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1.
The effects of varying fertilizer application rates [100–15–100 or 300–46–300 mg L ‐1 of nitrogen (N)‐phosphorus (P)‐potassium (K)] and pinching dates on nutrient uptake patterns of poinsettias were studied. During the first seven weeks after potting, varying the N‐P‐K fertilization rate from 100–15–100 to 300–46–300 mg L ‐1 N‐P‐K had no effect on plant height, dry weight, nutrient concentration, or nutrient content of poinsettias. The uptake ratios for NO 3‐N, K, calcium (Ca), and magnesium (Mg) all were <40% of the amount that was available at the 100 mg L" 1 N and K fertilization rate, indicating that poinsettias require lower levels of NO 3‐N, K, Ca, and Mg than what was available from the 100–15–100 mg L" 1 N‐P‐K fertilization rate. The higher uptake ratios of >60% and >70%, respectively, for NH 4‐N and P at the 100 mg L" 1 N and K fertilization rate indicated the plants utilized a higher percentage of the available NH 4‐N and P, indicating that an application rate >18 mg L ‐1 NH 4‐N and >15 mg L ‐1 P would be required by poinsettias from the week before the plants were pinched through three weeks after pinching. The 300–46–300 mg L ‐1 N‐P‐K fertilization rate provided excessive nutrients that were not utilized by the plants during the early stages of plant growth. 相似文献
2.
Plant growth and metabolism is impaired under stress conditions, resulting in decreased crop yields. The purpose of this investigation was to evaluate the NaCl stress effects on NH + 4 metabolism in cotton plants at vegetative and reproductive stages of growth. 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
3.
The growth of sesame (Sesamum indicum L.) was studied at three root temperature regimes (25/25, 20/10 and 15/15°C day/night) factorially combined with three NO 3 ‐: NH 4 + ratios (mM ratios, 10:0, 8:2, or 6:4), as a source of nitrogen (N), in the irrigation solution. The air temperature was kept constant at 30°C. Transpiration, nutrient composition, and level of root‐born cytokinins and gibberellins in the xylem exudate were monitored. The two low root temperature regimes, 15/15 and 20/10°C, restricted the growth of sesame, reduced transpiration and increased the accumulation of soluble carbohydrates in the shoot and in the roots compared to the 25/25°C regime. The NO 3:NH 4 + ratios had no effect on growth. Nutrient contents in the shoot at low root temperatures, particularly K +, NO 3 ‐, and H 2PO 4 ‐ were decreased markedly, but Na + increased relative to it's content in the 25/25°C regime. Increasing NH 4 + proportion in the irrigation solution raised total N concentration in the plant tissues at all root temperatures. The amounts of cytokinins and gibberellins in the xylem exudate decreased at the low root temperature regimes relative to the 25/25°C regime. Low root temperature reduced xylem transport of nutrients and root born‐phytohormones, most probably because of reduced water flow through the plant relative to the 25/25°C regime. 相似文献
4.
Abstract In a pot experiment, the effects of NO 3‐N and NH 4‐N fertilizer were examined on the pH of the bulk soil and rhizosphere, and on the growth and nutrient uptake of 18–35‐d old bean plants ( Phaseolus vulgaris L.) supplied with KH 2PO 4 or rock phosphate (Hyperphos). Prior to sowing, the soil was incubated for 16 d to ensure complete nitrification of NH 4‐N which decreased bulk soil pH from 6.8 to 5.5. In other pots, a nitrification inhibitor, N‐Serve, was added together with the ammonium fertilizer and after 18 d growth, the pH of the bulk soil was 6.6 while the pH of the rhizosphere decreased to 4.5. Shoot and root dry matter yield was significally greater for plants supplied with KH 2PO 4 and fertilized with NH 4‐N compared with NO 3‐N. This increased growth by NH 4‐N fed plants was presumably due to a increased nutrient availability caused by the acidification of the bulk soil. Shoot concentrations of ? and micronutrients, such as Fe, Mn, Zn, and Cu, were higher for plants supplied with NH 4‐N, and more strikingly were higher for plats supplied with NH 4‐N+N‐Serve when expressed on a root length basis. In this latter case, the increased nutrient acquisition by plants could only be due to acidification of the rhizopshere. The inhibitory effect of NH 4‐N+N‐Serve, particularly on root growth, was not caused by NH 4+ toxicity, but was due to a direct effect of N‐Serve as shown by growth comparisons with another nitrification inhibitor, dicyanodiamide (DCD). 相似文献
5.
