Responses of cucumber plant to NH4 and NO3 nutrition: The relative addition rate technique vs. cultivation at constant nitrogen concentration

Different N sources (NO₃⁻, NH₄⁺, or NH₄NO₃) at different relative addition rates (RAR) were supplied to cucumber (Cucumis sativus L.), a species sensitive to NH₄⁺ toxicity. For comparison, cucumber plants were also grown at constant concentrations of 1 and 5 mM NH₄⁺ or 5 mM NO₃⁻. The fresh weight of NH₄⁺-fed plants at RAR 0.15 and RAR 0.25 day⁻¹ was similar to that of NO₃⁻-fed plants, while at RAR 0.35 or RAR 0.45 day⁻¹ growth reduction occurred. When available as a constant concentration, NH₄⁺ decreased plant growth at 5 mM. It is concluded that at low rates of N supply the relative addition rate technique can be used for growing cucumber plants with NH₄⁺ as sole N source without deleterious effects.     

Effects of source,rate, and frequency of N application on yield,marketable grades and rot incidence of sweet onion (Allium cepa L. cv. Granex-33)

In a field experiment in the 1988-89 season, fertilizer formulations of NH₄NO₃, Ca(NO₃)₂, NaNO₃, NaKNO₃, and KNO₃ as N sources were applied at 84 and 168 kg N ha^?1 to onion plots direct seeded in the fall. A second experiment in the 1990-91 season tested the same N sources, except KNO₃, at rates of 168 and 224 kg ha^?1. Application strategy involved both splitting the total amount of fertilizer over two periods of the growing season (October–December and January—April) and the application frequency. With medium and high application rates (168 and 224 kg ha^?1), NH₄NO₃, NaNO₃, and NaKNO₃, increased high-value jumbo and large onions (premium marketable grade). Increased premium grades was due to increased bulb size and weight. Only NH₄NO₃ and Ca (NO₃)₂ increased total onion weight when N rate was increased from 84 to 168 kg ha^?1. Less frequent applications of split amounts of 84 kg N ha^?1 reduced marketable weight in the 1988–89 season, but doubling the rate to 168 kg ha^?1 restored the higher yields. At 224 kg N ha^?1 in the 1990–91 season, differences in onion grades were more pronounced among the different N sources, and NH4 NO₃ was superior in producing jumbo and large size onions. High N rates (224 kg ha^?1) and more frequent applications of split portions also increased the weight of jumbo onions. Split applications, providing 33% of the total N in the first 12 weeks of the growth period plus three applications of 22% each in the second 12 week period, increased bulb size and maximized yield of premium marketable grades. Effect of N rate on onion rot was dependent on split methods of applying the N during early and late growth periods. However, reduction in onion rot by the split application strategy was dependent on N source. Bulb decay was highest with NH4NO₃ and least with Ca(NO₃)₂ and NaNO₃.     

Nutrient solution effects on the development and yield of Anthurium andreanum Lind. in tropical soilless conditions

The fertilization of anthurium grown in soilless culture in tropical countries is often empirically based. The methods used generally lead the grower to overestimate plant needs and to apply excessive quantities of nutrients. Mineral elements, and thus money, are wasted and there is a risk of pollution of groundwater and watercourses. In order to improve our knowledge of plant requirements, we measured, over 2 1/2 years, the growth and yield of anthurium plants receiving nutrient solutions with different total nitrogen, potassium and calcium concentrations and different NH₄⁺/NO₃⁻ ratios. Mineral analyses of plant parts, of nutrient, leachate and substrate solutions and of the solid substrate were carried out throughout plant development. Plants receiving 4.5 mmol N/l and 1.6 mmol K/l in the nutrient solution had significantly slower growth and lower yield compared to those receiving 8.9 mmol N/l and 3.2 mmol K/l. For these latter N and K concentrations, a N–NH₄⁺/N–NO₃⁻ ratio of 0.37 and a calcium concentration of 1.15 mmol/l gave better plant growth, development and yield than a ratio of 0.24 and a calcium concentration of 2.25 mmol/l. Applying the nutrient solution containing 8.9 mmol N/l and 3.2 mmol K/l with a N–NH₄⁺/N–NO₃⁻ ratio of 0.37 resulted in a shorter vegetative period and more and larger flower production. The calculated mineral balances of the crop showed that more than 60% of the supplied nutrients were lost in the leachate. Suitable nutrient solutions are proposed in order to match plant absorption at different crop growth stages. The volume of nutrient solution supplied can be reduced to limit the amount of leachate, but as water demand is high, there must be at least 30% of leaching to avoid salt accumulation in the substrate. Adjusting the nutrient solution volume and composition to match plant requirements is the first step for flower yield improvement, fertilizer efficiency and reduction of pollution.     

