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.     

Modification of yield and chlorophyll content in leaf lettuce by HPS radiation and nitrogen treatments

This study evaluated the potential of high photosynthetic photon flux (PPF) from high-pressure sodium (HPS) lamps, alone or in combination with metal halide (MH) plus quartz iodide (QI) incandescent lamps, to support lettuce growth, with or without N supplementation. Varying exposures to radiation from combined HPS, MH, and QI lamps influenced dry weight gain and photosynthetic pigment content of hydroponically grown Black-Seeded Simpson' lettuce (Lactuca sativa L.) seedlings. Cumulative leaf dry weight declined with increasing exposure, up to 20 hours per day, to 660 micromoles m-2 s-1 of photosynthetically active radiation (PAR) from HPS lamps concomitant with constant 20 hours per day of 400 micromoles m-2 s-1 from MH + QI lamps. Leaves progressively yellowed with increasing exposure to radiation from the three-lamp combination, corresponding to lower specific chlorophyll content but not to specific carotenoid content. Lettuce grown under 20-hour photoperiods of 400, 473, or 668 micromoles m-2 s-1 from HPS radiation alone had the highest leaf dry weight at a PPF of 473 micromoles m-2 s-1. Chlorophyll, but not carotenoid specific content, decreased with each incremental increase in PPF from HPS lamps. Doubling the level of N in nutrient solution and supplying it as a combination of NH4+ and NO3- partially ameliorated adverse effects of high PPF on growth and pigment content relative to treatments using single-strength N as NO3-.     

Nickel supplementation effect on the growth,urease activity and urea and nitrate concentrations in lettuce supplied with different nitrogen sources

Effect of nickel (Ni) in the nutrient solution on yield, N metabolism, and nitrate content of leafy vegetables is poorly understood. The aim of this nutrient solution culture experiment was to investigate the effects of Ni supplementation on the nitrogen (N) metabolism and growth of lettuce (Lactuca sativa L. cv. Baker) with either urea or nitrate as the N source. Nickel supplement at 0.04 μM reduced urea toxicity to the urea-fed plants. Addition of Ni to the nutrient solution significantly increased the leaves and root growth of the urea-fed lettuce plants while it increased the growth of lettuce plants fed with nitrate only at N level of 20 mM. At N level of 20 mM, the leaves fresh weight of the urea-fed plants promoted by Ni supplement was comparable with the nitrate-fed plants untreated with Ni. Nickel supplementation increased the leaf total N concentrations in the urea-fed plants, although the nitrate-fed plants accumulated greater N in their leaves compared with urea treated plants at without Ni treatment. Nickel addition decreased the concentrations of leaf urea-N in the urea-fed plants and NO₃-N in the nitrate-fed plants. Nickel addition enhanced urease activity in the leaves of urea-fed plants. The results indicated Ni supplementation enhances the growth of the urea-fed lettuce plants while it has role in decreasing leaf nitrate concentration and thus, improving the health quality of the nitrate-fed plants.     

Effects of artificial light sources on accumulation of phytochemical contents in hydroponic lettuce

Lettuce is grown in different parts of the world and it is beneficial for health. Light condition is one of the most important environmental factor in regulating growth, development, and phytochemical accumulation in lettuce, particularly when lettuce is produced in a hydroponic system. Due to advances in technologies, artificial light sources have become increasingly capable of providing appropriate quality, intensity, and photoperiod of light in hydroponic lettuce production. This review highlights the progress of current research on the effects of artificial light regulation on growth and phytochemical accumulation in lettuce produced in hydroponic systems.     

Effects of nitrogen availability on the biomass and nitrogen partitioning in Brussels sprouts (Brassica oleracea var. gemmifera)

Summary

The effect of rate and date of application of nitrogen fertilizer on the partitioning of biomass and nitrogen in Brussels sprouts was studied in field experiments. Growth of Brussels sprouts was in two phases: during the first phase mainly leaves and stem were produced and during the second phase mainly bud growth occurred. At the onset of bud growth, 60–80% of the total biomass was produced and an equal proportion of nitrogen had been taken up. Final bud weight and bud nitrogen content correlated positively with the total biomass and nitrogen content at the onset of bud growth. Partitioning of biomass and nitrogen among the different above-ground plant organs was hardly affected by the nitrogen availability and the time of the fertilizer application. Harvest index at the final harvest was 0.25 for the biomass and 0.45 for nitrogen. During bud growth, leaf senesced at a high rate. Biomass and, especially, nitrogen was remobilized from the leaves before shedding. During bud growth the decrease in nitrogen content of the leaves was up to 50% of the nitrogen increase of the buds. When additional N was applied at the onset of bud growth, N remobilization decreased. An N application at the onset of bud growth increased bud growth due to a delay of leaf shedding. Nitrogen concentration in the buds increased due to a N application at the onset of bud growth, which resulted in a greener appearance. When a certain amount or nitrogen was split into two portions (half at transplanting and half at the onset of bud growth) the nitrogen concentration of the buds was higher than when applied completely at transplanting only, but the partitioning of biomass and the bud yield was not affected.     

