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1.
Lactuca sativa L. plants were grown at three root-zone temperatures (RZTs): 25°C, 30°C and ambient RZT (A-RZT) on an aeroponic system. Three potassium (K) concentrations: ?25% (minus K), control (standard K), and +25% (plus K) were supplied to plants at each RZT. Plants grown at the plus K and 25°C-RZT had the highest productivity, largest root system and highest photosynthetic capacity. The minus K plants at 25°C-RZT had the highest shoot soluble carbohydrate (SC) concentration, but they had the highest root SC concentration in the plus K plants at A-RZT. However, the highest starch concentration was found in both shoots and roots of the plus K plants at 25°C-RZT. The plus K plants had the highest shoot K concentration at 25°C-RZT, but they had the highest root K concentration at A-RZT. Highest proportion of absorbed K was partitioned to shoots when the plants were grown with the plus K at 25°C-RZT.  相似文献   

2.
Siberian C peach seedlings (Prunus persica L. Batsch) were grown for 35 days in all combinations of Long Ashton nutrient solution containing P concentrations of 0.05, 0.5, or 5.0 mM and root zone temperatures (RZT) of 8°C, 16°C, and 24°C. At harvest, a significant interaction between solution P concentration and RZT occurred for shoot and root dry weight, root length, shoot P concentration and shoot P uptake. At 8°C RZT, P concentration and uptake but not growth were increased by P. At 16°C and 24° C RZT, growth was depressed at the 5.0 mM P level with shoot P concentration and uptake lower at 24°C than 16°C. The inflow of P to the peach shoot per unit root length was increased at high P concentration and low temperatures but was lower than whole plant inflow rates for apples. The growth depression at high temperature‐high P was related to increased young leaf chlorosis, reduced shoot Fe and a possible P/Zn imbalance.  相似文献   

3.
Root growth and nutrient uptake rates of maize (Zea mays L.) are decreased at low root zone temperatures (RZT) and thus, shoot growth may be limited by nutrient deficiency. The objectives of this research were to characterize the shoot demand for nutrients per unit root at suboptimal RZT and to relate net translocation rates of N, P, K, and Ca from the roots to the shoot to shoot demand. Maize plants were grown for 11 days in soil or 8 days in nutrient solution at uniform shoot (24°/20°C, day/night) but different RZT (12°, 18°, and 24°C). The shoot base of the plants (apical shoot meristem and zone of leaf extension) was either kept within or above the cooled root zone. Shoot and root growth were significantly reduced at suboptimal RZT (12°, 18°). Lifting the shoot base above the cooling zone increased shoot growth markedly, whereas root growth was not significantly influenced. Thus, the shoot fresh weight increment day?1 g?1 root fresh weight (i.e. the shoot demand per unit root) was increased by a factor of up to 9 for plants with their shoot base above as compared to within the cooling zone. At suboptimal RZT, translocation rates of N, K, and Ca to the shoot remained low in plants with the shoot base in the cooling zone but were higher than in 24°C-grown plants, when the shoot base was above the cooling zone. In both nutrient solution- and soil-grown plants translocation rates of N, K, and Ca were closely correlated with the shoot demand per unit root but less to RZT. In contrast, the translocation rate of P was mainly affected by RZT but insensitive to shoot demand and, therefore, was always higher at a RZT of 24° than of 12°C. From these results it is suggested, that at low RZT the root-to-shoot translocation rates of N, K, and Ca are mainly determined by the shoot demand, whereas the translocation rate of P, regardless of the shoot demand, is reduced by a direct effect of low temperature on the roots.  相似文献   