The effects of pre-sowing seed treatments on the germination and emergence of lettuce seeds at high salt concentrations

Radicle emergence in lettuce seeds cultivar ‘Hilde’ was reduced by NH₄NO₃ above 8×10^?2M, while radicle extension was inhibited by 8×10^?2M NH₄NO₃ and no seedlings emerged. Inhibition of radicle emergence by 8 and 16×10^?2M NH₄NO₃ was prevented by soaking seeds for 4 h before sowing in a mixture of $\text{GA}{}_{\mathrm{<mtext>4</mtext><mtext>7</mtext>}}$ and kinetin+phosphate buffer, and was partially prevented by soaking them for 4 h before sowing in phosphate buffer. These treatments did not prevent inhibition of radicle emergence by 32×10^?2M NH₄NO₃, but seeds soaked in growth regulators or phosphate buffer before sowing and taken from this NH₄NO₃ solution after 7 days and washed to remove excess salt gave 45–52% germination compared with 12 % for untreated seeds. Pre-treatment of the seeds did not prevent the inhibitory effect of NH₄NO₃ on radicle extension. In field experiments seeds treated with growth regulators + phosphate buffer or phosphate buffer alone gave a higher final percentage emergence from soils given 125 kg N/ha than did untreated seeds.     

Effects of N fertilizers and rates on yield,safety and nutrients in processing spinach genotypes

Two field experiments were carried out at the Experimental Field, Department of Food Science (TE, Italy) in 2004 and 2005 to evaluate the effects of genotypes, different N forms and N rates on yield, safety and nutritional features of processing spinach. Experiment 1, as treatments, included spinach genotypes and N forms (CO(NH₂)₂; Agricote; NH₄NO₃); experiment 2 included three N forms (Ca(NO₃)₂; (NH₄)₂SO₄; NH₄NO₃) applied at rates of 0, 75, 150, 200 kg N ha⁻¹. This research work confirmed differences among spinach genotypes in terms of efficiency in N use and oxalate and nitrate accumulation. Spinach accumulated much more nitrate in petioles and much more oxalate in blades indicating that nitrate and oxalate might play a counterrole to each other. Fertilizers containing N under forms not readily available to the crop, i.e. Agricote, CO(NH₂)₂ and (NH₄)₂SO₄, increased nitrate and oxalate accumulations less than fast N-release fertilizers, but their effect on yield was limited. Highest yield with contents of nitrate and oxalate lower than the limits imposed to avoid health problems, were achieved with Ca(NO₃)₂, at rates of 130 and 150 kg N ha⁻¹ NH₄NO₃.     