Effects of foliar-applied nitrogen during winter on growth,nitrogen content and production of passionfruit

The effects of foliar-applied nitrogen (11.5 g N l⁻¹) during winter on growth, nitrogen content and production of passionfruit (Passiflora edulis f. edulis × P. edulis f. flavicarpa cultivar E-23 grafted onto P. edulis f. flavicarpa) was investigated in subtropical Queensland, Australia. Vegetative growth and flowering were severely restricted during winter in the untreated vines, despite the maintenance of leaf nitrogen levels within the range presently believed to be optimum for Queensland conditions after nitrogen was applied to the soil in autumn. Foliar urea applications during winter (monthly or twice monthly) increased leaf nitrogen levels but reduced growth and subsequent fruitlet number.Reductions in vegetative growth during winter in passionfruit appear to be due to a direct effect of cool soil and/or air temperatures, unrelated to nitrogen uptake, translocation and leaf nitrogen level.     

The effect of nitrogen fertilization on plant growth and the nitrate content of leaves and roots of parsley in the Mediterranean region

Curly-leafed and turnip-rooted parsley have recently been introduced to Greece as alternative herbs within the programme for crop diversification. Because the response of these subspecies to nitrogen (N) application under the warm climatic conditions of the Mediterranean region is unknown, both were cultivated over three consecutive years in order to evaluate their yield potential and quality (in terms of nitrate content) in relation to nitrogen application in comparison with the traditionally cultivated plain-leafed subspecies. Nitrogen was applied as ammonium nitrate in the form of liquid feeds at rates of 30–450 mg kg⁻¹. Foliage and root yield increased with N application up to a level of 150 mg kg⁻¹ and the nitrate content of the tissues was low. Increasing N application rates to 300 or 450 mg kg⁻¹ did not cause a further increase in yield, but the nitrate content of the tissues increased. In view of health concerns with respect to human nitrate intake and environmental threats posed by excessive N application, it is concluded that the optimum level of ammonium nitrate application under local conditions should be 150 mg kg⁻¹. Overall, all three subspecies responded to N in a similar way in terms of yield and nitrate content.     

Influence of nitrogen form,growing season and sulfur fertilization on yield and the content of nitrate and vitamin C of broccoli

The objective of this study was to determine the effects of nitrogen (N) sources, sulfur (S) and growing seasons on yield and the content of nitrate and vitamin C of broccoli (Brassica oleracea L. spp. Italica). Three N fertilizers (ammonium sulfate, ammonium nitrate and urea) were side-dressed while two levels of sulfur (0.0 and 0.5%) were sprayed on broccoli plants grown in both spring and fall-winter seasons. Here, we report on the interaction between N-source and S supply, yield, and nitrate content and discuss the relevance of this interaction in relation to crop-management strategies under different growing seasons. In the fall-winter season, broccoli yield of “Sultan F1”, “Majestic F1” and “Marathon F1” were 21.23%, 128.52% and 88.53% higher than spring season. Furthermore, S application increased the yield by 9% average over growing seasons, cultivars and N-forms. Also, application of urea as N-source decreased the yield by approximately 13–15% than other N-sources. High curd nitrate accumulation was attributed with spring season and “Marathon F1”, however, less accumulation was found in fall-winter season and “Majestic F1”. Fertilizers containing N forms that not ready available to the crop, i.e. ammonium sulfate and urea, decreased nitrate than fast N-release fertilizer (ammonium nitrate), but their effect on the yield was different. Highest yield with low content of nitrate was achieved when ammonium sulfate combined with sulfur were used during fall-winter season, especially in cv. “Marathon F1”. N-source and sulfur application had no effect on vitamin C, conversely, it was affected by growing season and tested genotypes. Therefore, additions of ammonium sulfate and sulfur application in the field of broccoli were essential to produce higher yield with good quality curds that pose minimum health risk to human.     