Oilseed rape ( Brassica napus L.) response to root temperature regimes (20/20, 16/8 and 12/12°C day/night) at constant 20°C air temperature was studied. At each regime, three NO 3 ‐:NH 4 + ratios (10:0, 8:2, or 6:4), at constant 10 mM N, in the irrigation solution were tested. Plant growth, transpiration, ionic composition and level of cytokinins and gibberellins in the xylem exudate were monitored. The two low root temperature regimes, 12/12 and 16/8°C, reduced rape shoot growth by 28 and 22%, and increased the accumulation of soluble carbohydrates by 42 and 26% in the roots, respectively, as compared to the 20/20°C regime. Low root temperatures reduced plants transpiration. The NO 3 ‐:NH 4 + ratios had no effect on rape growth. At low root temperatures NO 3 ‐contents increased in the shoot and decreased in the roots. The sum of cations and that of anions at 12/12 and 16/8°C root temperatures decreased significantly as compared to 20/20°C. The presence of NH 4 + in the irrigation solution decreased the concentrations of Ca 2+ and Mg 2+ in the shoots and roots and increased that of Cl ‐ in the shoots and of H 2PO 4 ‐ in the roots at all root temperatures. Cytokinins and gibberellins contents in the xylem exúdate decreased at the low root temperature regimes. Low root temperature reduced total upward transport of the mineral nutrients and phytohormones, most probably because of reduced water flow through the plant. 相似文献
6.
Poinsettia cultivars Supjibi and Freedom were grown in eight hydroponic solutions to develop a baseline solution for further nutritional studies. Four solutions contained nitrogen (N) from Ca(NO 3) 2‐4H 2O and KNO 3 (denoted as ‐NH 4) and four contained Ca(NO 3) 2‐4H 2O, KNO 3, nitric acid, and NH 4NO 3 as the N sources (denoted as +NH 4). The four ‐NH 4 and +NH 4 solutions were further divided by an IX or 2X rate of micronutrients [boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn)] (denoted as IX or 2X). A factorial of these four solutions at 2 concentrations (100 mg L 1 of N and potassium (K) and 15 mg L 1 phosphorus (P), or 300 mg L 1 of N and K and 46 mg L ‐1 P) was studied. Greater leaf and stem dry weight for both ‘Supjibi’ and ‘Freedom’ was observed in plants grown with the +NH 4 solutions, with a larger increase occurring with’ Supjibi’. Leaf NH 4‐N content for both cultivars was higher for both the 100 and 300 mg L ‐1 N and K fertilization rates when NH 4‐N was included. The leaf K content was highest for the plants grown with the +NH/2X solution for ‘Supjibi’, for both fertilization rates, and leaf K content increased as the K application rate increased. Results indicate that for nutritional studies with poinsettias, hydroponic solutions should include between 12.5% to 33% of the N in the NH 4 form, a calcium magnesium (Ca:Mg) ratio of 2:1, and a micronutrient concentration of (mg I/ 1) 0.5, 0.02, 6.6, 0.5, 0.1, and 0.05, respectively, for B, Cu, Fe, Mn, Mo, and Zn, for adequate plant growth. 相似文献
7.