Japanese holly growth and release pattern of ammonium and nitrate from controlled-release fertilizers

Applications of 0.85, 1.70 or 2.55 kg N m^?3 were made to Ilex crenata Thunb. Hetzi. Nitrogen sources included weekly applications of liquid fertilizer (NH₄NO₃) and single application of TVA's Sulfur coated urea (SCUT), Gold N (SCUG), Nitroform (NITR), isobutylidene diurea (IBDU), and an experimental N-containing Osmocote (OSCN). Shoot dry matter and leaf N from recently matured leaves were determined. Analyses of NH₄-N and NO₃-N were also conducted on the monthly leachates collected from the containers. Most controlled-release fertilizers (CRFs) produced greater dry weights at 1.70 kg N, while NH₄NO₃ produced more dry weight than CRF's at 0.85 or 2.55 kg N. Initially, for CRF's ammonium was more abundant than nitrate in the leachate; subsequently, nitrate became the dominant N form for most of the growing-season. All urea-based fertilizers had higher NH₄ levels in the leachate when compared with NH₄NO₃-based fertilizers.     

Effect of nitrogen form and radiation on growth and mineral concentration of two Brassica species

Three greenhouse experiments were carried out to determine the growth, yield, nitrate, total N and S concentration in shoots, and water uptake of hydroponically grown Brassica rapa L. subsp. nipposinica var. chinoleifera and Brassica juncea L. In each experiment, daily photosynthetically active radiation (PAR) level was 5.0 mol m⁻² (low), 6.8 mol m⁻² (medium) or 9.0 mol m⁻² (high). Plants were supplied with nutrient solutions having equal N concentrations of 11 mM in different forms: 100% NH₄, 50% NH₄ + 50% NO₃, and 100% NO₃. Nitrogen supplied as 100% NH₄ reduced fresh and dry shoot biomass, leaf area, and leaf number in both Brassica species, especially at low and medium PAR levels. In both Brassica species, S concentrations were highest, while nitrate concentrations were lowest in leaves of plants grown at N supplied as 100% NH₄. No differences in leaf nitrate concentrations were observed between 50% NH₄ + 50% NO₃ and 100% NO₃ treatments. Low and high PAR levels increased the nitrate concentrations and decreased the N/S ratio in leaves of both crops compared to medium PAR level. Fresh shoot biomass was maximized in Brassica rapa when PAR level was above the medium value and nitrate was supplied in the nutrient solution as NO₃ or as a mixture of 50% NO₃ and 50% NH₄. The highest fresh shoot biomass of Brassica juncea was observed in all nutrient solution treatments at high PAR level.     

The effect of various nitrogen fertilization and foliar nutrition regimes on the concentrations of nitrates,ammonium ions,dry matter and N-total in carrot (Daucus carota L.) roots

Two field experiments (Experiment I in 2003–2005 and Experiment II in 2004–2005) with carrot c.v. ‘Kazan F₁’ were conducted at Trzciana village (50°06′N, 21°85′E). The experiments were arranged in a split-plot design with four replications. Two sub-blocks were identified in both experiments: I, without foliar nutrition; II, receiving plant foliar nutrition. The plants were sprayed three times alternately with: 2% urea solution, 1% solution of multi-component ‘Supervit R’ fertilizer (produced by Intermag, Poland) and again with 2% urea solution. Combinations with diversified nitrogen fertilization were distinguished within both sub-blocks. Experiment I comprised of: (1) Control, (2) Ca(NO₃)₂ 70, (3) Ca(NO₃)₂ 70 + 70, (4) (NH₄)₂SO₄ 70 and (5) (NH₄)₂SO₄ 70 + 70. Experiment II included: (1) Control, (2) ENTEC-26 35 + 35, (3) ENTEC-26 70 + 70, (4) ENTEC 26 105 + 105, (5) NH₄NO₃ 35 + 35, (6) NH₄NO₃ 70 + 70, (7) NH₄NO₃ 105 + 105. Where 70 kg N ha⁻¹ was used before sowing, whereas 35 + 35, 70 + 70 and 105 + 105 kg N ha⁻¹ were applied before sowing and as top dressing. Solid nitrogen fertilizer was added to the soil (produced by): Ca(NO₃)₂, Yara International ASA (Hydro); (NH₄)₂SO₄, Zak?ady Azotowe in Tarnów, Poland; NH₄NO₃, Zak?ady Azotowe in Pu?awy, Poland; and ENTEC-26, COMPO GmbH & Co. KG, Germany. The research aimed at determining the effect of diversified nitrogen fertilization and foliar nutrition on NO₃⁻, NH₄⁺, N-total and dry matter (d.m.) concentrations in carrot, and N uptake by storage roots. In Experiment I, nitrogen fertilization did not affect NO₃⁻ concentration, whereas in Experiment II, the applied N treatment increased NO₃⁻ concentration in carrot in relation to the control, except for the storage roots of plants fertilized with ENTEC-26 35 + 35. Nitrogen fertilization applied in both experiments caused a significant increase in N-total concentration in carrot and N uptake by storage roots in comparison with the control plants. In both experiments, nitrogen fertilization had a different effect on the concentrations of NH₄⁺ and d.m. in carrot. What is more, foliar nutrition treatments in both experiments had a different effect on the concentrations on NO₃⁻, N-total, d.m. in carrot and N uptake by carrot storage roots.     

