相似文献   

2.
Pot-grown tomato plants (Lycopersicon esculentum Mill. cv. Maofen) was used to study the effects of three shading levels (0, 75% and 40%) for 8 days on dry matter partitioning, contents of nitrogen (N),phosphorus (P) and potassium (K) in leaves and yield at three growth stages (early flowering (EF), peak flowering (PF) and later flowering (LF)). Shading reduced the dry weight of root and stem tissues at the EF and PF stages, but the 40% shading increased root dry weight and stem dry weight by 43.2% and 21.6%,respectively, at the LF stage. The influence of shading on the dry weight of leaves was very small at most growth stages. Shading had no effects on total leaf N, P and K contents at the EF and PF stages, showing that N, P and K absorption were regulated by the carbon assimilation at these two stages. The leaf N, Pand K contents of 40% shaded plants at the LF stage were significantly increased. There were no obvious differences in leaf N and K contents between 75% and 40% shading treatments, but significant difference in leaf P contents was found between them at the LF stage. Shading significantly enhanced the friit yield of 40% shaded tomato plants at the LF stage, but failed to affect the fruit yield of shaded plants at the EF stage. These showed that tomato could grow well and a better yield could be obtained if some moderate shading (i.e., 40% shading) was applied at the LF stage at s, mmer midday.  相似文献   

3.
不同供磷水平对饭豆体内铁有效性的影响   总被引：1，自引：0，他引：1  
采用溶液培养试验研究了低铁条件下（1 μmol/L FeEDTA）不同供磷水平P 3、30和300 μmol/L对饭豆叶绿素含量、生物量、铁含量以及质外体铁的影响。结果表明,饭豆叶片叶绿素含量及根系干重均随磷处理浓度的增加而显著降低; 低磷处理的植株地上部的铁含量明显高于中磷和高磷处理。随着供磷水平的增加,地上部和根系总铁量的比值呈降低趋势,说明铁由根系向地上部的转运显著减少,从而加剧了植株缺铁症状。进一步分析发现,低磷处理的根系质外体铁含量显著低于中磷和高磷处理。说明在铁吸收过程中,供磷水平增加促使铁在根系质外体空间中的固定,不利于根系中的铁转运至地上部,这可能是磷是对铁产生拮抗作用造成植物铁营养不利的原因之一。  相似文献   

4.
Barley plants were grown hydroponically at two levels of K (3.0 and 30 mm) and Fe (1.0 and 10 μm) in the presence of excess Mn (25 μm) for 14 d in a phytotron. Plants grown under adequate K level (3.0 mm) were characterized by brown spots on old leaves, desiccation of old leaves, interveinal chlorosis on young leaves, browning of roots, and release of phytosiderophores (PS) from roots. These symptoms were more pronounced in the plants grown under suboptimal Fe level (1.0 p,M) than in the plants grown under adequate Fe level (10 μm). Plants grown in 10 μm Fe with additional K (30 mm) produced a larger amount of dry matter and released less PS than the plants grown under adequate K level (3.0 mm), and did not show leaf injury symptoms and root browning. On the other hand, the additional K supply in the presence of 1.0 μM Fe decreased the severity of brown spots, prevented leaf desiccation, and increased the leaf chlorophyll content, which was not sufficient for the regreening of chlorotic leaves. These results suggested that the additional K alleviated the symptoms of Mn toxicity depending on the Fe concentration in the nutrient solution. The concentration (per g dry matter) and accumulation (per plant) of Mn in shoots and roots of plants grown in 10 μm Fe and 30 mm K were much lower than those of the plants grown in 10 μm Fe and 3.0 mm K, indicating that additional K repressed the absorption of Mn. The concentration and accumulation of Fe in the shoots and roots of the plants grown in 10 μm Fe and 30 mm K were higher than those of the plants grown in 10 μm Fe and 3.0 mm K, indicating that the additional K increased the absorption of Fe under excess Mn level in the nutrient solution. The release of PS, chlorophyll content, and shoot Fe concentration were closely correlated.  相似文献   