Abstract Experiments were conducted using different NO 3 –/NH 4 + ratios to determine the effects of these sources of N on mineral element uptake by sorghum [ Sorghum bicolor (L.) Moench] plants grown in nutrient solution. The NO 3 –/NH 4 + ratios in nutrient solution were 200/0, 195/5, 190/10, and 160/40 mg N L –1. Nutrient solutions were sampled daily and plants harvested every other day during the 12‐day treatment period. Moderately severe Fe deficiencies were observed on leaves of plants grown with 200/0 NO 3 –/NH 4 + solutions, but not on the leaves of plants grown with the other NO 3 –/NH 4 + ratios. As plants aged, less Fe, Mn, and Cu were translocated from the roots to leaves and leaf/root ratios of these elements decreased dramatically in plants grown with 200/0 NO 3 –/NH 4 + solutions. Extensive amounts of Fe, Mn, and Cu accumulated in or on the roots of plants grown with 200/0 NO 3 –/NH 4 + solutions. Manganese and Cu may have interacted strongly with Fe to inhibit Fe translocation to leaves and to induce Fe deficiency. As the proportion of NH 4 + in solution increased, K, Ca, Mg, Mn, and Zn concentrations decreased in the leaves, and Ca, Mg, Mn, and Cu concentrations decreased in roots. Potassium and Zn tended to increase in roots as NH 4 + in solution increased. 相似文献
8.
Abstract Inhibition of nitrification in soil results in a decreased ratio of nitrate‐nitrogen (NO 3‐N) to ammonium‐nitrogen (NH 4‐N). If the conditions for NO 3‐N loss by leaching or denitrification exist, nitrification inhibitors should increase concentrations of total inorganic soil nitrogen (N) (TISN) (NH 4‐N + NO 3‐N). This can then result in plants taking up more N and developing more crop yield or biomass. This study examined whether inhibition of nitrification by dicyandiamide (DCD) would result in increased concentrations of TISN under field conditions. The effects of DCD on soil N were evaluated in hyperthermic sandy soils planted to potato ( Solanum tuberosum L., cv. Atlantic). Treatments were factorial combinations of N as ammonium nitrate (NH 4NO 3) at 67, 134, and 202 kg N ha ‐1 and DCD at 0, 5.6, and 11.2 kg DCD ha ‐1. Soil NH 4‐N, NO 3‐N, and TISN concentrations were determined for up to five potato growth stages at two locations for two years for a total of 16 determinations (cases), i.e., four were not determined. The N form ratio [NO 3‐N/(NH 4‐N + NO 3‐N] x 100 was decreased in 10 of 16 cases, indicating that nitrification was inhibited by DCD. With two of these 10 cases, TISN concentration increased, but with four others, TISN concentration decreased with at least one N rate. With four of these 10 cases, inhibition of nitrification had no effect on TISN concentration. Under the conditions of these field studies, DCD inhibited nitrification more often than not. Inhibition of nitrification was, however, more likely to reduce TISN concentration than to increase it. This may have been due to DCD effects on immobization of applied NH 4‐N. 相似文献
9.
ABSTRACT Impatiens ( Impatiens wallerana Hook. f.) is the most important annual bedding plant in the United States, based on wholesale dollar volume. Production of high-quality plants requires optimization of the nutrition regimen during growth, especially the total nitrogen (N) concentration and the ratio of N sources. The objective was to determine the N concentration and the nitrate (NO 3 ??N):ammonium (NH 4 +?N) ratio of N source that optimized bedding-plant impatiens growth and flower development. Four N concentrations (3.5, 7, 10.5, and 14 mmol N · L ?1) were used in factorial combination with four ratios of NO 3 ??N:NH 4 +?N (4:0, 3:1, 1:1, and 1:3). Application of treatments was made for 30 d. Then for 10 d only deionized water was applied to reduce salt buildup. Substrate pH was lowest (4.9) with the NH 4 +?N source and electrical conductivity (EC) highest, but never > 2.4 dS m ?1. Nitrogen concentration and N source displayed an interaction for most growth parameters. Shoot fresh and dry weights and flower bud number were maximized at the 1:3 NO 3 ??N:NH 4 +?N ratio with a N concentration of 10.5 mmol L ?1. However, plant diameter, leaf number, and leaf chlorophyll content responded quadratically to N form ratio, with the 1:1 ratio optimum at a concentration of 10.5 mmol N· L ?1. 相似文献
10.