Meristem culture and micropropagation of a variety of ginger (Zingiber officinale Rosc.) with a high yield of oleoresin

Summary

Meristems of ginger with or without leaf primordia were induced to form shoots on three-quarter strength Murashige-Skoog’s (MS) medium containing sucrose 6%, coconut milk (CM) 20%, ascorbic acid (AA) 100 mg l^?1, glutamine (GL) 400 mg l^?1, activated charcoal (AC) 250 mg l^?1, 6-benzylaminopurine (BAP) 0.5 mg l^?1, indolebutyric acid (IBA) 0.4 mg l^?1 and agar 0.8%. Meristem-derived shoots exhibited consistent multiplication on three-quarter strength MS medium containing sucrose (3%), AA (100 mg l^?1), AC (100 mg l^?1), BAP (4–5 mg l^?1) and agar (0.8%). Liquid media (agitated or static) were less effective than a solid (agar-gelled) medium for micropropagation. Kinetin and naphthalene acetic acid (NAA) incorporated at various levels (0.01–0.8 mg l^?1) with or without added BAP and IBA neither improved plantlet formation nor enhanced shoot multiplication. The in vitro plants were successfully established in vivo and the rhizome yield was comparable with that of plants grown by conventional methods.     

Nitrogen-enriched ground kenaf (Hibiscus cannabinus L.) stem core as a component of soilless growth media

Summary

Four experiments showed that stem core (xylem of kenaf (Hibiscus cannabinus L.) in combination with sphagnum peat moss and fertilizer nutrients was a satisfactory growth medium for plants of ‘Toy Boy’ tomato (Lycopersicon esculentum Mill.). Greater shoot growth was achieved in media containing 20 to 35% kenaf by volume than 50%, and with fine kenaf (2–4 mm diameter) than coarser grades. In the absence of weekly solution fertilization, N-enrichment of the kenaf was necessary to support greater shoot growth than occurred in commercial growth media. Soaking the kenaf in solutions of increasing nitrogen (N) concentration (0 to 15,000 mg N l^?1) increased shoot growth, but urea ammonium nitrate (UAN, 30N–0P–OK) generally resulted in greater shoot growth than 20N–4.4P–16.6K at the same N concentration. The soaking time for kenaf in UAN was considerably less than in the complete fertilizer to produce similar shoot dry weights. Only a small portion of the kenaf in the growth media required pre-plant N enrichment provided the N concentration of the soak solution was increased in ‘ proportion to the volume reduction. Increasing the N concentration of weekly solution fertilization (20N–4.4P–16.6K) from 0 to 500 mg N l^?1 increased shoot growth irrespective of the N concentration of the kenaf soak solution. In media receiving 0 or 100 mg N l^?1 weekly solution fertilization, shoot growth increased with increasing N concentration of the kenaf soak solution.     