Effect of temperature on photosynthesis of lettuce adapted to different light and temperature conditions

Gas exchange of lettuce plants, pre-grown in growth chambers at different irradiances (18, 37, 70 W m^?2) and temperatures (6, 14, 22°C) were measured in the range of 2–22°C. In weak light (18 W m^?2) there was no increase in CO₂ uptake above 2°C, and even in 70 W m^?2 the highest rates were obtained at about 10°C only. The response of net photosynthesis of lettuce to temperature is diminished as a result of morphological plant adaptations, i.e. specific leaf area or top-to-root weight ratio. The temperature optimum for dry-matter production is much higher than that for CO₂ uptake. Therefore, photosynthesis is an unsuitable criterion for temperature control in greenhouses.     

Effect of 16 and 24 hours daily radiation (light) on lettuce growth

A 50% increase in total radiation by extending the photoperiod from 16 to 24 hr doubled the weight of all cultivars of loose-leaf lettuce (Lactuca sativa L.) 'Grand Rapids Forcing', 'Waldmanns Green', 'Salad Bowl', and 'RubyConn', but not a Butterhead cultivar, 'Salina'. When total daily radiation (moles of photons) was the same, plants under continuous radiation weighed 30% to 50% more than plants under a 16 hr photoperiod. By using continuous radiation on loose-leaf lettuce, fewer lamp fixtures were required and yield was increased.     

刺梨实生苗对硝态氮、铵态氮的吸收与利用差异分析

【目的】研究刺梨(Rosa roxburghii Tratt.)对NO_3~-、NH_4~+的吸收动力学特性及其利用差异,探究不同供氮浓度和不同温度条件下刺梨对NO_3~-和NH_4~+的吸收特性,为刺梨氮肥施用提供科学依据。【方法】以‘贵农5号’刺梨品种实生苗为材料,采用耗竭法和砂培试验的方法,测定了供给不同形态及配比的氮素后刺梨实生苗对NO_3~-和NH_4~+的吸收动力学参数及氮素的吸收量与利用效率,研究不同供氮浓度及温度变化和不同硝铵比氮素条件下刺梨实生苗对NO_3~-和NH_4~+的吸收与利用效率的差异。【结果】刺梨根系对硝态氮、铵态氮及总氮的吸收规律均符合Michaelis-Menten酶动力学方程。在不同浓度的NO_3~-、NH_4~+条件下,刺梨根系对NO_3~-的最大吸收速率、亲和力及在根系中的流速始终高于NH_4~+。在硝态氮与铵态氮不同配比的供氮条件下,根系对NO_3~-、NH_4~+的最大吸收速率和NO_3~-、NH_4~+在根系中的流速都随着硝、铵比例的增加而增大,硝铵比为3∶1的供氮条件下,刺梨根系对总氮的吸收速率和总氮在根中的流速最大,最有利于刺梨对氮素的吸收,刺梨实生苗的生物量、总氮的吸收量和氮的利用效率最大。介质的温度过低或过高都会降低刺梨根系对NO_3~-和NH_4~+的吸收,显著降低NO_3~-、NH_4~+的最大吸收速率和NO_3~-、NH_4~+在根系中的流速;无论温度如何变化,刺梨根系对NO_3~-的最大吸收速率和NO_3~-在根系中的流速始终比NH_4~+高。在20~25℃有利于刺梨对NO_3~-和NH_4~+的吸收。【结论】刺梨具有偏好吸收硝态氮的特性,在单纯供给硝态氮或混合供给硝铵态氮硝铵比1∶1及以上的条件下,刺梨实生苗根系对NO_3~-的最大吸收速率、亲和力和NO_3~-在根系中的流速始终比NH_4~+高,刺梨偏好硝态氮的特性不会因介质中NO_3~-和NH_4~+的浓度及温度的变化而改变。介质温度20~25℃有利于刺梨对氮的吸收,供给硝铵比3∶1的氮肥最有利于刺梨实生苗的生长,生物量、氮素吸收量最大,氮素利用效率最高。     

Effect of organic and inorganic fertilizers applied during successive crop seasons on growth and nitrate accumulation in lettuce