4.
In nitrate-fed plants cycling of nitrogen (N) and potassium (K) may serve several functions including supply of the roots with nutrients needed for growth, signalling of the growth-related shoot demand for nutrients to the roots, and removal of excess K from the shoot. In the present study, cycling and recycling of N and K were estimated in plants showing different rates of shoot and root growth. To induce these variations in growth, the plants were cultured with the same optimal nutrient supply but with the root zone temperature (RZT) at 12°C or 24°C. Additionally at both RZT, the plants were grown with their shoot base including apical shoot meristem at high or low temperature (SBT). Decreasing the RZT to 12°C drastically diminished root growth and accumulation of N and K in the roots. Cycling of N and K were less reduced by low RZT. At both RZT, N and K cycling were markedly reduced at low in comparison to high SBT although root growth was not affected by the SBT. Obviously, N and K cycling from shoot to roots were more affected by shoot growth than by the growth related demand of the roots for nutrients. At both RZT, N and K cycling exceeded accumulation in the roots. It was estimated that at least 20—33% of the N, and 24—51% of the K translocated from the roots to the shoot in the xylem is not directly derived from root uptake but from cycling. Plant culture at low shoot base temperature (SBT) drastically diminished shoot growth, and the accumulation of N and K in the shoot to less than 50% of the values measured in plants grown at high SBT. The low SBT-induced decrease of N accumulation in the shoot, at both RZT was associated with a reduction of K circulation and recirculation rates to less than 50% of those found in plants grown at high SBT. These findings are in accordance with the suggested role of K+ for charge balance facilitating the transport of NO3— in the xylem and disposal of the negatively charged products of NO3— assimilation from shoot to roots in the phloem. In plants cultured at low SBT, net uptake and translocation rates of N and K were diminished to less than 50% of those measured in plants grown at high SBT. This repression was associated with reduced rates of N and K cycling from the shoot to the roots. Obviously, low rates of N and K cycling from the shoot to the roots are not necessarily signals to increase uptake in the roots. It is suggested that for plants adequately supplied with N, high rates of N cycling and recycling might be the consequence of an apparent lack in control of phloem loading of amino acids in the leaves.  相似文献   

5.
Abstract

Oilseed rape (Brassica napus) is sensitive to low boron (B) supply, and its growth response to B may be influenced by soil temperature. To test the relationship between B and temperature, oilseed rape (cv. Hyola 42) seedlings were grown at 10°C (low) root zone temperature (RZT) with B supply from deficient to adequate B levels until growth of low B plants just began to slow down. Half of the pots were then transferred to 20°C (warm) RZT for 11 days before they were moved back to 10°C RZT for the final 4 days. Both plant dry mass and B uptake increased after plants were exposed to warm RZT. However, plant B deficiency was exacerbated by warm RZT in low B plants because of increased relative growth rate and shoot–root ratio without a commensurate increase in B uptake rate. It is concluded that RZT above the critical threshold for chilling injury in oilseed rape can nevertheless affect the incidence of B deficiency by altering shoot–root ratio and hence the balance between shoot B demand and B uptake.  相似文献   

6.
The zinc (Zn) requirement of a maize (Zea mays L.) hybrid (‘FHY-396’) and an indigenous variety (‘EV-7004’) was measured at low (22.4 ± 5°C) and high (28.8 ± 5°C) root-zone temperatures (RZT). Four Zn rates (0, 3, 9 and 27 mg kg?1 soil) were applied to a calcareous loam soil in pots for the glasshouse study. Shoot and root dry matter yields were significantly more at the higher RZT. Regardless the RZT, maximum relative shoot dry matter yield in hybrid and variety was produced, respectively, at 9 and 3 mg Zn kg?1 soil. Zinc concentration in roots and shoots of both the cultivars increased with Zn rates and it was significantly more at the higher RZT. Cultivars differed in critical Zn concentration (CZnC) required for maximum shoot dry matter yield. The CZnC ranged from 25 to 39 μg Zn g?1 plant tissue for optimum growth of both the cultivars at low and high RZT.  相似文献   