Effects of nitrate,ammonium and chloride application on the yield and nitrate content of soil-grown lettuce

Summary

The effect of nitrogen availability and nitrogen form on the yield and nitrate content of butterhead lettuce (Lactuca sativa var. capitata L.) grown in soil under greenhouse conditions was studied. The extent to which chloride application can reduce nitrate content by supplying the plant with an alternative osmotically active anion, and whether the presence of ammonium in the soil is a necessary prerequisite for an effect of chloride, was also examined. Reducing NO₃-N availability from 260 to 200 kg N ha^–1 significantly reduced nitrate content while head fresh weight was unaffected. Further reducing NO₃-N availability to 120 kg N ha^–1 significantly reduced both nitrate content and fresh weight. Substituting 40% of the available NO₃-N with NH₄-N significantly reduced nitrate content while fresh weight was unaffected. The effect of NH₄-N application on plant nitrate content was enhanced by the application of the nitrification inhibitor dicyandiamide (DCD). Despite increasing chloride uptake, the application of chloride had no significant effect on head fresh weight or nitrate content when available nitrogen was in the nitrate form irrespective of the level of nitrogen application. Chloride application similarly had no effect on head fresh weight or nitrate content when applied together with ammonium without the nitrification inhibitor DCD, despite a greater uptake of chloride. Where both ammonium and DCD were applied, however, chloride application significantly reduced head nitrate content.     

Recurrent somatic embryogenesis and plant regeneration in Coriandrum sativum L.

An efficient method of repetitive somatic embryogenesis and plant regeneration was established in Coriandrum sativum L. Embryogenic callus was induced from cotyledon and hypocotyl segments on Murashige and Skoog (MS) medium with 4.52 μM 2,4-dichlorophenoxy acetic acid (2,4-D), upon subculturing on medium having same level of 2,4-D at an interval of 3 weeks developed somatic embryos, which progressed to cotyledonary stage through early developmental stages of somatic embryogenesis. The transfer of somatic embryos at an early cotyledonary and cotyledonary stage in clumps in succession to fresh 4.52 μM 2,4-D supplemented medium developed embryos in a cyclic manner. Upon transferal to embryogenic clumps (cotyledonary embryos) to modified MS medium (4 g l⁻¹ KNO₃, 0.29 g l⁻¹ NH₄NO₃, 3 mg l⁻¹ thiamine HCl, 0.5 mg l⁻¹ pyridoxine HCl, and 5 mg l⁻¹ nicotinic acid), the embryos irrespective of the cycles underwent maturation and germination. Germinating embryos transferred to half-strength MS medium favored healthy growth of plantlets. The system of recurrent somatic embryogenesis in coriander offers a system for genes transfer and also scale-up production of modified plants.     

Castanea sativa plantlets proliferated from axillary buds cultivated in vitro

Chestnut plants were proliferated in vitro from axillary buds of juvenile shoots. N6-Benzyl-aminopurine (BAP) at 0.1?0.5 mg l^?1 was optimal for shoot multiplication. The important role played by the macronutrient formula on shoot multiplication, and especially on the rooting-stage, is emphasized. The MS ($\text{1}\text{2}$ NO₃) macronutrients gave the best rooting percentage as well as the highest number of roots per rooted shoot. In these experiments, shoots remained in the 3 mg l^?1 indole-3-butyric acid (IBA) medium for 12 days, after which they were transferred to an auxin-free medium where roots developed fully. Optimum rooting was achieved by immersing the 1 cm basal end of shoots in concentrated IBA solutions (0.5?1 mg ml^?1) for periods ranging from 2 to 15 min.     