A romaine-type lettuce (Lactuca sativa L.) cv. Corsica was cultivated during three successive crop seasons (late-spring, late-autumn and late-winter) in the same soil of an experimental greenhouse in S.W. Peloponnese, Greece. Seven long-term fertilization treatments were tested for their effect on plant growth and nitrate concentration in the external lettuce leaves. Treatments included: three different doses of organic fertilization (composted sheep manure) applied at the start of each crop season, three different doses of inorganic N fertilization applied via fertigation during each crop season, and a control treatment in which no fertilizer was applied. A drip irrigation system was used to water all plants. The highest nitrate levels were observed in the medium and maximum inorganic fertilization treatments (572–664 mg kg⁻¹) in all crop seasons. They were significantly higher compared to the respective organic fertilization treatments (253–435 mg kg⁻¹) and all other fertilization treatments (148–435 mg kg⁻¹). Crop season affected lettuce growth more than nitrate accumulation in the lettuce leaves: lettuce biomass production was the smallest and most uniform in the late-autumn season and did not respond to the fertilization treatments tested (ranging from 409 to 439 g plant⁻¹), while in the late-spring season biomass production was the highest and most variable (561–841 g plant⁻¹), it correlated with nitrate concentration in the leaves and in the medium and maximum inorganic fertilizer doses it significantly exceeded production from all other fertilization treatments (827–841 g plant⁻¹). Following the three crop seasons the residual availability of N, P and K was clearly enhanced in the soil receiving the organic compared to the inorganic fertilization. Nitrate concentration in lettuce leaves was far below the upper limits set by the European Commission in all fertilization treatments throughout the three crop seasons, a result attributed mainly to the sufficient level of light intensity and duration throughout the year in Southern Greece.     

Effects of salinity on nitrate,total nitrogen,soluble protein and free amino add levels in tomato plants

The effects of salinity on nitrogen compounds were studied in three tomato (L. esc- ulentum Mill.) genotypes of different salt tolerance. The plants were grown under controlled conditions, and the salt treatments (0, 70 and 140 raM NaCl) were applied for three (Harvest 1) and ten (Harvest 2) weeks. The effects of salinity on total N and particularly N03 concentrations depended partly on the NaCl level and duration of the stress, but mainly on the different degrees of salt tolerance of the genotypes. In Harvest 1, the most tolerant genotype (GC-72) showed the highest N03 increase in the roots and no decreases in stem and leaf with increasing salinity; the intermediate-tolerant genotype (P-73) showed a similar response to that of GC-72 only at 70 mM NaCl. However, the most sensitive genotype (Volgogradskij) showed the greatest reductions in stem and leaf N03 concentrations with salinity. With longer durations of stress the different responses between the more tolerant genotypes were less evident; only Volgogradskij continued to show the highest decreases in stem and leaf N03 concentrations. A restriction of N03 transport from the root to the shoot was noted in the plants of the more tolerant genotypes treated for three weeks. This capacity for retention disappeared when the salinity induced reductions in the total N03 contents in the plants, as in the harvest 2. There was an inverse relation between N03 and Cl accumulations in shoots of all genotypes and its slope decreased with the salt sensitivity of the genotype. There was no relation between the leaf protein content and the salt tolerance of the tomato genotypes. In Harvest 1, a higher accumulation of amino acids, especially proline, was found in the leaves of the more tolerant genotypes at 140 mM NaCl. However, in Harvest 2, a similar accumulation of leaf proline was found in all genotypes, independent of their salt tolerances, and the other amino acid contents remained similar or else decreased with salinity.     

Effects of soil temperature on head development of Cos lettuce

Cos lettuce plants (Lactuca sativa L. cultivar ‘Romana’) of 2 ages were grown for 30 days with soil temperatures of 12°, 20°, 28° or 36°C. The highest temperature caused poor growth and heading and quick head disintegration. Best heading occurred mainly at lower temperature, although the lowest one sometimes delayed growth. Higher temperatures did not enhance real bolting, as growth of the inner stem was accelerated.     