Abstract This study was designed to explore nitrogen (N) nutrition in bearberry plants ( Arctostaphylos uva‐ursi L.) using a hydroponic culture system. Two experiments were performed in which the total N concentration (34, 52, and 73 mg L ?1) and N‐NO 3 ?:N‐NH 4 + ratio (50/50, 60/40, and 70/30 in %) in the nutrient solution were varied and effects on nutrient uptake [N, phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] and foliar composition determined. Highest‐quality plants were yielded using a N level of 73 mg L ?1 and a N‐NO 3 ?:N‐NH 4 + ratio of 50/50. Standard nutrient values for foliar tissue were obtained for bearberry plants growing in these hydroponic cultures for their use as preliminary norms in the diagnosis and recommendation integrated system (DRIS). In a subsequent complementary experiment, these norms were used in the DRIS procedure and applied to plants growing in solutions of varying K concentrations. It was found that the DRIS norms established in the hydroponic experiments were able to account for changes in nutrient limiting factors produced in response to the varying K concentrations in the nutrient solution. The results obtained will be useful for the nutritional diagnosis of bearberry plants. 相似文献
11.
Plant nitrogen (N) uptake, growth, and N use efficiency may be affected by N form (NO 3 ‐or NH 4 +) available to the root. The objectives of this study were to determine the effect of mixed N form on dry matter production and partitioning, N uptake, and biomass N use efficiency defined as total dry matter produced per unit plant N (NUE 1) in U.S. and tropical grain sorghums [Sorghum bicolor (L.) Moench]. The U.S. derived genotype CK 60 and three tropical genotypes, Malisor‐7, M 35–1, and S 34, were evaluated in a greenhouse trial using three nutrient solutions differing in their NO 3 ‐/NH 4 + ratio (100/0, 75/25, 50/50). Shoot and root biomass, N accumulation, and NUE, were determined at 10‐leaf and boot stages. Averaged over all genotypes, shoot and root biomass decreased when NH 4 + concentration was increased in the solution. Shoot biomass was reduced by 11% for 75/25 and 26% for 50/50 ratios, as compared to 100/0 NO 3 ‐/NH 4 +. Similarly, root biomass reduction was about 34% and 45% for the same ratios, respectively. Increasing NH 4 + concentration also altered biomass partitioning between shoot and root as indicated by decreasing root/shoot ratio. Total plant N content and NUE 1 were also reduced by mixed N source. Marked genotypic variability was found for tolerance to higher rates of NH 4 +. The tropical line M 35–1 was well adapted to either NO 3 ‐ as a sole source, or to an N source containing high amounts of NH 4 +. Such a characteristic may exist in some exotic lines and may be used to improve genotypes which do not do well in excessively wet soil conditions where N uptake can be reduced. 相似文献
12.
‘Helleri’ holly (Ilex crenata Thunb. ‘Helleri') plants were grown in solution culture at aluminum (Al) concentrations of 0, 6, 12, 24, and 48 mg.L ‐1 for 116 days. Aluminum did not affect root or crown index, stem length growth, plant dry weight, or leaf area. Aluminum treatments significantly increased Al uptake and reduced nutrient uptake of magnesium (Mg), calcium (Ca), zinc (Zn), and copper (Cu) on some sampling dates. Iron (Fe) and manganese (Mn) uptake decreased on most sampling dates but increased on some with Al treatments. Potassium (K), phosphorus (P), and boron (B) uptake were significantly affected by Al, decreasing and increasing at different sampling dates. Although plants preferentially took up ammonium‐nitrogen (NH 4 +‐N) in all treatments (including 0 Al controls), neither NH 4 +‐N nor nitrate‐nitrogen (NO 3 ‐N) uptake were affected by Al. Tissue concentrations of P, K, B, Zn, and Al increased with Al treatment; whereas tissue Ca, Mg, and Cu concentrations decreased with increasing Al. Iron and Mn tissue concentrations exhibited increases and decreases in different tissues. Results indicated that ‘Helleri’ holly was tolerant of high concentrations of Al. 相似文献
13.
