INFLUENCE OF SALINITY AND AMMONIUM: NITRATE RATIO ON GROWTH,PHOTOSYNTHESIS, FATTY ACID AND THE ACTIVITY OF ANTIOXIDATIVE ENZYMES IN CANOLA

The effects of sodium chloride (NaCl) salinity (0 and 200 mM) and ammonium (NH₄):nitrate (NO₃) ratios (100:0, 25:75, 50:50, and 75:25) on growth, photosynthesis, fatty acids and the activity of antioxidative enzymes were investigated in canola plants. Leaf area and fresh and dry weights of leaves were significantly reduced by the salinity. The reduction in vegetative characteristics varied in both salinized and unsalinized plants according to the NH₄:NO₃ ratios so that the lowest reduction was observed with the 50:50 (NH₄:NO₃) ratio. Increased NH₄ up to 50 percent (50:50) of total N, promotes the yield at both salinized and unsalinized plants. In both salinized and unsalinized plants, the increased NH₄ and NO₃ ratio in the nutrient solution reduced the photosynthetic (Pn) rate and stomatal conductance; however, the reduction in Pn rate was severely impaired at a higher ratio of NH₄ in the nutrient solution. In both salinized and unsalinized plants, the 75:25 ratio had the lowest potassium (K) and sodium (Na) content; however, the K/Na ratio was the highest in 50:50 ratio. An increase of NH₄ in the solution led to a significant increase in NH₄ content in both salinized and unsalinized plants. Salinity increased NH₄ content so that the salinized plant had nearly twice as high NH₄ content in the leaves. The activity of nitrate reductase was increased by increasing NH₄ from 0 to 50% and then reduced at a higher ratio of NH₄ in the solution. The activities of antioxidative enzymes increased in salinized plants regardless of the NH₄:NO₃ ratios. In salinized plants, the activities of superoxide dismutase and catalase enzymes were increased by 44.4 % and 97.5%, respectively. Within salinized and unsalinized treatments, the highest activities of all antioxidant were observed in 75:25 ratio, while they remained unchanged for all NH₄:NO₃ ratios. The increased NH₄ content in the solution increased the oil content and the maximum oil content in both salinized and unsalinized plant was obtained in both 50:50 and 75:25 ratios. The percentage of oleic acid was affected by both salinity and NH₄:NO₃ ratios. The ratios of NH₄:NO₃ had no effect on the protein content; however, salinity reduced the protein content by 20%.     

Influence of Pre-Plant Micronutrient Mixes and Ammonium to Nitrate Ratios in Fertilizer Solution on Growth and Micronutrient Contents of Marigold in Plug Culture

ABSTRACT

The purpose of this work was to determine the effects of pre-plant micronutrient mixes and various ammonium/nitrate (NH₄ ⁺/NO₃ ^?) ratios in a fertilizer solution on growth and the nutrient uptake of French marigold ‘Orange Boy’ in a plug culture. Two kinds of granular glass frits containing six micronutrients were produced and incorporated into peatmoss+vermiculite (1:1, v/v) substrate at a rate of 0.3 g · L^{? 1}. The five NH₄ ⁺/NO₃ ^? ratios in fertilizer solution were 0/100, 25/75, 50/50, 75/25, and 100/0, each giving a total nitrogen (N) supply of 80, 100, and 120 mg · L^{? 1}in the root substrate during stages 2, 3, and 4, respectively. The plants produced a significantly higher fresh and dry matter yield at 35 days after sowing when grown in 25/75 N nutrition in micronutrient fertilizer 1 (MF1) and 50/50 in micronutrient fertilizer 2 (MF2) than in the other NH₄ ⁺/NO₃ ^? ratios tested. Treatments of the highest accumulation of iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B) in plants were 25/75, 50/50, 50/50, 25/75 and 50/50 in MF1 and 50/50, 25/75, 50/50, 50/50, 50/50 in MF2, respectively. The trends in accumulations of Fe, Mn, Zn, Cu, and B in plants were quadratic (Q), linear (L) and Q, L and Q, L and Q, and Q, respectively, in MF1. Those in MF2 were Q, Q, Q, L and Q, and Q, respectively.     

