Detection and quantitation of resveratrol in tomato fruit (Lycopersicon esculentum Mill.)

Resveratrol is a stilbene phytoalexin well-known for its presence in grape, wine, and peanut. As a result of its antioxidant and chemopreventative properties, it has gained much attention as a functional food ingredient. A gas chromatography-mass spectrometry method for the detection of resveratrol, its 3-glucopyranoside piceid, and the cis isomers of both compounds has been developed and used to quantitate the levels of these compounds in the skin of commercially available tomato fruit (Lycopersicon esculentum Mill.). The resveratrol concentration remains relatively stable during fruit maturation, reaching a maximum concentration in the skin of 18.4 +/- 1.6 microg/g dry weight at 4 weeks postbreaker. No stilbenes were detected in the flesh of tomato fruit.     

Plant regeneration from hypocotyl and cotyledon explant of tomato (Lycopersicon esculentum Mill.)

Three tomato cultivars were used to examine the influence of the genetic background on the regeneration efficiency. White embryonic calli were formed within two weeks of culture. Shoots emerged either directly from the explant or indirectly from the embryonic callus. Multiple adventitious shoots were formed by clonal propagation of somatic embryos in the presence of 2 mg zeatin L^-1. The meristematic end of the hypocotyl of the cultivar Pontaroza showed a high regeneration frequency (70.2%) compared with the cotyledonary leaf explant (35.3%). The plants grown in the green house and the regenerants obtained showed a similar peroxidase banding pattern. The combined analysis of variance indicated that the difference in shoot induction between cultivars was highly significant. Shoot induction frequency was 57.2%, 43.5%, and 35.5% for the cultivars UC-97, Pontaroza, and Zuishi, respectively. The regeneration frequency was 50%, 28%, and 20% for the cultivars UC-97, Pontaroza, and Zuishi, respectively. The observed differences in shoot induction between cultivars were due to the genetic difference between them.     

Iodine application affects nitrogen-use efficiency of lettuce plants (Lactuca sativa L.)

Abstract

The main objective of this work was to determine whether nitrogen-use efficiency was affected by the application of different forms (iodide vs iodate) and dosages (20, 40 and 80 µM) of iodine, to ascertain the influence of this trace element in a biofortification programme in lettuce plants. The parameters analysed were root and shoot biomass, nitrate concentration, and organic and total nitrogen as well as those defining nitrogen-use efficiency in plants: total nitrogen content, total nitrogen accumulation, nitrogen-uptake efficiency and nitrogen-utilization efficiency. In addition to decreasing shoot biomass, iodide treatments reduced leaf levels of nitrates, organic nitrogen, and total nitrogen content. Iodate treatments did not affect the concentration of nitrogen in its different forms. The application of iodide caused total nitrogen accumulation and nitrogen-uptake efficiency to decrease, iodate application improved the latter. Both iodide and iodate applications significantly improved nitrogen-utilization efficiency in comparison to the control. The results obtained show that iodate application rates of 40 µM or lower significantly improved all nitrogen parameters analysed, making it possible to increase lettuce productivity and quality.     

Response surface optimization of cultivation conditions for yield of tomato (Lycopersicon esculentum Mill.) in greenhouses

There is a great potential for greenhouse tomato fruit yield improvement in China for the low yield per hectare. We evaluated the effects of multi-factors (plant density, nitrogen (N) and K₂O fertilizer) on fruit yield of tomato (Lycopersicon esculentum Mill. cv. Jinfan 4) by response surface methodology with a 5-level-3-factor central composite design. A multivariate quadratic regression model of fruit yield was established. Results showed that N fertilizer was the most significant for fruit yield, followed by K₂O fertilizer and plant density. Fruit yield showed a parabolic trend with increasing fertilizer levels or plant density. There was a significant interaction effect between plant density and fertilizer levels. Optimal conditions were obtained: 4.83 × 10⁴ plants ha^?1 for density, 262 kg ha^?1 for N and 513 kg ha^?1 for K₂O. Under these conditions, the predicted fruit yield was 119,381 kg ha^?1, while the actual fruit yield from verification test was 121,005 kg ha^?1.     

Chloride interaction with nitrate and phosphate nutrition in tomato (Lycopersicon esculentum L.)