5.
The dry weight accumulation per male and female flower as well as the concentration per gram of dry weight and the accumulation of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined in walnut tree (Juglans regia L.) catkins and female flowers at the stage of flower bud and during the flower development. Catkin emergence was accompanied by a very fast hydration of the tissues. After the catkin matured, the fresh and dry weights were reduced. The female flower development period was accompanied by the dry and fresh weight increase. Total N, P, K, Fe, Mn, Cu and Zn concentrations in catkin buds were detected at lower levels, Mg in equal levels, and Ca at higher levels as compared to the nutrient concentrations in young growing leaves. The estimated values of the ratio NCmfb/NCygl were: total N = 0.54, P = 0.83, K = 0.56, Ca = 1.5, Mg = 1.0, Fe = 0.46, Mn = 0.71, Cu = 0.85, and Zn = 0.60. Nutrient concentration in female flower buds was detected in almost equal levels with the exception of total N and Fe. The estimated values of the ratio: NCffb/NCygl were: total N = 0.57, P = 1.1, K = 1.17, Ca = 1.06, Mg = 0.9, Fe = 0.47, Mn = 1.0, Cu = 0.92, and Zn = 0.85. Total N, P, Mn, Cu, and Zn accumulations in the catkin were increased during the fast growing phase and decreased after catkin maturing. Potassium, Mg, and Fe accumulation continued to increase in the mature catkin. Calcium accumulation decreased at a very late mature catkin phase. Total N, P, and K accumulation rates during the catkin fast growing phase were higher than the dry weight accumulation rate. Calcium, Mg, Fe, Mn, Cu, and Zn accumulation rates at the same period were lower or equal to dry weight accumulation rates. In mature catkins, the total N, P, Mn, Cu, and Zn depletion rates were higher than the dry weight depletion rate. The continual increase of K, Ca, Mg, and Fe accumulation in mature catkin resulted in the increase of nutrients concentration also. Total N and P showed the highest remobilization values from mature catkin of 51.4% and 45%, respectively. Calcium, K, Mg, Cu, Mn, and Zn remobilization values estimated to be 22.1%, 7.5%, 3.2%, 45.3%, 33.4%, and 31.8%, respectively. Iron showed no remobilization at all. Nutrients remobilization from catkins as compared to the leaves had almost similar values for total N, Zn, and Cu, higher for P, Ca, and Mn, and lower for Mg, Fe, and K. Accumulation of all nutrients in female flowers increased after fertilization. The dry weight accumulation rate was higher than the nutrient accumulation rates.  相似文献   

6.
Two week‐old summer squash (Cucurbita pepo L.) were transplanted to container volumes of 0.35, 2.00, or 7.60 liters and were grown under full light or 47% shaded conditions to determine the growth and development responses of the crop relative to root and shoot stresses. Light regime had no apparent impact on plant leaf area production; however, leaf area of plants grown under both light regimes was reduced similarly by root restriction. Leaf area reductions were largely attributable to smaller individual leaf sizes. Specific leaf area did not respond to root restriction, but shading increased the amount of leaf area produced per unit of leaf dry weight for all soil volumes. Whole‐plant dry weight reductions due to root restriction were more pronounced in full light than in the shaded environment. There were no consistent differences in the percent of biomass allocated to roots, shoot, or leaves in response to either soil volume or light regime. Also, there were no effects of root restriction or light regime on timing, duration, and sex of flowers, or on timing of fruit set. Fruit dry weights at final harvest were reduced by increased root restriction under full light conditions; however, there were no differences in fruit dry weight among different container volumes under shaded conditions. The results from this study indicate that root restriction does reduce squash growth and yield; however, the effects of shading may be more important.  相似文献   