7.
Radiophosphorus (32P) and hydroponically‐grown bush bean were used to study P absorption kinetics as affected by root zone temperature (RZT) and iron (Fe). Phosphorus uptake increased significantly (p < 0.05) at each successive 10°C rise in RZT from 15 to 35°C, and quadratic regression equations were highly correlated (R2 = 0.98) between the uptake amount and exposure time. An estimated Q10 value of 1.5, and the corresponding Arrhenius constant μ of 31 kJ/mol for P uptake were within range for a diffusion process in an aqueous solution. A concentration of 5 μmol/L Fe significantly (p < 0.05) reduced P uptake from 6 h on at the RZTs studied, and Q10 and μ values were estimated at 1.2 and 14 kJ/mol, respectively.  相似文献   

8.
Abstract

The weekly nitrogen (N), phosphorus (P), and potassium (K) release from 17 polymer‐coated controlled‐release fertilizer (CRF) formulations of Nutricote, Apex Gold, Osmocote, and a 9‐month Macrocote were measured at 30.6±0.8°C and 40.0±1.5°C. Five grams of each CRF were placed at a depth of 50 mm in 280x50 mm acid washed then rinsed silica sand columns which were leached with deionized water three times each week until nutrient recovery ceased. The volume of leachate was recorded each week and subsampled for ammonium‐N, nitrate‐N, phosphate‐P, and K analyses. Each CRF treatment was replicated three times at each temperature. Nutrient release profiles were determined. Longevities, measured as weeks to 90% nutrient recovery, were considerably shorter than the nominated release periods for all formulations. Within each CRF product group, the longevity of 9 and 12 month formulations were similar with Apex Gold 12–14 month high nitrate having the longest (38 weeks for N at 30°C) and Osmocote 8–9 month the shortest (23 weeks for N at 30°C). There were consistent trends in the nutrient release periods across all CRFs with P>K>N and with differences of around 10% in duration between nutrients. The P:N release ratio exceeded 0.10 for most CRFs during the early release period indicating an adequate P supply for most plant species. The mean reduction in longevity for Nutricote, Apex Gold, and Osmocote formulations for an increase in incubation temperature from 30°C to 40°C was 19–21 % for N, 13–14% for P, and 14–15% for K. All CRFs released nutrients unevenly with the highest rate occurring during the early part of the release period. This pattern was accentuated at 40°C and by the shorter term release formulations. The nutrient release rates of all CRFs declined steadily after their maxima.  相似文献   

9.
A nutrient solution experiment was done to evaluate effects of different concentrations of nitrogen (N), phosphorus (P) and potassium (K) on leaf mineral concentrations and some enzymes activity of melon seedlings (Cucumismelo var. inodorus subvar. Khatouni). Different levels of these nutrients including 0, 53, 105, 158 and 210?mg L?1 N; 0, 8, 16, 23 and 31?mg L?1 P; 0, 59, 118, 176 and 235?mg L?1 K, all corresponding to 0, 25, 50, 75 and 100% of their concentrations in Hoagland nutrient solution, were applied to plants. The results showed that the highest leaf nitrate reductase (NR) activity was observed at highest N and P levels, whereas the three highest K levels showed the highest NR activity. The highest leaf peroxidase activity was observed at 8?mg L?1 P, 59?mg L?1 K and 158?mg L?1 N. The leaf catalase activity was highest at zero concentration of P, 158?mg L?1 N and 176?mg L?1 K; however, catalase activity was decreased by increasing P levels. Leaf protein content showed an increasing trend with increasing N, P and K levels of nutrient solution, while there was no significant difference between 158 and 210?mg L?1 N. The highest leaf concentrations of N, P, K and Mg were observed at highest nitrogen, potassium and phosphorus levels of nutrient solution, whereas the highest leaf concentration of Ca were obtained at 53 or 105?mg L?1 N, 176?mg L?1 K and 23–31?mg L?1 P. The highest iron concentration of leaves was obtained from 23 to 31?mg L?1 P, 176?mg L?1 K and 210?mg L?1 N.  相似文献   