Tomato plants were grown in a greenhouse in 100 liter containers containing nutrient solutions. A 4 × 3 × 3 factorial experiment of Cl × N × P was conducted. The Cl^‐ concentrations were 0, 10, 35 and 70 meq/1; NO^‐ ₃ concentrations were 7.5, 15, and 20 meq/1; and H₂PO^‐ ₄ concentrations were 1, 2, and 5 meq/1. Fifteen different plant parameters were analyzed. There was a decline in dry matter yield with increasing Cl^‐ concentration in solution at all NO, and H₂PO^‐ ₄ levels. The effect of NO^‐ ₃ levels on dry matter at each Cl^‐level was varied and resulted in a significant Cl^‐ x NO^‐ ₃ interaction. The Cl^‐ affected all measured plant parameters but K and P content in the plant. Chloride content in the plant was depressed by increasing NO^‐ ₃ concentration in the solution at all levels of Cl^‐ in the solution. There was a little effect of H₂ PO^‐ ₄ on Cl^‐ and Mg content in the plant. The possibility of using NO^‐ ₃ fertilizers to depress Cl^‐ uptake by the plants is discussed.

Interaction between solution salinity and plant nutrition was investigated for several crops by Bernstein et al. (1974). Their experiments were conducted at relatively low nutrient solution concentrations which contained only 2 and 4 meq/l of NO^‐ ₃. Low NO^‐ ₃ concentrations are justified when very low C1^‐ concentrations are present in solution. Letey et al. (1982) did not find any response of tomato to increases in NO^‐ ₃ concentration beyond 1 meq/l in a chloride‐free solution. Hiatt and Leggett (1974) reported that increasing Cl^‐ concentration in the solution suppressed NO^‐ ₃ uptake by the plant. Direct competition between NO^‐ ₃ and Cl^‐ on uptake by plants was also reported by DeWit et al. (1963). There is therefore a possibility that yield reduction due to increased salinity is not entirely from Cl^‐ toxicity, but may be partially due to induced deficiency of NO^‐ ₃ by the increased external Cl^‐concentration (Wallace and Berry, 1981).

Reports on the effect of H₂FO^‐ ₄ interaction with salinity are conflicting (Champagnol, 1979). Some investigators report positive and others report negative effects of increased H₂PO^‐ ₄ concentrations on plant resistance to salinity. Nieman and Clark (1976) found that decreasing H₂PO^‐ ₄ from 1 to 0.1 meq/l increased resistance of the plant to salinity.

The purpose of the work reported herein was to check the hypotheses that increasing NO^‐ ₃ and H₂PO^‐ ₄ concentrations in the nutrient solution will decrease Cl^‐ uptake and thus increase plant resistance to Cl^‐ salinity or conversely high Cl^‐ in the water requires higher NO^‐ ₃ concentration for adequate N supply as compared to low Cl^‐.     

Alkylperoxyl radical scavenging activity of red leaf lettuce (Lactuca sativa L.) phenolics

Although lettuce may provide relatively low levels of antioxidative phytochemicals which may contribute to human health, lettuce leaf extracts in fact contained compounds with high specific peroxyl radical scavenging activities. After determining the extraction conditions that minimized phenolic oxidation and produced the highest oxygen radical absorbance capacity (ORAC) values, the phenolic compounds from red leaf lettuce were separated by reverse-phase high-performance liquid chromatography (HPLC). The primary phenolic compounds in the leaf tissue extracts were mono- and dicaffeoyltartaric acid (CTA and DCTA), mono- and dicaffeoylquinic acid (CQA and DCQA), quercetin 3-malonylglucoside (QMG), quercetin 3-glucoside (QG), cyanidin 3-malonylglucoside (CMG), and an unknown phenolic ester (UPE). Significant levels of DCQA were only found after wounding. Using the new fluorescein-based ORAC assay procedures, fractions from the HPLC analyses were assayed for peroxyl radical absorbance capacity. Using absorbance to estimate concentration, the decreasing order of contribution to the total ORAC value of an extract from wounded tissue was QMG > DCQA > CMG > DCTA > UPE > QG > CTA. The decreasing order of the specific peroxyl radical scavenging activities was CMG > QG > DCTA > DCQA > QMG > UPE > CQA > CTA. Since the concentrations of plant flavonoid and phenolic acid esters are sensitive to environmental factors, this information may be used to develop pre- and postharvest conditions which increase the dietary benefits of leaf lettuce.     