7.
The development of iron deficiency symptoms (growth depression and yellowing of the youngest leaves) and the distribution of iron between roots and leaves were investigated in different vine cultivars (Silvaner, Riparia 1G and SO4) grown in calcareous soils. As a control treatment all cultivars were also grown in an acidic soil. Only the cultivars Silvaner and Riparia 1G showed yellowing of the youngest leaves under calcareous soil conditions at the end of the cultivation period. All cultivars including SO4 showed severe shoot growth depression, by 50 % and higher, before yellowing started or without leaf yellowing in the cultivar SO4. Depression of shoot growth occurred independently from that of root growth. In a further treatment the effect of Fe‐EDDHA spraying onto the shoot growth of the cultivar Silvaner after cultivation in calcareous soil was investigated. Prior to Fe application plants were non‐chlorotic, but showed pronounced shoot growth depression. Spraying led to a significant increase in shoot length, though leaf growth was not increased. Accordingly, depression of shoot growth of non‐chlorotic plants under calcareous soil conditions and with ample supply of nutrients and water has been evidenced to be at least partly an iron deficiency symptom. We suggest that plant growth only partially recovered because of dramatic apoplastic leaf Fe inactivation and/ or a high apoplastic pH which may directly impair growth. Since growth was impaired before the youngest leaves showed chlorosis we assume that meristematic growth is more sensitively affected by Fe deficiency than is chlorophyll synthesis and chloroplast development. In spite of high Fe concentrations in roots and leaves of the vines grown in calcareous soils plants suffered from Fe deficiency. The finding of high Fe concentrations also in young, but growth retarded green leaves is a further indication that iron deficiency chlorosis in calcareous soils is caused by primary leaf Fe inactivation. However, in future, only a rigorous study of the dynamic changes of iron and chlorophyll concentration, leaf growth and apoplastic pH at the cellular level during leaf development and yellowing will provide causal insights between leaf iron inactivation, growth depression, and leaf chlorosis.<?show $6#>  相似文献   

8.
During a normal growing season, sweetpotatoes shed a substantial number of leaves (Somda and Kays, 1990b). To ascertain the potential cost of leaf loss to the plant, the sequential loss of leaves over the entire growing season was monitored and related to losses of dry matter and individual elements when leaf shedding was induced via leaf shading. The number of leaves produced increased as the season progressed, but missing leaves outnumbered by 21% those remaining on the plant by the end of the growing season. Average dry weights of individual leaves increased progressively to a maximum 14 weeks after planting, and then declined until harvest. After the 6th week, leaf area decreased relative to plant dry weight for the remainder of the growing season. Mature leaves remobilized nearly 37% of their total dry matter prior to abscission; the remaining 63% was lost from the plant, representing an estimated dry matter loss of approximately 2.8 MT/ha during the growing season. A significant portion of P, K, and Mg that had accumulated in mature leaves was recycled into the plant prior to abscission. However, remobilization of Ca, Fe, Zn, Mn, B, Na, and Al was not significant. Leaf shedding in field populations of ‘Jewel’ sweetpotatoes was extensive, and while significant dry matter was recycled out of the leaves prior to abscission, leaf drop represented a substantial loss of P, K, and Mg and dry matter from the crop.  相似文献   