Nitrogen partitioning in greenhouse‐grown broccoli in response to varying NH+ 4:NO− 3 ratios

Abstract

Broccoli (Brassica oleracea var. italica) plants were grown in the greenhouse and supplied continuously with 18 mM N in the following NH⁺ ₄:NO^? ₃ ratios: 100:0, 75:25, 50:50, 25:75, 0:100. At commercial maturity, the plant characteristics and partitioning of nitrogen in xylem and phloem saps and in plant tissue were determined. Plants fed solely with NH⁺ ₄ were stunted, exhibited signs of marginal necrosis on the lower leaves, and accumulated NH⁺ ₄ in the foliage. The maximum yield and shortest harvest time, together with minimal NO^? ₃ and NH⁺ ₄ accumulation were found at a ratio of 75:25. Ammonium concentrations in xylem sap decreased linearly with decreasing NH⁺ ₄ portion in the nutrient solution, whereas the NO^? ₃ concentrations reached a maximum when NO^? ₃ constituted 50% of the N supply. The glutamate family dominated the amino acid composition of both xylem and phloem saps, but did not vary much with NH⁺ ₄:NO^? ₃ ratio. It is suggested that the NH⁺ ₄ concentration in xylem sap may be used to assess NH⁺ ₄ vs NO^? ₃ utilization by broccoli grown under field conditions.     

不同铵硝配比对弱光下白菜氮素吸收及相关酶的影响

以黑色遮阳网覆盖模仿弱光环境, 使光照强度为自然光的20%左右, 以自然光照为对照, 采用精确控制水培溶液氮素营养, 研究NH₄⁺-N/NO₃^--N 比例分别为0/100、25/75、50/50、75/25、100/0 对弱光下白菜氮代谢及硝酸还原酶和谷氨酰胺合成酶活性的影响。结果表明, 弱光下, 白菜的鲜重及叶片总氮量以NH₄⁺-N/NO₃^--N 比为25/75 时最大, NH₄⁺-N/NO₃^--N 比为100/0 时最低。随弱光处理的进行, 白菜叶片中硝酸还原酶活性及谷氨酰胺合成酶活性均呈下降趋势, 但NH₄⁺-N/NO₃^--N 比为25/75 时, 可维持叶片内较高的硝酸还原酶活性及谷氨酰胺合成酶活性。试验表明, NH₄⁺-N/NO₃^--N 比25/75 是白菜在弱光下生长的较适宜氮素形态配比。     

Effect of Ammonium:Nitrate Ratios in the Response of Strawberry to Alkalinity in Hydroponics

Strawberry (Fragaria ananasa) plants were grown in hydroponics in a greenhouse, where the supply of different ammonium (NH₄⁺): nitrate (NO₃^?) ratios, was investigated to reduce the negative effect of alkalinity in nutrient solutions. The experiment was arranged in factorial combination with two factors, NH₄⁺:NO₃^? ratios (0%:100%, 25%:75%, 50%:50%, 75%:25%, and 100%:0%) and bicarbonate (0, 25, 50, and 75 mM; NaHCO₃). Plants treated with increasing bicarbonate concentrations exhibited significantly inhibited growth. In plants treated with NH₄⁺ and NO₃^? simultaneously, there was a counteraction of the bicarbonate-induced growth suppression. Sole NO₃^? application in the presence of high bicarbonate resulted in poor growth and plant death due to high alkalinity. The adverse effect of alkalinity on SPAD values and maximal quantum yield of PSII photochemistry (F_v/F_m) alleviated with increasing proportion of NH₄⁺ in nutrient solutions. The results showed that fruit numbers and yield of strawberry increased with elevation of NH₄⁺ in nutrient solutions.     

Effects of Nitrogen Source on Growth and Development of Strawberry Plants

ABSTRACT

An experiment was conducted to study the effects of nitrate (NO₃ ^?) and ammonium (NH₄ ⁺) ratios in nutrient solutions on the growth and production of fruits, runners, and daughter plants of strawberry Fragaria x ananassa Duch., grown in a hydroponic system. Five treatments were applied, consisting of different proportions of NH₄ ⁺ and NO₃ ^? in the nutrient solution. The NH₄ ⁺:NO₃ ^? ratios were: T0 = 0:4, T1 = 1:3, T2 = 2:2, T3 = 3:1, and T4 = 4:0, at a constant nitrogen (N) concentration of 4 mol m^?3. Growth and morphogenesis were characterized by monitoring leaf-area increase, number of flowers and fruits per plant, and number of daughter plants of first and second generations. Nitrogen and carbon (C) content were measured at the end of the experiment in the organs of both mother and daughter plants. None of the variables related to the growth of the mother plant was affected by the treatments. However, the number of fruits increased with the proportion of NH₄ ⁺ in the nutrient solution. The number of daughter plants produced was affected only at high NH₄ ⁺ proportions, and their size (dry matter per daughter plant) and fertility (number of second-generation plants per first-generation plants) were reduced. The N or C content of the plants was not significantly affected by the treatments, but the C/N ratio in the crowns of mother plants was higher in treatments with 25% and 50% NH₄ ⁺ in the nutrient solution.     