10.
To identify the best combinations of micronutrient-based fertilization treatments in terms of crop yield and nutrient uptake, three field experiments with greengram?fingermillet as the test sequence with 12 treatments on micronutrient-based fertilization [with recommended nitrogen (N)?phosphorus (P)?potassium (K) fertilizer] were conducted during 2005 to 2007 in a semi-arid Alfisol at Bangalore. The effects of treatments on available soil and plant uptake of nutrients [N, P, K, sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), boron (B), and molybdenum (Mo)] and yield of crops were assessed based on standard analysis of variance procedure. Using the relationships of yield with soil and plant nutrient variables, regression models of yield through soil and plant variables were calibrated and effects of variables on crop yields were assessed. The models gave high and significant yield predictability in the range of 0.87 to 0.98 through different variables. The model of plant uptake through soil nutrients indicated that soil S, Fe, and Zn had significant positive effects, whereas soil N, K, B, and Mo had negative effects on plant nutrient status in greengram. Similarly, soil P, Mn, and Zn had significant positive effects, whereas soil N, K, and Fe had negative effects on plant uptake of nutrients in fingermillet. Based on a relative efficiency index (REI) criteria, T2 for plant uptake and T12 for maintaining soil nutrients were found to be superior in greengram, whereas T2 for plant uptake and T8 for maintaining soil nutrients were found to be superior in fingermillet over years based on REI. The combined REI over soil and plant nutrients for both crops indicated that application of T8 for greengram and T2 for fingermillet could be prescribed for attaining maximum plant uptake of nutrients and productivity of crops in sequence, apart from maintaining maximum soil fertility of nutrients under semi-arid Alfisols.  相似文献   

11.
Abstract

Nitrogen fertilization and tillage practices may influence the availability and uptake of essential plant nutrients other than N. This study was conducted to assess the interactive effects of N rate and timing and tillage practices on uptake and concentration of P, K, Ca and Mg in corn grown under dryland conditions. Potassium accumulations in no till (NT) soils were greater than in conventional till (CT) near the surface and lower than CT in the subsoil. Phosphorus and Ca levels decreased with soil depth, while Mg tended to accumulate in the subsoil. Phosphorus uptake and concentration of 5‐leaf stage corn was increased as tillage intensity decreased. Nitrogen rate at planting increased 5‐leaf P uptake but reduced P concentration; however, by silking no effect of tillage or N fertilization practice on ear leaf P concentration was obtained. Increases in 5‐leaf corn K uptake and concentration as tillage intensity decreased may have reduced Mg and Ca concentrations via cation antagonism. Ear leaf Mg and Ca concentrations were increased by N rate, probably as a result of solubilization of Ca and Mg and improved crop growth. Distribution of essential elements in the soil due to tillage in combination with varying N fertilization practices can influence temporal nutrient uptake, thereby altering plant nutrient diagnosis.  相似文献   

12.
不同水、氮供应条件下夏玉米养分累积动态研究   总被引：21，自引：11，他引：21  
在遮雨棚内进行了微区试验,采用不同水、氮素供应研究了玉米N、P、K吸收累积动态。结果表明,植株生物量和N、P、K吸收量,随生育期延长而持续增加;而植株的N、P、K含量,则呈下降趋势。植株生物量和N、P、K吸收量随时间的变化,可用S曲线方程描述。玉米生长期间干物质与养分吸收并非同一速率,前期上升快,至最高峰后缓慢下降。在N、P、K三要素中,N、K吸收速率高,上升快,下降也快;P吸收速率低,上升慢,下降亦慢。养分最大吸收速率出现的时间以K最早,N次之,P最晚。但三者均早于干物质最大累积速率出现的时间。水分和氮素供应增加养分最大吸收速率及养分吸收量,也可增加生育前期的养分含量,但不改变养分累积变化趋势和养分吸收速率的变化趋势。水分和氮素供应促进了营养体养分向子粒的运转,提高了养分在子粒中的分配比例,从而提高了子粒产量。  相似文献   

13.
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14.
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15.
Abstract