Utilization of some organic wastes as growing media for lettuce (Lactuca sativa L.) plants

Abstract

The environmental impact of crop wastes and the high cost of peat moss (PM) force scientists to find alternative growing media. In a pot experiment, peanut shell (PS) and corn wastes (CWs) were evaluated as growing media in comparison with PM in three different mixing ratios with washed sand. The mixing ratio were M₁?=?1:1 raw material to sand, M₂?=?1:2 raw material to sand, and M₃?=?1:3 raw material to sand. The tested plant was lettuce (Lactuca sativa L.). The obtained results showed that PS medium contained available nitrogen (N) and phosphorus (P) higher by 121% and 38% above the PM medium. Availability of potassium (K) in CW medium was higher by 167% than PM. The EC, pH, OC, and C/N ratio of PM were higher by 227%, 4%, 128%, and 99% above the CW and by 1,473%, 9%, 74%, and193% above the PS, respectively. The highest significant values of growth parameters were recorded in PM medium. The highest total cost and lowest net profit were recorded with the use of PMM₁, whereas the lowest cost and the highest net profit were obtained with PSM₂. Physiochemical characteristics of peanut shell suggested that it can be economical alternative growing media for PM.     

Calcium and humic acid affect seed germination,growth, and nutrient content of tomato (Lycopersicon esculentum L.) seedlings under saline soil conditions

The effects of calcium and humic acid on seed germination, growth and macro- and micro-nutrient contents of tomato (Lycopersicon esculentum L.) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 2000 mg kg^?1) and calcium (0, 100, 200 and 400 mg kg^?1) were applied to growth media treated with 50 mg NaCl kg^?1 before sowing seeds. Seed germination, hypocotyl length, cotyledon width and length, root size, shoot length, leaf number, shoot and root fresh weights, and shoot and root dry weights of the plant seedlings were determined. Macro- and micro-nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of shoot and root of seedlings were also measured. Humic acid applied to the plant growth medium at 1000 mg kg^?1 concentration increased seedling growth and nutrient contents of plants. Humic acid not only increased macro-nutrient contents, but also enhanced micro-nutrient contents of plant organs. However, high levels of humic acid arrested plant growth or decreased nutrient contents. Levels of 100 and 200 mg kg^?1 Ca²⁺ application significantly increased N, Ca and S contents of shoot, and N and K contents of root.     

Stimulation of gamma-aminobutyric acid production in vine-ripe tomato (Lycopersicon esculentum Mill.) fruits under modified atmospheres

Stimulation of gamma-aminobutyric acid (GABA) production under low O2 and high CO2 conditions (adjusted aerobic atmosphere) under which ethanol fermentation could be avoided was studied. Vine-ripe tomato fruits were stored under hypoxia conditions and adjusted aerobic atmospheres as well as in the air at 15 degrees C for 13 days and at 30 degrees C for 6 days. At 30 degrees C tomato fruit GABA concentration under the adjusted aerobic atmosphere (O2 11%, CO2 9%) was significantly higher by 48% than that in air after 6 days from the start of storage. Increased accumulation of alanine under the adjusted aerobic atmosphere supports the observation that this atmosphere stimulates GABA production. The results demonstrate that the concentration of GABA as a beneficial substance for antihypertensive effects and so on can be increased by storing tomato fruits under adjusted aerobic atmospheres for the first time.     

基于主动冠层光谱仪的莴苣生物量及氮素营养状况估测

[目的]研究冠层光谱技术在蔬菜氮素营养诊断中应用的可行性和提高其准确性的方法,为推进蔬菜氮素营养管理与施肥推荐提供快速无损检测技术.[方法]以茎菜类蔬菜—莴苣(Lactuca sativa L.)为研究对象进行田间试验.设置5个化肥年施用梯度:0、108、162、216、270kg/hm2,在莴苣幼苗期、莲座期、茎形成...     