9.
The dry weight accumulation per leaf as well as the concentration per gram of dry weight and the accumulation of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined in walnut tree leaves (Juglans regia L.) during a complete life cycle. Additionally, the dynamics of plant nutrient concentration in leaf petiole sap and carbohydrate accumulation in leaves were studied in relation to the main life cycle events of the walnut tree. Total N, P, K, Cu, and Zn concentrations decreased, whereas that of Ca, Mg, and Mn increased during the season. Iron concentration fluctuated around a mean value. Total N, P, K, Mg, and Cu concentrations detected in younger mature leaves were at the sufficient level, whereas Ca, Fe, Mn, and Zn concentrations were at higher levels as compared to those previously reported. All the detected nutrient accumulations increased abruptly during leaf ontogeny and leaf maturation until a maximum level was attained in the younger mature leaves. Similarly, sucrose, glucose, and fructose accumulation were observed at the same period. The rates of total N, P, Cu, and Zn accumulation were lower than the rates of the observed dry matter accumulation and nutrient concentration dilution. Potassium and Mn accumulation rates were almost equal, whereas those for Ca and Mg were higher as compared to the dry matter accumulation rate. The fast embryo growing phase resulted in a considerable decrease in dry weight, total N, P, K, Cu, Zn, and carbohydrate accumulation, and to a lesser degree in Ca, Mg, and Mn accumulation. Nutrient accumulation reduction in leaves by the influence of the growing fruits were estimated to be: total N 52%, K 48%, P 29.5%, Mg 16.3%, Ca 15%, Fe 51.2%, Cu 55.2%, Zn 37.3%, and Mn 5.4% of the maximum nutrient value of the younger mature leaves. Old leaves preserved nutrients before leaf fall as follows: total N 25.4%, P 45%, K 31%, Ca 74.8%, Mg 76.5%, Mn 89.2%, Fe and Zn 50%, and Cu 37%. Nutrient remobilization from the senescing old leaves before leaf fall were: total N 22.6%, P 25.5%, K 21%, Ca 10.2%, Mg 7%, Fe 3.2%, Mn 5.4%, Cu 8%, and Zn 13.3% of the maximum value in the younger mature leaves. In early spring, the absorption rates of N, P, and Ca were low while those of Mg, Fe, Mn, Cu, and Zn were high. During the fast growing pollen phase, the N, P, Fe, Mn, Cu, and Zn concentrations were reduced. Calcium concentration is supposed to be more affected by the rate of transpiration rather than during the growing of embryo. Calcium and Mg concentrations in the sap were negatively correlated. The detected K concentration level in the sap was as high as 33 to 50 times that of soluble N, 12 to 21 times to that of P, 5 times to that of Ca, and 10 to 20 times to that of Mg. The first maximum of starch accumulation in mature leaves was observed during the slow growing embryo phase and a second one after fruit ripening. Old senescing leaves showed an extensive carbohydrate depletion before leaf fall.  相似文献   

10.
用营养液培养方法研究了在不同供铁条件下不同形态N和韧皮部烫伤对玉米苗期韧皮部Fe运输的影响。结果表明,韧皮部烫伤提高了玉米根系Fe的再利用,降低了初生叶中Fe的再利用,尤其在缺Fe条件下这种作用更明显,提高和降低的幅度更大。韧皮部烫伤还降低了伤流总量,增加了Fe的浓度。在供应铵态N的条件下,Fe的韧皮部运输比供应硝态N条件下有显著增加,Fe的再利用明显提高。  相似文献   

11.
《Journal of plant nutrition》2013,36(8):1381-1393
Abstract

Root and leaf ferric chelate reductase (FCR) activity in Annona glabra L. (pond apple), native to subtropical wetland habitats and Annona muricata L. (soursop), native to nonwetland tropical habitats, was determined under iron (Fe)-sufficient and Fe-deficient conditions. One-year-old seedlings of each species were grown with 2, 22.5, or 45 µM Fe in a nutrient solution. The degree of tolerance of Fe deficiency was evaluated by determining root and leaf FCR activity, leaf chlorophyll index, Fe concentration in recently mature leaves, and plant growth. Root FCR activity was generally lower in soursop than in pond apple. Eighty days after plants were put in nutrient solutions, leaf FCR activity of each species was lower in plants grown with low Fe concentrations (2 µM) than in plants grown with high (22.5 or 45 µM) Fe concentrations in the nutrient solution. Leaves of pond apple grown without Fe became chlorotic within 6 weeks. The Fe level in the nutrient solution had no effect on fresh and dry weights of soursop. Lack of Fe decreased the leaf chlorophyll index and Fe concentration in recently matured leaves less in soursop than in pond apple. The rapid development of leaf chlorosis in low Fe conditions and low root and leaf FCR activities of pond apple are probably related to its native origin in wetland areas, where there is sufficient soluble Fe for adequate plant growth and development. The higher leaf FCR activity and slower growth rate of soursop compared to pond apple may explain why soursop did not exhibit leaf chlorosis even under low Fe conditions.  相似文献   