Effect of nitrogen form during the flowering period on zucchini squash growth and nutrient element uptake

Zucchini squash (Cucurbita pepo L. cv. Green Magic) plants were grown hydroponically with nitrate (NO₃):ammonium (NH₄) ratio of 3:1 until the onset of flowering when the plants were assigned to four NO₃:NH₄ 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 NO₃‐N (1:0) was the sole form of N than when NH₄‐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 NH₄‐N proportion in the nutrient solution which suggest NH₄‐N was competing with these cations for uptake. The results also demonstrated that growers may increase fruit yield by using a predominantly NO₃‐N source fertilizer through the vegetative growth stage and by shifting the NO₃:NH₄ ratio during the reproductive phase.     

Tomato growth,nitrogen fraction and mineral composition in response to nitrate and ammonium foliar sprays 1

Tomato plants were grown in sand culture with NO₃ or NH₄ N at two levels of light. Foliar sprays at three levels of N as well as combinations of foliar and root feeding were used.

Shade increased NH₄ toxicity in plants sprayed with NH₄ but decreased the toxicity in plants receiving NH₄ through the roots. NH₄‐N greatly reduced growth and cation uptake when supplied through the roots but not with foliar application. Plants sprayed with NH₄ showed better growth, higher K, Ca, and Mg content and lower free NH₄ in shoot, compared to plants receiving NH₄ through the roots.

The overall free amino acid contents of shoots was higher for NH₄‐fed plants regardless of how the N was applied. Plants sprayed with NH₄ incorporated a greater amount of N into insoluble compounds compared with NO₃ nutrition. The N uptake per unit of leaf area was higher for plants grown under full sun light whereas N content was higher for plants grown under hade. N content in tissue increased with N concentration in foliar spray, although plants supplied with N through the roots had higher levels of free amino acids and total nitrogen.     

Ammonium reduces growth,fruit yield and fruit quality of watermelon

Watermelon (Citrullus lunatus Thunb.) plants cv ‘Sugar Baby’ were grown hydroponically in a greenhouse under NO₃:NH₄ ratios of 3:1, 1:1, and 1:3. Plants receiving the high ammonium treatment expressed symptoms of NH4‐toxicity and declined rapidly after bloom. Reducing NO₃:NH₄ from 3:1 to 1:1 significantly reduced growth, water use, fruit yield, flesh soluble solids and uptake of NO₃, NH₄, K, Ca and Mg.     

The influence of the form of nitrogen nutrition on uptake and distribution of cadmium in lettuce varieties

Four lettuce (Lactuca saliva L.) varieties ('Benita’, ‘Wendy’, ‘Mirena’, and ‘Jacky') were grown for 43 days in a pH‐controlled complete nutrient solution without cadmium (Cd) or with either 0.01 or 0.03 mg Cd/1 and with NH₄ or NO₃ as the form of nitrogen nutrition. Cadmium did not affect dry matter yield. ‘Wendy’ had a significantly higher total dry matter production when grown on NO₃ compared to NH₄, whereas growth of ‘Mirena’ was best on NH₄ (P<0.05). Dry weights of ‘Benita’ and ‘Jacky’ were not affected by the N source. Cadmium concentrations in shoots (and roots) of plants grown on NH₄ were significantly higher than in plants grown on NO₃. The Zn concentrations in the shoots were also enhanced. The distribution of Cd in the lettuce varieties was independent of the form of N nutrition. It is concluded that the N source directly affects the amount of Cd taken up, without influencing the Cd distribution.     

Nitrate/ammonium ratio effects on nutrient solution pH,dry matter yield,and nitrogen uptake of sorghum 1

Abstract

Sorghum [Sorghum bicolor (L.) Moench] seedlings were grown in nutrient solutions in a growth chamber to investigate the effects of different ratios of NO₃ ^– and NH₄ ⁺ on nutrient solution pH, dry matter yield, and N uptake. Nutrient solutions and plant tissues were assayed throughout the time plants grew in the nutrient solutions.