Zucchini squash ( Cucurbita pepo L. cv. Green Magic) plants were grown hydroponically with nitrate (NO 3):ammonium (NH 4) ratio of 3:1 until the onset of flowering when the plants were assigned to four NO 3:NH 4 ratio (1:0, 1:1, 1:3, or 3:1) treatments. Changing the original nitrogen (N) form ratio significantly affected plant growth, fruit yield, nutrient element, and water uptake. Growth of plants was better when NO 3‐N (1:0) was the sole form of N than when NH 4‐N was part of the N treatment. Fruit yields for plants fertilized with 1:0 or 1:3 N‐form ratio were double those of plants grown continuously with 3:1 N ratio. The largest leaf area and plant water use were obtained with 1:0 N ratio treatment Total uptake of calcium (Ca), magnesium (Mg), and potassium (K) decreased with increasing NH 4‐N proportion in the nutrient solution which suggest NH 4‐N was competing with these cations for uptake. The results also demonstrated that growers may increase fruit yield by using a predominantly NO 3‐N source fertilizer through the vegetative growth stage and by shifting the NO 3:NH 4 ratio during the reproductive phase. 相似文献
14.
Abstract The primary nitrogen forms utilized by plants are ammonium and nitrate. Although the importance of nutrients other than nitrogen for proper turfgrass growth is well established, the amounts of these nutrients in the plant tissue in relation to the use of different N‐forms has not been clearly documented. This study was conducted under greenhouse conditions to determine the effect of N‐form and cutting regime on growth, macronutrient, and micronutrient content of creeping bentgrass (Agrostis palustris Huds. ‘Penncross'). Treatments consisted of 100% NO3 ? (calcium nitrate), 100% NH 4 + (ammonium sulfate), and a 50:50 ratio of NH 4 +:NO 3 ?. Half the turfgrass plants were maintained at a height of 1 cm (cut), while the other half of the plants were not cut until the end of the study (uncut). The uncut 50:50 treatment yielded the highest shoot, verdure, and total plant dry matter, while the uncut NO 3 ? treatment produced the highest root dry matter. The uncut NH 4 + treatment yielded the least shoot, root, and total plant dry matter. Plants of the uncut NO 3 ? treatment had greater accumulation of macronutrients in the shoot and root tissue compared to plants of the NH 4 + treatment. The uncut NO 3 ? and 50:50 treatments had higher total accumulation of micronutrients compared to the uncut NH 4 +‐treated plants. The cut NO 3 ? treatment resulted in the highest macronutrient and micronutrient contents in the root tissue in comparison to other cut treatments. The cut treatments had the highest percentage accumulation of nutrients in the verdure tissue, while the uncut treatments had the highest percentage accumulation of nutrients in the shoot tissue. 相似文献
15.
Inorganic nitrogen (N) in soils is a primary component of soil‐plant N buffering. This study was conducted to determine if non‐exchangeable ammonium‐nitrogen (NH 4‐N) could serve as an index of potentially mineralizable organic N which is an important sink in N buffering. Four long‐term winter wheat ( Triticum aestivum L.) experiments that had received annual fertilizer N at 0 to 272 kg N ha ‐1 were used. Soils from these experiments were extracted by four 10 mL portions of 2M potassium chloride (KC1) at room temperature followed by extraction with 20 mL of 2M hot KC1. Extraction at 100°C for four hours using 3 g soil and 20 mL 2M KC1 was found to be the most effective. Hot KC1‐extractable NH 4‐N minus room temperature KCl‐extractable NH 4‐N was considered non‐exchangeable NH 4‐N. Non‐exchangeable NH 4‐N was correlated with the long‐term N rates, and believed to be a reliable index of potentially mineralizable organic N. The relationship was linear for NH 4‐N where the lowest N rate had the lowest extractable N. The mean non‐exchangeable NH 4‐N concentration ranged from 8.42 to 16.34 mg kg ‐1; whereas, nitrate‐nitrogen (NO 3‐N) ranged from 0.07 to 1.87 mg kg 1. Total inorganic N extracted was similar to that mineralized in a 42‐day aerobic water saturated incubation. In addition, using a linear‐plateau model, extractable NH 4‐N was highly correlated with long‐term average yield (R 2=0.92). For the soils evaluated, this method provided a rapid measure of potentially mineralizable N. 相似文献
16.