12.
采用叶片涂抹的方法研究了铁营养状况与不同外源激素对玉米体内铁分配与再利用的影响。结果表明 ,在缺铁条件下 ,外源乙烯利处理玉米植株初生叶可促进初生叶衰老 ,提高初生叶中铁再利用率 ,改善新叶的铁营养状况 ,增加其中的活性铁与全铁含量 ;外源细胞分裂素处理新叶可促进新叶的生长发育 ,提高新叶中全铁及活性铁含量。  相似文献   

13.
Abstract

The essential trace elements Fe, Mn, Zn, Cu, and B in high concentrations can produce phytotoxicities. Iron toxicity resulted from 5 × 10‐4 M and 10‐3 M FeSO4, but not from equivalent amounts of FeEDDHA (ferric ethylenediamine di (o‐hydroxyphenylacetic acid) ). Leaf concentrations in bush beans of 465 μg Mn/g, 291 μg B/g, and 321 μg Zn/g all on the dry weight basis resulted in 27%, 45%, and 34% reduction in yields of leaves, respectively. Zinc was concentrated in roots while Mn and B concentrated in leaves. Solution concentrations of MnS04 of 10‐3 and 10‐2 M depressed leaf yields of bush beans by 63% and 83%, respectively, with 5140 and 10780 μg Mn/g dry weight of leaves. Copper concentrations were simultaneously increased and those of Ca were decreased. Bush bean plants grown in Yolo loam soil with 200 μg Cu/g soil had a depression in leaf yield of 26% (with 28. 8 μg Cu/g leaf); plants failed to grow with 500 μg Cu/g soil. A level of 10‐3 M H2MoO4 was toxic to bush beans grown in solution culture. Leaves, stems, and roots, respectively, contained 710, and 1054, and 5920 μg Mo/g dry weight.  相似文献   

14.
A typical symptom of iron (Fe) deficiency in plants is yellowing or chlorosis of leaves. Heavy metal toxicity, including that of zinc (Zn), is often also expressed by chlorosis and may be called Fe chlorosis. Iron deficiency and Zn toxicity were evaluated in soybean (Glycine max [L.] Merr.) at two levels each of Zn (0.8 and 40 μM), Fe (0 and 20 μM), and sulfur (S) (0.02 and 20 mM). Reduction in dry matter yield and leaf chlorosis were observed in plants grown under the high level of Zn (toxic level), as well as in the absence of Fe. Zinc toxicity, lack of Fe, and the combination of these conditions reduced dry matter yield to the same extent when compared to the yield of the control plants. The symptoms of Zn toxicity were chlorosis in the trifoliate leaves and a lack of change in the orientation of unifoliate leaves when exposed to light. The main symptoms of Fe deficiency were chlorosis in the whole shoot and brown spots and flaccid areas in the leaves. The latter symptom did not appear in plants grown with Fe but under Zn toxicity. It seems that Fe deficiency is a major factor impairing the growth of plants exposed to high levels of Zn. Under Zn toxicity, Fe and Zn translocation from roots to shoots increased as the S supply to the plants was increased.  相似文献   