不同碳氮源培养蛹虫草液体菌种及栽培试验

以葡萄糖、蔗糖、麦芽糖、乳糖为供试碳源,各碳源浓度均设为10g/L、15g/L、20g/L、25g/L、30g/L;以硫酸铵、蛋白胨、酵母粉、尿素为供试氮源,各氮源浓度均设为6g/L、8g/L、10g/L、12g/L、14g/L。分别制作液体菌种培养基培养蛹虫草液体菌种,并将获得的液体菌种用于栽培蛹虫草试验。测定蛹虫草液体培养菌丝生物量、子实体鲜重及子实体多糖含量。结果表明:在液体菌种培养阶段,最佳碳源为25~30g/L的蔗糖,最佳氮源为6g/L酵母粉;以20g/L蔗糖作为碳源,10g/L硫酸铵为氮源培养液体菌种栽培蛹虫草产量最高;以10g/L葡萄糖为碳源,12g/L蛋白胨为氮源培养基上培养的液体菌种栽培蛹虫草子实体多糖含量较高。     

Form and development of nitrogen in plant waste extracts,effects of papain on nitrogen transfer and use of extracts for lettuce fertigation

Summary

Liquid organic fertilisers made from extracts of plant residues can provide a sustainable alternative for vegetable production, since they are not produced using fossil fuels and are easy to apply as side-dressing fertilisers. The aims of this study were: (i) to evaluate the influence of extraction time and the addition of papain on the composition of aqueous extracts of cauliflower, tomato leaf, or whole tomato plant residues; and (ii) to explore the fertigation potential of such extracts for lettuce cultivation. After 10 d of extraction, approx. 30% of all plant residue nitrogen (N) was transferred to the liquid fraction, of which 8 – 15% was in mineral form. Ammonium was the main mineral form of N in all extracts. Nitrate concentrations were higher in whole tomato plant residues than in tomato leaves or cauliflower residues. The addition of papain increased the amount of total N in solution when used at concentrations ≥ 400 mg l^–1.

Compared to the mineral nutrient solution (control), plant extracts were comparable in mineral N, lower in phosphate, and higher in all other nutrients examined, as well as in Na⁺ and Cl^– ions. The application of each extract to lettuce seedlings resulted in reduced plant growth in all treatments compared to the control, probably due to their higher electrical conductivity and, possibly, ammonium toxicity. Further research is needed in order to balance the nutrient composition and to increase the transfer of plant residue nutrients into the extracts.     

Effects of flat plastic film covering and tunnel protection on the development of early lettuce

The results of trials with lettuce that was given a temporary cover of polythene sheets of 0.05 mm thickness after being planted in the open in March, indicate that the covering should not be removed until the minimum soil temperature at a depth of 10 cm reaches 4°C. This occurred in 1973 after 14 days when planting on March 7th, and after 7 days when planting on March 19th. The results obtained with perforated polythene were better than with unperforated sheeting.It is possible to advance cropping by 1 week at least. A temporary cover always improves the weight of heads and this is attributed to the increased water content of covered plants and to their larger number of heavier — and therefore probably also larger — leaves. The $\text{length}\text{width}$ ratio of leaves was smaller in plants that were given temporary cover than in those that had not been covered.The differences referred to were considered to be mainly due to the more favourable temperatures under the plastic film and therefore also with improved root development in the first stages of the plant's life.     

腐殖酸水溶性肥料对莴苣产量和效益的影响

为了解施用腐殖酸水溶性肥料对莴苣产量和效益的影响,以便在生产上推广应用,笔者在莴苣生长期进行了施用试验。结果表明,在莴苣旺盛生长期和茎部肥大期,每667m2用腐殖酸水溶性肥料100mL加水50kg进行叶面喷施,能够使莴苣产量提高170kg以上,增产率在7%以上,667m2可增加收入200元,投入产出比达到1∶10。莴苣喷施该肥料,技术简单实用,增产增效明显,建议在生产上推广应用。     

南瓜砧木促进西瓜嫁接苗的氮利用效率研究

<正>目的与意义:氮是植物生长发育所必需的大量营元素,其主要以硝酸根(NO_3~-)的形式被植物所吸收。嫁接作为克服土传病害,消除连作障碍的一项有效技术措施,在西瓜生产上已得到广泛应用。然而,关于嫁接西瓜氮效率的研究较少。本文以南瓜砧木为材料,研究砧木对西瓜接穗氮利用效率的影响,并探讨其中的生理机制。     

添加佐剂对CPPU处理的翠冠梨果实生长与品质的影响

为了减少CPPU引起的不良效应,探讨了在CPPU溶液中添加不同佐剂对翠冠梨果实生长及品质的影响。结果表明,盛花后第2周用20mg/L CPPU处理可以促进果实膨大,提高单果质量,并延迟果实成熟。CPPU单独处理增加畸形果比率,而添加0.1% Triton或者PVAC作为佐剂则可减少畸形果的发生,并增强CPPU处理效应,因此,在CPPU使用过程中不应忽视佐剂的作用。