Genetic composition of contemporary proprietary U.S. lettuce (Lactuca sativa L.) cultivars

Pedigree history of 146 lettuce (Lactuca sativa L.) cultivars registered in the U.S. by Plant Variety Protection and/or utility patent of the era from 2000 through 2010 facilitates determination of coefficient of parentage among these cultivars, identification of ancestral parental lines, and their genetic contribution. Principal ancestors of leaf lettuce developed in this era are the cultivars ‘Malibu’, ‘Waldmann’s Green’, and ‘Salad Bowl’ contributing 6.4, 6.1, and 3.5% of the genes, respectively. The cultivars ‘Parris Island Cos’ and ‘Tall Guzmaine’ are major ancestors of romaine lettuce, contributing 25.9 and 23.4% of the genes, respectively. Three crisphead lettuce ancestors identified are the cultivars ‘Vanguard’, ‘Salinas’, and ‘Calmar’, the former two descend from interspecific crosses of L. sativa with Lactuca virosa L. and Lactuca serriola L. Among these three, ‘Vanguard’ is the major ancestor contributing 23.8% of the genes to crisphead lettuce. The crisphead cultivar ‘Salinas’ was frequently crossed with romaine lettuce types and the romaine parental cultivar ‘Parris Island Cos’ was crossed with leaf types contributing to romaine and leaf lettuce genetic diversity, respectively. Genetic similarity was less within leaf cultivars (coefficient of parentage = 0.02) than found within romaine (0.15) and crisphead (0.13) cultivars registered in the U.S. during this era.     

Effect of methyl jasmonate on phenolic compounds and carotenoids of romaine lettuce (Lactuca sativa L.)

The effect of exogenous methyl jasmonate (MeJA) on antioxidative compounds of romaine lettuce ( Lactuca sativa L.) was investigated. Lettuces were treated with various MeJA solutions (0, 0.05, 0.1, 0.25, and 0.5 mM) before harvest. Total phenolic compounds content and antioxidant capacity of romaine lettuce significantly increased after MeJA treatments (0.1, 0.25, and 0.5 mM). The total content of phenolic compounds of the romaine lettuce treated with 0.5 mM MeJA (31.6 microg of gallic acid equivalents/mg of dry weight) was 35% higher than that of the control. The increase in phenolic compound content was attributed to a caffeic acid derivative and an unknown phenolic compound, which also contributed to increased antioxidant capacity. The induction of phenylalanine ammonia-lyase (PAL) activity by the MeJA treatment indicated that phenolic compounds were altered due to the activation of the phenylpropandoid pathway. Total content of carotenoids, including lutein and beta-carotene, of the MeJA-treated lettuce did not change after 8 days of treatment, whereas the content of the control without MeJA decreased after 8 days. This research indicated that preharvest application of MeJA could increase the nutritional value of romaine lettuce under determined conditions discussed in this work.     

Amendment of hydroponic nutrient solution with humic acid and glutamic acid in tomato (Lycopersicon esculentum Mill.) culture

Abstract

Can humic acid (HA) and glutamic acid (GA), when added to tomato (Lycopersicon esculentum Mill. cv. ‘Hongyangli’) nutrient solution in a hydroponic system, improve growth? Tomato seedlings were grown in six nutrient solutions: (1) control (C), (2) C + 25 mg L^?1 HA (HA1); (3) C + 50 mg L^?1 HA (HA2); (4) C + 100 mg L^?1 GA; (5) HA1 + GA; (6) HA2 + GA. Various biochemical and physiological parameters were measured. HA increased photosynthesis rate and mesophyll conductance. HA did not significantly affect transpiration, stomatal conductance, titratable acidity, or antioxidant activity. In addition, GA improved protein and sugar content, mesophyll conductance and yield. The combination of HA and GA was more effective, especially with 50 mg L^?1 HA. The activity of superoxide dismutase (SOD) and peroxidases (POD) did not change in the presence of HA or GA. Malondialdehyde (MDA) content increased by 30% in HA2 together with GA. HA has a positive effect on tomato hydroponic growth when applied with GA. This expands the use of HA and GA for horticultural commodities in hydroponic systems.     