Pearl millet [Pennisetum glaucum (L.) R. Br.] is a potentially high‐yielding grain crop for the Southern Coastal Plain region of the USA. Information on the growth and N nutrition of pearl millet is limited; therefore, this study was initiated with the objective of studying pearl millet growth, N content, N uptake patterns and N‐form preference. Plants were grown in solution culture using a modified Hoagland's solution. Solutions were changed weekly and transpirational losses replaced daily. The N‐form ratios were 1:0, 3:1, 1:1, 1:3 and 0:1 NH 4 + to NO 3 ‐ Uptake was determined by difference between the initial and final solutions. Nitrate and NH 4 + uptake patterns were different from each other and were influenced by the ratio of NH 4 + to NO 3 ‐. After the plants had been transferred to the solutions, ammonium was preferred for the first two weeks, with NO 3 ‐ preferred thereafter. Nitrate uptake was highest during the grain filling period. Plant growth as measured by leaf, stem, root, and seed weight, plant height, average seed weight, and head length was generally reduced as NH 4 + increased. The largest reduction was observed between the 3:1 and 1:0 ratios. Ammonium nutrition had an overall negative effect on pearl millet growth. Ammonium fertilization of pearl millet under conditions that increase absorption of NH 4 + over NO 3 ‐ may have a negative effect on pearl millet growth and development. 相似文献
17.
Abstract Nitrite (NO 2 ?‐N) toxicity symptoms have been observed on lettuce ( Lactuca sativa) at various locations in California. The objective was to evaluate the symptoms of ammonium (NH 4 +‐N) and nitrite (NO 2 ?‐N) toxicity on Sundevil iceberg lettuce and Paragon romaine lettuce and to determine lettuce growth and biomass production under different levels of NO 2 ?‐N. Hydroponic studies under greenhouse conditions were conducted using nutrient solutions containing nitrate (NO 3 ?‐N) and two other forms of nitrogen (NO 2 ?‐N and NH 4 +‐N) applied at a constant concentration (50 mg NL ?1) or using different NO 2 ?‐N levels (0, 5, 10, 20, 30, and 40 mg N L ?1) and a constant NO 3 ?‐N level (30 mg N L ?1). Crown discoloration (brownish color) was observed for lettuce grown in both NO 2 ?‐N and NH 4 +‐N solutions approximately 3 weeks after transplanting into the hydroponic systems. Lettuce grown in NO 3 ?‐N solution produced larger biomass and greater number of leaves per plant than lettuce grown in NO 2 ?‐N or NH 4 +‐N solutions. Increasing the concentration of NO 2 ?‐N suppressed plant height, fresh and dry biomass yield, and number of leaves and increased the root vascular discoloration. Lettuce growth was reduced more than 50% at NO 2 ?‐N concentrations greater than 30 mg N L ?1. Even at 5 mg NO 2 ?‐N L ?1, growth was reduced 14 and 24% for romaine and iceberg lettuce, respectively, relative to that obtained in nitrate solution. Although concentrations between 5 and 40 mg NO 2 ?‐N L ?1 reduced dry biomass similarly for both lettuce types, toxicity symptoms were more severe in iceberg lettuce than in romaine. 相似文献
18.