15.
Evidence clearly shows that cationic micronutrients in spray solutions reduce the herbicidal effectiveness of glyphosate for weed control due to the formation of metal-glyphosate complexes. The formation of these glyphosate-metal complexes in plant tissue may also impair micronutrient nutrition of nontarget plants when exposed to glyphosate drift or glyphosate residues in soil. In the present study, the effects of simulated glyphosate drift on plant growth and uptake, translocation, and accumulation (tissue concentration) of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were investigated in sunflower (Helianthus annuus L.) plants grown in nutrient solution under controlled environmental conditions. Glyphosate was sprayed on plant shoots at different rates between 1.25 and 6.0% of the recommended dosage (i.e., 0.39 and 1.89 mM glyphosate isopropylamine salt). Glyphosate applications significantly decreased root and shoot dry matter production and chlorophyll concentrations of young leaves and shoot tips. The basal parts of the youngest leaves and shoot tips were severely chlorotic. These effects became apparent within 48 h after the glyphosate spray. Glyphosate also caused substantial decreases in leaf concentration of Fe and Mn while the concentration of Zn and Cu was less affected. In short-term uptake experiments with radiolabeled Fe (59Fe), Mn (54Mn), and Zn (65Zn), root uptake of 59Fe and 54Mn was significantly reduced in 12 and 24 h after application of 6% of the recommended dosage of glyphosate, respectively. Glyphosate resulted in almost complete inhibition of root-to-shoot translocation of 59Fe within 12 h and 54Mn within 24 h after application. These results suggest that glyphosate residues or drift may result in severe impairments in Fe and Mn nutrition of nontarget plants, possibly due to the formation of poorly soluble glyphosate-metal complexes in plant tissues and/or rhizosphere interactions.  相似文献   

16.
Two cucumber cultivars (Cucumis sativus L.) exposed to three cadmium (Cd) concentrations (0, 1, and 5 μM) were supplemented or un-supplemented with silicon (Si) (1 mM). Exposure to 1 μM Cd had no effect on shoot and root dry mass, whereas exposure to 5 μM Cd significantly reduced plant growth. Addition of Si stimulated the growth of Cd-treated cucumber. Exposure to 5 μM Cd significantly increased shoot Cd concentration and decreased iron (Fe) and zinc (Zn) concentration. Plants supplied with Si had lower Cd and higher Zn and Fe compared with unsupplied plants. Exposure to Cd resulted in a higher production of malondialdehyde (MDA). Si nutrition partly ameliorated lipid peroxidation induced by Cd toxicity. Activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX), and catalase (CAT) decreased, whereas ascorbate peroxidase (APX) activity increased in response to 5 μM Cd. Induction of APX activity might play an important role in the response of cucumber to Cd toxicity.  相似文献   

17.
Mobility and distribution of lead (Pb) were investigated in cucumber (Cucumis sativus L.) grown in solution culture. Based on the observation that Pb uptake is influenced by the chemical form of iron (Fe) (complexed or ionic) in the solution, Fe distribution was also determined. Iron concentration was even in the stem (separated to internodes) and petioles but slightly increased at the shoot tip while Pb concentration decreased upwards. In the leaves Fe concentration decreased upwards (whereas in the control it increased a little at the youngest leaves) while Pb concentration increased to the largest leaves then decreased towards the shoot tip. It is suggested that the distribution of Pb in cucumber is passive process and it accumulates in the apoplast while Fe distribution is determined by the requirements of synthetic processes in young or photosynthesizing tissues. Lead probably lowers Fe transport into the symplast in the leaves causing slight chlorosis at the youngest leaves. In the plants that were loaded with Pb, decapitated and rooted again in Pb‐free culture solution we found no significant remobilization of Pb which supports that Pb binds strongly to the binding sites in the apoplast or is detoxified in an immobile form.  相似文献   