The influence of wax emulsion,morphactin and gibberellic acid on the storage behaviour of indian gooseberry fruits

Qualities of Indian gooseberry fruits (Phyllanthus emblica L.) were determined after dip-treatment with wax emulsion (WE) with or without morphactin (Mor) and gibberellic acid (GA₃). Dip-treatments with 100–500 mg l^?1 Mor reduced marketability by inducing browning and high weight loss, but loss in ascorbic acid was checked and phenols increased. 10 mg l^?1 Mor maintained marketability at par with control, effectively controlled loss in ascorbic acid, and increased acidity and reducing sugars. GA₃, although failing to control the loss of ascorbic acid, was effective in checking browning and thereby increased the market value of fruits as compared with controls and Mor-treated fruits.WE with or without Mor (10 mg l^?1) controlled browning, accumulation of phenols and losses in weight and moisture as compared with 10 mg l^?1 Mor, 100 mg l^?1 GA₃, or control, but could not retain ascorbic acid in comparison to 10 mg l^?1 Mor-treated fruits. Marketability of fruits having had treatment with either WE or GA₃ was the same. Fruits having had combined treatment with WE and 10 mg l^?1 Mor had maximum marketability. Minimum marketability was observed in fruits subjected to a combined treatment of WE + 100 mg l^?1 GA₃ due to maximum infection with Aspergillus spp. and Penicillium spp.     

Effects of NH4:NO3:urea ratio on cut roses yield, leaf nutrients content and proton efflux by roots in closed hydroponic system

The effects of the NH₄:NO₃ ratio in replenishment solution on Rosa L. flower yield and the impact of NH₄ substitution by urea on plant performance and on solution EC and pH have not been studied previously in closed (no leaching) hydroponic systems. A greenhouse experiment with six NH₄:NO₃:urea ratios (0:100:0, 12:88:0, 25:75:0, 50:50:0, 100:0:0 and 0:50:50) and two harvest cycles (winter and spring) was carried out to investigate these relationships. In winter, total and >40 cm cut flower yields were maximal in treatment 25:75:0. At lower NH₄ percentages (12.5:87.5:0 and 0:100:0), growth container solution pH varied between 7.8 and 8.5, reducing P, Ca and Mn concentration in leaves and increasing dry matter allocated to them. At higher NH₄ percentages, Ca uptake was inhibited, solution pH reached 3, and %P in leaves increased. Consequently, reducing sugars concentration in leaves increased and sucrose and starch concentrations decreased. A stepwise regression analysis indicated that the optimal NH₄:NO₃ ratio in feed solution is 40:60, with resulting solution pH of 5.9 in the growth container. In spring the maximum yield was obtained in treatment 0:50:50 and it exceeded the winter yield despite a higher solution EC (4.3 dS m⁻¹ vs. 3.5 dS m⁻¹ at harvest). The beneficial effect of urea (0:50:50 vs. 50:50:0) stemmed from the relatively lower NH₄ concentration in solution, that alleviated the NH₄–Ca uptake competition, and higher pH. The slope of the straight line relating [H⁺ efflux rate] to [NH₄⁺ uptake rate] in treatments 25:75:0, 50:50:0 and 100:0:0 was 0.44 mol H⁺/mol NH₄. In all other treatments the proton efflux was negligible.     

The effect of various nitrogen fertilization and foliar nutrition regimes on the concentrations of sugars,carotenoids and phenolic compounds in carrot (Daucus carota L.)