Nutrient solution pH depended on source of N. The pH rose to near 8 with NO₃ ^– as the sole source of N and decreased to near or below 4 with NH₄ ⁺ added to the solutions. Upon depletion of NH₄ ⁺ from solution, pH values rose abruptly to near 8 and remained near this value throughout the duration of the experiments. Dry matter yield was generally higher for plants grown with some NH₄ ⁺ compared to plants grown with NO₃ ^– alone. Nitrogen uptake was generally higher in plants grown with the higher proportions of NH₄ ⁺. Nitrogen concentrations remained unchanged with plant age as NO₃ ^–/ NH₄ ⁺ ratio varied. For solutions low in NH₄ ⁺, N concentrations in roots increased with plant age. Severe Fe deficiency appeared in plants when solution pH reached and remained above 7.     

Nitrate and ammonium nutrition in chicory and rocket salad plants

To evaluate chicory (Cichorium intybus L.) and rocket salad [Eruca vesicaria (L.) Cav.subsp. sativa (Mill.)] capability to use ammonium‐nitrogen (NH₄‐N) even in the absence of nitrate‐nitrogen (NO₃‐N) in the nutrient solution, and the chances they offer to reduce leaf NO₃ content, cultivated rocket and two cultivars of chicory ('Frastagliata’, whose edible parts are leaves and stems, and ‘Clio’, a leaf hybrid) were hydroponically grown in a growth chamber. Three nutrient solutions with the same nitrogen (N) level (4 mM) but a different NH₄‐N:NO₃‐N (NH₄:NO₃) ratio (100:0, 50:50, and 0:100) were used. Rocket growth was inhibited by NH₄ nutrition, while it reached the highest values with the NH₄:NO₃ ratio 50:50. Water and N‐use efficiencies increased in rocket with the increase of NO₃‐N percentage in the nutrient solution. In the best conditions of N nutrition, however, rocket accumulated NO₃ in leaves in a very high concentration (about 6,300 mg kg^‐1 fresh mass). For all the morphological and yield features analyzed, chicory resulted to be quite unresponsive to N chemical forms, despite it took more NO₃‐N than NH₄‐N when N was administered in mixed form. By increasing NO₃‐N percentage in the nutrient solution, NO₃ leaf content increased (5,466 mg kg^‐1 fresh mass with the ratio NH₄:NO₃ 0:100). On average, both chicory cultivars accumulated 213 mg NO₃ kg^‐1 fresh mass with the ratio NH₄:NO₃ 100:0 and, differently from rocket, they showed that by using NH₄ produce can be obtained very low in NO₃ content.     

不同铵硝比对菠菜生长、安全和营养品质的影响

通过水培试验,研究了等氮条件下5种不同铵硝比对菠菜生长和品质的影响。结果表明:(1)从铵硝比100∶0到0∶100,菠菜地上部鲜重不断增加,铵硝比为0∶100时,菠菜的鲜重达最大值;但铵硝比25∶75和0∶100两个处理菠菜的干物重没有显著差异(p<0.05)。(2)随着铵硝比的降低,菠菜茎叶中硝酸盐、亚硝酸盐的含量均表现为线性增加;菠菜茎叶中可溶性草酸的含量和营养液中铵硝比之间呈现出二次曲线相关,在铵硝比为25∶75时,菠菜茎叶中草酸含量最低。适当增施铵态氮有利于降低菠菜硝酸盐、亚硝酸盐及草酸的含量。(3)增铵可以提高菠菜Vc含量,铵硝比为50∶50的处理菠菜Vc含量最高;随着铵硝比的下降,菠菜茎叶中可溶性糖的含量逐渐降低,而粗蛋白的含量则以铵硝比25∶75处理最高。     

Effects of Nitrogen Form and Concentration on Yield and Quality of Cucumbers Grown on Rockwool During Spring and Winter in Southern Greece

The influence of nitrogen concentration and the ratio of NO₃ to NH₄ on the marketable yield and fruit quality characteristics of cucumbers (Cucumis sativus L. cv. Palmera) grown on rockwool during spring and winter in southern Greece were studied. Nitrogen (N) was supplied at three N concentrations and four ratios of NO₃ to NH₄. During the spring, increasing total nitrogen or NH₄ concentration within the nutrient solution significantly decreased the mean total yield and fruit size. However, during the winter, the yield and number of fruits per plant were not affected by N concentration, but were reduced by increasing NH₄:NO₃ ratio. Fruits that were produced under low N concentrations were lighter in color, but only the color of the apical tissues of the fruit was affected by the NH₄:NO₃ ratio. Flesh firmness of the fruit was not affected by N source or concentration, except for the apical tissue, the firmness of which declined with increasing N concentration. On the basis of the present results, for highest yield and fruit quality during both the spring and winter seasons of southern Greece, 100 ppm N applied solely in the form of NO₃ is indicated.     