This analysis establishes linkage among (a) applied nutrients nitrogen (N), phosphorus (P), and potassium (K), (b) available soil nutrients, (c) root dry matter and nutrient content, (d) top dry matter and nutrient content, and (e) leaf area and carbon dioxide (CO2) concentration. It was previously shown that (a) and (d) are coupled by logistic equations with a common response coefficient c between dry matter and plant nutrient uptake with each applied nutrient. As a consequence of the common c, it has been shown that dry matter and plant nutrient removal are coupled by a hyperbolic equation. Furthermore, a model has been developed which includes N, P, and K as inputs. In the present work, (a) and (b) were coupled by a logistic equation as were (a) and (c). It was then shown that plant nutrient removal was coupled to available soil nutrients through a hyperbolic equation. The hyperbolic relationship was also shown to link dry matter between roots and tops, as well as plant N removal between roots and tops. As a consequence of the results above, it was then concluded that root nutrient content is related to available soil nutrient through a hyperbolic equation. The detailed mechanism of this coupling was not identified. Leaf area of soybeans followed a hyperbolic relationship with CO2 concentration in the canopy.  相似文献   

16.
The effects of different temperature treatments during the seedling stage on growth and nutrient absorbance of Gerbera jamesonii cv ‘Sunshine Coast’ growing in the organic substrate were investigated. The temperature treatments were conducted in growth chamber where the day/night temperature were set to 15/10, 20/15, 25/20, and 30/25°C individually. The results showed that the fresh and dry weight of aboveground part and that of roots, average number of leaves and lateral roots were greater at 30/25°C than other treatments. The highest level of macro elements nitrogen (N), phosphorus (P), and potassium (K) in the leaf samples were also detected at 25/20°C and 30/25°C. However, there was no significant influence of different temperatures on zinc (Zn) levels in leaves. In general, the day temperature 25～30°C and night temperature 20～25°C are thought to be the better temperature condition for gerbera growth as well as the nutrient uptake and accumulation in the plants during the seedling stage.  相似文献   

17.
A field study was made of the seasonal changes in dry‐matter production, and the uptake, distribution, and redistribution of 12 mineral nutrients in the semi‐dwarf spring wheat, Egret, grown under typical irrigation farming conditions. Most of the dry‐matter production and nutrient uptake had occurred by anthesis, with 75–100% of the final content of magnesium (Mg), copper (Cu), chloride (Cl), sulfur (S), phosphorus (P), nitrogen (N), and potassium (K) being taken up in the pre‐anthesis period. The above‐ground dry‐matter harvest index was 37%, and grain made up 76% of the head dry matter. Redistributed dry matter from stems and leaves could have provided 29% of the grain dry matter. Concentrations of phloemmobile nutrients, such as N and P, decreased in the leaves and stems throughout the season, whereas concentrations of phloem‐immobile nutrients, such as calcium (Ca) and iron (Fe), generally increased. The decline in the N concentration in stems and leaves was not prevented by N fertilizer applied just before anthesis. Leaves had the major proportion of most nutrients in young plants, but stems had the major proportion of these nutrients at anthesis. Grain had over 70% of the N and P, and 31–64% of the Mg, manganese (Mn), S, and zinc (Zn), but less than 20% of the K, Ca, sodium (Na), Cl, and Fe in the plant. Over 70% of the N and P, and from 15 to 51% of the Mg, K, Cu, S, and Zn was apparently redistributed from stems and leaves to developing grain. There was negligible redistribution of Ca, Na, Cl, Fe, and Mn from vegetative organs. Redistribution from stems and leaves could have provided 100% of the K, 68–72% of the N and P, and 33–48% of the Zn, Cu, Mg, and S accumulated by grain. It was concluded that the distribution patterns of some key nutrients such as N, P, and K have not changed much in the transition from tall to semi‐dwarf wheats, and that the capacity of wheat to redistribute dry matter and nutrients to grain is a valuable trait when nutrient uptake is severely restricted in the post‐anthesis period.  相似文献   