The aim of this research was to determine the influence of various forms, diverse doses, and dates of application of nitrogen fertilizers and foliar nutrition on the concentration of sugars, carotenoids and phenolics compound in carrot. Two field experiments (Experiment I in 2003–2005 and Experiment II in 2004–2005) with carrot ‘Kazan F₁’ were conducted in Trzciana (50°06′N; 21°85′E) in Poland. Both experiments were arranged in a split-plot design with four replications. Two sub-blocks were identified in both experiments: sub-block (A) without foliar nutrition and sub-block (B) with plant foliar nutrition. In sub-block (B), plants were sprayed three-times with: 2% (w/v) urea, a 1% (v/v) solution of multi-component ‘Supervit R’ fertilizer, and again with 2% (w/v) urea. Combinations with diversified nitrogen fertilization were distinguished within both sub-blocks. The treatments in Experiment I consisted of: (1) Control, (2) 70 kg N ha⁻¹ as Ca(NO₃)₂, (3) 70 + 70 kg N ha⁻¹ as Ca(NO₃)₂, (4) 70 kg N ha⁻¹ as (NH₄)₂SO₄ and (5) 70 + 70 kg N ha⁻¹ as (NH₄)₂SO₄, where 70 kg N ha⁻¹ was used preplant and 70 + 70 kg N ha⁻¹ was applied preplant and as a top dressing, respectively. The treatments in Experiment II consisted of: (1) Control, (2) 35 + 35 kg N ha⁻¹ as ENTEC-26, (3) 70 + 70 kg N ha⁻¹ as ENTEC-26, (4) 105 + 105 kg N ha⁻¹ as ENTEC-26, (5) 35 + 35 kg N ha⁻¹ as NH₄NO₃, (6) 70 + 70 kg N ha⁻¹ as NH₄NO₃, (7) 105 + 105 kg N ha⁻¹ as NH₄NO₃, where 35 + 35, 70 + 70, 105 + 105 kg N ha⁻¹ was applied preplant and as top dressing, respectively. Solid nitrogen fertilizer was added to the soil, as produced: Ca(NO₃)₂—Yara International ASA (Hydro), (NH₄)₂SO₄—Zak?ady Azotowe w Tarnowie, Poland, NH₄NO₃—Zak?ady Azotowe w Pu?awach, Poland and ENTEC-26–COMPO GmbH & Co., KG, Germany. In Experiment I, the highest sugar concentrations were found in carrot fertilized with (NH₄)₂SO₄ 70, while in Experiment II in the control and after fertilization with ENTEC-26 35 + 35 kg N ha⁻¹. In both experiments N-fertilization affected an increase in phenolic compound concentrations in comparison with the control. Experiment I revealed no significant effect of N-fertilization on carotenoid concentrations in carrot, however in Experiment II the highest concentration of these compounds was characteristic for the control plants and carrot fertilized with ENTEC-26 35 + 35. The foliar nutrition applied in Experiment I caused a decline in sugar concentration and an elevated carotenoid concentration, however it had no influence on the phenolic compound concentrations in carrot. Yet the foliar nutrition in Experiment II led to a decrease in phenolic and carotenoid compound concentrations, but it did not affect sugar concentration in carrot.     

Vegetative growth and nutritional status as influenced by auxins and gibberellic acid,and their effect on fruit yield in lemon

Application of 2,4-D and 2,4,5-T at concentrations ranging from 5 to 20 mg l^?1 to 5-year-old ‘Pant Lemon-1’ (Citrus limon Burm) trees reduced the vegetative growth in terms of height, spread, shoot length, number and size of the leaves in the autumn flush. Various NAA treatments (5–20 mg l^?1), however, enhanced growth, but not to the extent that was observed after GA₃ treatments. Application of GA₃ at 10–40 mg l^?1 significantly enhanced all aspects of growth, and the effects were most pronounced at 20 and 40 mg l^?1. Nutritional status of the leaves showed a slight variation in relation to vegetative growth under various treatments.Some 2,4-D- and 2,4,5-T-treatments increased the fruit yield over the control, which could suggest mobilization of foods even at the expense of reduced vegetative growth. On the other hand, NAA, particularly at 10 mg l^?1, increased both vegetative growth and yield, suggesting that the transport of the photosynthates from the leaves to the fruits was not at the expense of new growth extension. Due to excessive growth enhancement under higher concentrations of GA₃ (20 and 40 mg l^?1), comparatively fewer nutrients were translocated to the fruit “sinks”, thereby resulting in a non-significant decrease in yield.     