Comparison between nitrate and ammonium nutrition in fennel,celery, and Swiss chard

Abstract

To evaluate the chance to reduce leaf NO₃ content and to increase capability to use NH₄‐N even in the absence of NO₃‐N in the nutrient solution, plants of two Apiaceae species, fennel (Foeniculum vulgare Miller var. azoricum Mill. Thell.) and celery (Apium graveolens L. var. dulce Mill. Pers.), and of one species of Chenopodiaceae, Swiss chard (Beta vulgaris L. var. vulgaris), were hydroponically grown in a growth chamber with three different NH₄‐N: NO₃‐N (NH₄: NO₃) ratios (100: 0,50: 50, and 0: 100), but with the same total N level (4 mM) for 14 days. Swiss chard growth was inhibited by NH₄ nutrition and reached the highest values with the NH₄: NO₃ ratio 0: 100. For all the morphological and yield features analyzed, fennel and celery resulted to be quite unresponsive to nitrogen (N) chemical form. Water use efficiency increased in Swiss chard and decreased in fennel and celery with the increase of NO₃‐N percentage in the nutrient solution. The dependency of N uptake rate on shoot increment per unit root was more conspicuous for Swiss chard than fennel and celery. All species took more NO₃‐N than NH₄‐N when N was administered in mixed form. In the best conditions of N nutrition, Swiss chard accumulated NO₃ in leaves in high concentration (3,809 mg kg"¹ fresh mass). On average, fennel and celery accumulated 564 mg NO₃ kg^?1 fresh mass with the ratio NH₄: NO₃100: 0 and showed that by using NH₄ produce having very low NO₃ content can be obtained. By increasing NO₃‐N percentage in the nutrient solution; NO₃ leaf content of fennel and celery increased remarkably (7,802 mg kg^?1 fresh mass with the ratio N H₄: NO₃ 0: 100).     

DEVELOPMENT OF A SOIL N TEST FOR FERTILIZER REQUIREMENTS FOR WHEAT

Optimal fertilizer nitrogen (N) rates result in economic yield levels and reduced pollution. A soil test for determining optimal fertilizer N rates for wheat has not been developed for Quebec, Canada, or many other parts of the world. Therefore, the objectives were to determine: 1) the relationship among soil nitrate (NO^? ₃)- N, soil ammonium (NH ⁺ ₄)- N and N fertilizer on wheat yields; and 2) the soil sampling times and depths most highly correlated with yield response to soil NO^? ₃-N and NH ⁺ ₄-N. In a three year research work, wet and dried soil samples of 0- to 30- and 30- to 60-cm depths from 20 wheat fields that received four rates of N fertilizer at seeding and postseeding (plants 15 cm tall) were analyzed for NH ⁺ ₄-N and NO^? ₃ -N using a quick-test (N-Trak) and a standard laboratory method. Wheat yield response to N fertilizer was limited, but strong to soil NO^? ₃-N.     

Poinsettia growth,tissue nutrient concentration,and nutrient uptake as influenced by nitrogen form and stage of growth

Growth, development, and uptake of essential nutrients as influenced by nitrogen (N) form and growth stage was evaluated for ‘Freedom’ poinsettias (Euphorbia pulcherrima Willd. Ex Klotz.). Treatments consisted of five nitrate (NH₄ ⁺):ammonium (NO₃ ^‐) ratios (% NH₄ ⁺:% NO₃ ^‐) of 100:0, 75:25, 50:50, 25:75, and 0:100 with a total N concentration of 150 mg L^‐1. Plants were grown in solution culture for ten weeks under greenhouse conditions. Nutrient uptake data was combined into three physiological growth stages. Growth stage I (GSI) included early vegetative growth (long days). Growth stage II (GSII) began at floral induction and leaf and bract expansion (short days). Growth stage III (GSIII) was from visible bud through anthesis and harvest. Dry weights for all plant parts and height increased as the ratio of NO₃ ^‐ increased. Leaf area and bract area were maximized with 25:75 and 50:50 N treatments, respectively. Nitrogen treatments significantly affected foliar nutrient concentrations with calcium (Ca⁺⁺) and magnesium (Mg⁺⁺) being highest when NO₃ ^‐ was the predominant N form. Uptake of each macronutrient was averaged across all treatments and divided into physiological growth stages (GS) to identify peak demand periods during the growth cycle. The greatest uptake of NH₄ ⁺ and NO₃ ^‐ was from the early vegetative stage to floral induction (GSI). Phosphorus (P), potassium (K⁺), and Mg⁺⁺ uptake were greatest from floral induction to visible bud (GSII) and Ca⁺⁺ uptake remained relatively unchanged through GSI and GSII. Uptake was lowest for all nutrients from visible bud to anthesis (GSIII). Results from this study clearly indicate that peak demand periods for macronutrient uptake existed during the growth cycle of poinsettia.     