Abstract Seedlings of four maize hybrids were grown hydroponically to investigate the impact of different N sources (Ca(NO 3) 2, (NH 4) 2SO 4 and a 1:1 mixture of both) on (i) production and partitioning of root and shoot dry matter, (ii) concentration of soluble carbohydrates in roots and shoots and their partitioning to these plant parts, (iii) concentration of starch in the shoot, and (iv) N uptake. During the main phase of the experiments (duration 14d), the plants were grown in a greenhouse at 25/22°C day/night temperatures and a photoperiod of 16h. Nitrogen was supplied at three concentrations (2.8, 28, and 280 ppm). The root‐zone pH was 6.5. Under the lowest N supply, the N sources produced similar root and shoot dry matters. At the highest N level (280 ppm), NO 3‐fed plants were superior. In contrast, the mixture of NH 4 and NO 3 ? was optimum at 28 ppm. More or less pronounced N form by N concentration interactions were also found in the concentration and distribution of soluble carbohydrates and in all remaing traits. There were almost statistically significant cultivar by N form interactions in shoot dry matter (P = 0.07) and total dry matter (P = 0.06), indicating the existence of considerable genotypic variation in sensivity to NH 4‐N. 相似文献
19.
Abstract This trial was carried out to establish an appropriate nutrient solution for Aglaonema commutatum and to investigate the nutritional effects generated by modifications in the solution. Six treatments were tested: control (T 0; pH 6.5, E.C. 1.5 dS m ?1, 6 mmol L ?1 NO 3 ?‐N, and 6 mmol L ?1 K +); high nitrogen (N) level (T 1; 9 mmol L ?1 6:3 NO 3 ?–NH 4 +); N form (T 2; 6 mmol L ?1 N‐NH 4 +); high K + level (T 3; 12 mmol L ?1 K +); high electrical conductivity (T 4; E.C. 4 dS m ?1, 25 mmol L ?1 NaCl), and basic pH (T 5; pH 8). At the end of the cultivation, leaf, shoot, and root dry weights and elemental concentrations were determined. Nutrient contents and total plant uptake were calculated from the dry weights and nutrient concentrations. Plant K + uptake increased with application of K + or basic nutrient solution. The uptake and transport of calcium (Ca) were enhanced by the use of NO 3 ?‐N and inhibited by the presence of other cations in the medium (NH 4 +, K +, Na +) and by basic pH. Magnesium (Mg) uptake increased with NO 3 ?‐N application and with pH. Sodium (Na) uptake was the highest in the saline treatment (T 4), followed by the basic pH treatment. Sodium accumulation was detected in the roots (natrophobic plant), where the plant generated a physiological barrier to avoid damage. Dry weight did not differ significantly (p<0.05) among treatments except in the NaCl treatment. These results may help in the formulation of nutrient solutions that take into account the ionic composition of irrigation water and the physiological requirements of plants. 相似文献
20.
Abstract Plant growth in saline soils is regulated by the availability of nitrogen (N). High soil nitrate (NO 3)‐N can lead to poor water quality. Many workers think that NO 3‐N as a source for N can contribute to better plant growth in saline soils. The purpose of this work was to determine the necessity of NO 3‐N and the ratio of NO 3/ammonium (NH 4) in the N fertilizer which gives higher productivity of the biomass yield of corn. Corn ( Zea mays L.) plants (Var. LG11) were grown under saline soil conditions (8.5 dS m ‐1), soils taken from the Euphrates valley (ACSAO Research Station) at Deir‐Ez‐Zor, east of Syria, from the surface layer of soil (0–25 cm). Five levels of N were applied in two forms, ammonium sulfate [ 15(NH 4) 2SO 4] with enrichment (1.5% a) as the NH 4‐N form and calcium nitrate [Ca(NO 3) 2] as the NO 3‐N form, besides fixed amounts of phosphorus (P) and potassium (K) for all N treatments. The corn plants were harvested at the flowering stage (56 days old), oven dried, weighed, and analyzed for total N and 15N recovery. The results indicated that the dry matter weight for treatments which received a combination of NH 4‐N and NO 3‐N gave higher dry matter yield than a single treatment of one source of N. But, NO 3‐N was more effective in improving yield than NH 4‐N. Nitrogen recoveries on the basis of added and absorbed N derived from fertilizer were significantly more affected by NO 3‐N than NH 4‐N. 相似文献
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