不同铵硝配比对芥蓝伤流液组分及植株氮磷钾积累的影响

采用伤流液组分分析和植物营养分析的方法,探讨了不同铵硝配比（CK,0∶100;T1,10∶90;T2,25∶75;T3,50∶50）影响芥蓝生长的生理机制。结果表明：与全硝态氮营养液对照相比,3 个营养液增铵处理均提高了芥蓝植株的生物量和伤流强度,其中营养液增铵25%（T2）处理的效果最好。T1 处理芥蓝植株伤流液中蛋白态氮和P 的流量与CK 相比显著增加;T2 处理芥蓝植株伤流液中NO₃^--N、P、K 流量均为最高;T3 处理芥蓝植株伤流液中NH₄⁺-N、氨基酸态氮和蛋
白态氮流量最高,而NO₃^--N 和K 流量则显著低于CK。T1 处理和T2 处理显著提高了芥蓝植株N、P、K 的含量和积累量;T3 处理亦显著提高了芥蓝植株N、P 的含量和积累量,但显著降低了K 的含量和积累量。综合来看,营养液适量增铵（25%）处理的效果最好,可以提高芥蓝根系吸收能力,促进氮代谢,增加植株对N、P、K 的吸收和积累,从而促进植株生长。     

Development of a medium for in vitro culture of Galanthus species based on the mineral composition of bulbs

Summary

To optimise conditions for micropropagating Galanthus species, a basal medium (G) was developed based on mineral analyses of G. nivalis, G. nivalis ‘Flore Pleno’ and G. elwesii bulbs. Compared with Murashige and Skoog (MS) medium, the main features of G medium were increased concentrations of Cu ( 30.4), P ( 3.6), Ca ( 1.9), Mg ( 1.3) and S ( 1.2) and reduced levels of Mn ( 0.07), Zn ( 0.59) and K ( 0.65). The efficacy of G medium in supporting bulblet initiation on bulb chip explants, bulblet multiplication (on media supplemented with 30 g l^–1 sucrose, 1.0 mg l^–1 6-benzylaminopurine and 0.1 mg l^–1 naphthalene acetic acid), and bulblet growth (on plant growth regulator-free media with 60 g l^–1 sucrose and 5 g l^–1 activated charcoal) was compared with MS medium over a range of dilutions (full-, ¹?2-, ¹?4-, and ¹?8-strength). Bulblet initiation was superior on G medium for G. nivalis and G. nivalis ‘Flore Pleno’, but inferior for G. elwesii. The choice of basal medium did not influence bulblet multiplication, although multiplication was reduced on both media diluted to ¹?8-strength. G medium supported bulblet growth and rooting better than MS medium, while dilution of either medium reduced bulblet growth and rooting. Using G medium in place of MS medium during bulblet multiplication greatly reduced hyperhydration with G. elwesii, as did dilution of either of the basal media.     

Effect of methyl jasmonate on reactive oxygen species,antioxidant systems,and microstructure of Chinese winter jujube at two major ripening stages during shelf life

The effect of post-harvest application of methyl jasmonate (MeJ) on reactive oxygen species, antioxidant systems, and cellular structure in Chinese winter jujube (Ziziphus Jujuba Mill.) at the major ripening stages of green maturity (GM) and half-red maturity (HM) were investigated. Jujube fruit at each ripening stage were treated with 0, 50, 100, and 200?μmol?l^?1 MeJ for 24 h, then stored at 20 ± 2°C for shelf-life testing. Thereafter, changes in firmness, color, respiration rate, superoxide anion (O₂^?), hydrogen peroxide (H₂O₂), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), ascorbic acid (AsA), and glutathione (GSH) were measured at 4-d intervals for up to 8 d. Results showed that, in comparison with control fruit, MeJ treatment effectively suppressed the decrease of firmness, color, and respiration rate, inhibited the production of O₂^? and accumulation of H₂O₂ and MDA, maintained higher activities of SOD and CAT and contents of AsA and GSH, and preserved the integrity of cell membranes and organelles. The degree of maturity influenced the benefits of MeJ application. The 100?μmol?l^?1 MeJ treatment had a positive impact on antioxidant systems for GM fruit, whereas a MeJ concentration below 100 μmol l^?1 was found to extend the shelf life of HM fruit.