18.
Critical concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and manganese (Mn) with respect to dry matter yield end antagonistic and synergistic relationships among these nutrients were studied in which tomato (Lycopersicon esculentum L.) was grown in recirculating nutrient solution (NFT). Increments of nutrient elements in the nutrient solution increased the proportional rate of the corresponding nutrient elements. Increasing levels of N negatively correlated with plant P and positively correlated with Ca, Fe, and Zn. Iron and Mn contents of the plants were increased and N, K, Ca, and Mg were decreased as a function of P applied. Increases in K in the nutrient solution caused increases in the concentrations of K, N, P, and Zn, and decreases in the concentration of Ca and Fe. Applied Ca increased the concentrations of Ca and N, and decreased the concentrations of P, Mg, Fe, Zn, and Mn. Potassium, Ca, and Fe contents of the plants were decreased and Zn increased, while N, P, and Mn were not affected by the increasing levels of external Mg. Iron suppressed the plant Mg, Zn, and Mn contents. Synergism between Zn and Fe was seen, while P, K, Ca, Mg, and Mn contents were not affected by Zn levels. Potassium, Ca, Mg, and Fe were not responsive to applied Mn, however, N and P contents of the plants were decreased at the highest levels of Mn.  相似文献   

19.
The effect of pyrolysis temperature on the nutritional quality of agricultural biochar is unclear, so better understanding of its properties and how it affects soil nutrient availability and plant growth is needed. Biochars obtained at different pyrolysis temperatures (250, 300, 350 and 400 °C) were characterized by thermogravimetric analyser and Fourier transform infrared spectroscopy. Biochars were applied at a rate of 10 g/kg to find out their effects on the mineral nutrition and growth of lettuce. The experimental results suggested that high biochar temperatures caused oxidation of the mineral elements, breaking of C–C and C–H bonds and removal of aliphatic and peptide groups from the pyrolysed materials. The total concentrations of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn) and boron (B) were increased by increasing pyrolysis temperatures, although water‐soluble concentrations of those elements were greatly reduced (with the exception of K and B). Compared to the control, dry weights of lettuce and maize crops were significantly increased by the biochar treatments obtained at 300 and 350 °C. Biochar treatments significantly increased the P and K concentrations of both plants compared to the control, while concentrations of Ca and Mg in lettuce plants were decreased. Iron, Mn and B concentration of the lettuce plants were reduced and Zn concentration of maize increased by the biochar treatments. It was concluded that in terms of an agricultural product, biochars produced at low temperature are better.  相似文献   

20.
红芸豆养分限制因子及养分吸收、积累和分配特征研究   总被引：1，自引：2，他引：1  
研究红芸豆养分限制因子、植株干物质和氮、磷、钾养分积累及分配规律,可为红芸豆合理施肥及高产栽培提供理论依据。大田试验条件下,以‘英国红’红芸豆为试材,设置缺素试验,采集全施肥区植株样品,分析研究红芸豆不同生育时期各器官干物质量、养分含量及积累量。结果显示,氮磷钾配合全施显著提高红芸豆产量;缺氮、缺磷、缺钾处理与全施肥处理相比,产量分别降低14.2%、8.0%和11.3%,表明影响红芸豆产量的限制因子为氮钾磷。在整个生育期,红芸豆干物质累积速率先升高后降低;根、茎、荚皮和豆粒干物质累积量呈上升趋势,叶干物质在收获期有下降趋势,收获时不同部位干物质量为豆粒茎≈荚皮叶片根。随生育期推进,茎、叶和荚皮中氮含量呈递减趋势,豆粒中氮含量呈递增趋势,而各器官磷、钾含量呈递减趋势。盛花期到结荚期是养分累积最大期,其氮、磷、钾吸收量分别占整个生育期吸收总量的28.14%、49.22%和56.20%;不同器官吸收累积氮、磷、钾量不同,成熟期豆粒、叶、茎和根中均为累积氮最多、钾次之、磷最少,荚皮中累积钾最多、氮次之、磷最少。每生产100 kg红芸豆需供给N 4.37 kg、P2O5 2.38 kg、K2O 3.53 kg,比例为1∶0.54∶0.81。  相似文献   

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