18.
Both drought and salinity cause nutrient disturbance, albeit for different reasons: a decrease in the diffusion rate of nutrients in the soil and the restricted transpiration rates in plants for drought and extreme soil sodium (Na)/calcium (Ca), Na/potassium (K), and chloride (Cl)/nitrate (NO3) ratios for salinity. The objective of this study was to examine short-term effects of drought and salinity on nutrient disturbance in wheat seedlings. Wheat was grown in a greenhouse in soil under drought and saline conditions for 26 days after sowing. At harvest, shoot biomass and length, and fresh weight and dry weight of the blade and sheath in expanded leaves 3 and 4 and expanding leaf 5 were determined. Mineral elements (K, Ca, magnesium (Mg), phosphorus (P), nitrogen (N), Na, sulphur (S), iron (Fe), zinc (Zn), and manganese (Mn)) in leaf blades and sheaths were also analyzed. At harvest, the reduction in plant height, shoot biomass, and accumulative evapotranspiration under drought was similar to that under salinity as compared with control plants. However, drought decreased the accumulation of all ions in the blade of the youngest leaf 5 compared with the control, whereas there was either an increase or no difference in all ion concentrations under saline conditions. The change in concentration for most ions in the blade and sheath of expanded leaves 3 and 4 varied among control, drought, and salinity plants, which indicated a different competition for nutrients between the sheath and blade of expanded leaves under drought and saline conditions. It can be concluded from this study that ion deficiency might occur in expanding leaves under drought but not saline conditions.  相似文献   

19.
Little is known about the effect of varying levels of potassium (K) on the mineral element concentration, growth, and gas exchange, characteristics of woody ornamental plants. The commercially important woody ornamental species Hibiscus rosa‐sinensis L. cv. Leprechaun was evaluated for K response in a series of three experiments with full strength Hoagland's nutrient solution, which supplied 0 to 10 mM K. Plants grown with 4 mM K in nutrient solution (2.4% leaf tissue K) had the greatest shoot growth and root extension. Gas exchange rates (net photosynthesis, transpiration, and stomatal conductance) were also highest at 4 mM K compared to the control (0 mM K /0.6% leaf tissue K), 0.2, 2.0 and 10 mM K treatments. The application of 4 mM K increased net photosynthesis and tranpiration by 2.1 fold and stomatal conductance by 4.5 fold over 0 mM K controls. Increasing K in nutrient solution correlated positively with tissue K, manganese (Mn), and zinc (Zn), but negatively with nitrogen (N), phosphorus (P), calcium (Ca), and magnesium (Mg). There was a stronger sink for K in yonger leaves (the first to fourth fully expanded leaf from the shoot apex) which had higher K concentration than older leaves (the eighth to twelfth fully expanded leaf from the shoot apex). However, with increasing K in nutrient solution, K concentration in leaf tissue increased regardless of leaf age, and the difference between the younger and older leaf was constant. Daily application of 10 mM K resulted in 6.9% leaf tissue K and caused a decrease in plant total dry matter, net photosynthesis, compared to 4 mM K treated plants. However, these parameters remained higher in 10 mM K plants, which retained high ornamental quality than in 0 mM controls. Plants fertilized with 10 mM K, had the highest leaf tissue K and Zn, but lowest P, Ca, Mg, iron (Fe), copper (Cu) and boron (B). Nevertheless, the 10 mM K treated plants exhibited no morphological differences or deficiency symptoms; rather those plants had similar vegetative vigor and flower bud formation rate as those at 4 mM K.  相似文献   

20.
The accumulation of germanium (Ge) by barley (Hordeum vulgare cv. ‘Arivat') grown at various Ge and pH levels was investigated because Ge is an industrially important metal and bioaccumulation of Ge is a potentially useful means of concentrating this trace metal. Six‐day‐old barley seedlings were grown in perlite and nutrient solution adjusted to a pH of 4.5, 6.0, or 7.5 supplemented with 20, 40,60, or 80 μM Ge for seven days. The plants were divided into roots and shoots after harvesting; the dry weight and Ge content of the individual organs were measured, as was the peroxidase activity in the distal 1 cm of the primary leaves. Barley seedlings accumulated Ge in the roots and shoots; the shoots accumulated Ge linearly as medium Ge concentration increased. The dry weight of the organs was not affected, although necrosis was observed in the primary leaves of the seedlings treated with Ge concentrations greater than 20μM. Peroxidase activity in the primary leaves also increased as the Ge levels in the medium increased which indicated that elevated levels of Ge stimulated leaf senescence. These results demonstrate that barley plants can take up Ge and suggest that Ge is not toxic at the levels that might occur in areas where Ge is normally mined.  相似文献   

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