Effects of nitrogen form,nighttime nutrient solution strength,and cultivar on greenhouse tomato production

Higher greenhouse tomato (Lycopersicon esculentum Mill.) yield is obtained by using 25% of NH₄‐N in solution compared to using NO₃‐N as the sole nitrogen (N) source. However, blossom‐end rot (BER) may occur in tomato fruit when NH₄‐N was present in nutrient solutions. High nutrient solution strengths improve tomato fruit quality, but can also increase BER. Two NH₄‐N concentrations in solution (0 and 25%), and two nighttime solution strengths (NSS) (1X and 4X Steiner solution strength applied at 7 p.m.) were used to grow five indeterminate type greenhouse tomato cultivars: Caruso, Jumbo, Match, Max, and Trust. A significant interaction occurred between NH₄‐N concentration and NSS factors: 0% NH₄‐N and high NSS increased marketable yield and fruit:whole plant ratio, and reduced BER. In contrast, a concentration of 25% NH₄‐N and high NSS reduced marketable yield and the fruit:whole plant ratio, and increased BER incidence. Max, Match, and Trust tomato cultivars produced high marketable yield and high dry weight of stem and leaves, but were susceptible to BER. Use of NH₄‐N in solution reduced vegetative growth, and high NSS increased stem and leaf dry weight of the tomato plants. Fruit firmness was greater for the Max cultivar, and was unaffected by NH₄‐N and NSS at the mature green, breaker, and red ripe fruit development stages. However, at the fully ripe stage, fruit firmness was higher with high NSS and with 25% NH₄‐N.     

Potassium,nitrogen, ammonium/nitrate ratio,and sodium chloride effects on wheat growth

Fertigation with KNO₃ as a means of reducing salinity hazards was tested with peanut (Arachis hypogaea) plants grown on dune sand, resulting in a reduction of plant growth and yield. The objective of this work was to study the interactions between N, K⁺ and NaCl as well as the effects of the NH₄ ⁺/NO₃ ^‐ ratio on vegetative and reproductive growth. Wheat (Triticum aestivum L.) plants were grown in polyethylene pots with fine calcareous dune sand with different proportions of NH₄ ⁺ and NO₃ ^‐, under saline (60 mM NaCl) and non‐saline conditions. Three replicates were harvested at the beginning of flowering, and one was grown to grain maturity. NaCl reduced shoot dry weight in all the treatments. Increasing the NH₄ ⁺ proportion in the total of 6 mM N in the nutrient solution, increased shoot dry weight, did not change nitrogen concentration in the dry mass but increased P percentage, either with or without 60 mM NaCl. The number of tillers produced in each treatment was correlated with dry matter yield. The effect of the NH₄ ⁺/NO₃ ^‐ ratio may be explained by alteration of the cation‐anion balance on the nutrient uptake by roots, which lowered pH of the nutrient solution with increasing NH₄ ⁺ concentration, by alteration of the cation‐anion balance on the nutrient uptake by roots, which lowered pH of the nutrient solution with increasing NH₄ ⁺ concentration.     

氮素形态对川芎生长、产量与阿魏酸和总生物碱含量的影响

采用田间试验研究了硝态氮、铵态氮、酰胺态及不同硝态氮与铵态氮配比对川芎生长发育和产量与品质的影响。结果表明,硝态氮、铵态氮、酰胺态及硝态氮与铵态氮配施均可在一定程度上促进川芎的生长,延长其根长,茎蘖数增加,干物质积累增加,从而显著提高川芎的产量以及阿魏酸和生物碱含量。在硝态氮、铵态氮和酰胺态氮单独施用时,以尿素的增产增收和改善品质的效果最好,硝态氮最差;硝态氮与铵态氮配施可增强其肥效,延长其肥效持续期。高产高效的最佳施肥方式是50%的硝酸钙与50%的碳酸铵配施;优质高产的最佳施肥方式是75%的硝酸钙与25%的碳酸铵配施。