Evidence for a tetrameric form of iceberg lettuce (Lactuca sativa L.) polyphenol oxidase: purification and characterization

Polyphenol oxidase from iceberg lettuce (Lactuca sativa L.) chloroplasts was released from the thylakoid-membrane by sonication, and it was extensively purified to homogeneity as judged by SDS-PAGE. Purification was achieved by ammonium sulfate fractionation, gel-filtration chromatography, and ion-exchange chromatography. Two molecular forms were separated by gel-filtration chromatography with apparent molecular masses of 188 and 49 kDa. Both forms were characterized by sedimentation analysis with S(20,W) values of 10.2 and 4.1 S, respectively. For the high-molecular-weight form purified to homogeneity, denaturing SDS-PAGE indicated a molecular mass of 60 kDa. Thus, from these data we suggest that lettuce polyphenol oxidase is a tetramer of identical subunits.     

Peat replacement in horticultural growth media: the adequacy of coir,paper sludge and biogas digestate as growth medium constituents for tomato (Solanum lycopersicum L.) and lettuce (Lactuca sativa L.)

Purpose: Due to environmental concerns, efforts are made to replace the use of peat in horticultural growth media by organic wastes. Four growth media were prepared with the purpose of achieving adequate physical and chemical properties for plant production. Materials and methods: Growth media prepared from mixtures of coir (C) and paper sludge (P), respectively, with two biogas digestates from food waste (D₁ and D₂), were tested. These mixtures, 20% D₁ or D₂?+?80% C or P (v/v), were evaluated as growth media for tomato (Solanum lycopersicum L.) and lettuce (Lactuca sativa L.). Results and conclusion: The growth media were all physically stable during the growing period, provided all the macronutrients and most of the micronutrients necessary for plant growth, adequate pH conditions, as well as an adequate electrical conductivity. The mixture of D₂ and P produced the highest biomass compared to a mineral fertilised peat (control), with a biomass production of 76% of the control for lettuce and 54% for tomato. Causes for the biomass reduction relative to the control may be related to ammonium toxicity effects, and/or limited plant-available water. The digestates, particularly D₁, seemed also to have a phytotoxic effect on the germination.     

Growth survey of crisphead lettuce (Lactuca sativa L.) in fertilizer trial by low-altitude small-balloon sensing

Abstract

Both efficiency and precision of field-grown plant biomass survey are expected to be improved when aerial images of whole fields are acquired. Many such studies have been conducted in paddy rice (Oryza sativa L.), wheat (Triticum aestivum), and beans (Glycine max (L.) Merr. and Phasaeolus vulgaris), but few in vegetables. In this study, we examined whether or not aerial image analysis is useful for the biomass survey of vegetables. Aerial images of field-grown crisphead lettuce (Lactuca sativa L.) in a three-year fertilizer trial were acquired at head formation and harvesting stages in summer and autumn cropping with a compact digital camera hung under a tethered small balloon (2.2 m in length, 0.56 m³ in volume). The camera height ranged from 36 to 65 m, and the ground resolution ranged from 1.3 to 2.2 cm pixel ^?1. The horizontally projected area of the plant was measured as follows: Aerial images of the field were topographically corrected, the lettuce part was extracted based on the difference in color, the images were binarized, and the projected area was determined by image processing software. The estimation of fresh weight of one plant from the projected area was difficult because of the large data dispersion. When the averaged projected area in each plot was used, estimation was improved in some cases. Estimation of fresh weight at the harvesting stage by using the projected area at the head formation stage was difficult due to the low correlation coefficient. The results of factor analysis of fertilizer treatments by using projected area agreed well with those done using fresh weight when the correlation coefficient between the projected area and the fresh weight was high. It was concluded that the estimation of absolute lettuce fresh weight was difficult, but relative comparisons among treatments were possible until the head formation stage, using aerial images acquired by low-altitude small-balloon sensing.     

Salt in irrigation water affects the nutritional and visual properties of romaine lettuce (Lactuca sativa L.)

The influence of salinity stress on the growth, appearance, and nutritional compounds, especially phenolic compounds and carotenoids, of romaine lettuce (Lactuca sativa L.), a low salt tolerant plant, was studied. The dry weight, height, and color of the lettuce plants were significantly changed by long-term irrigation (15 days) with higher NaCl concentration (i.e., >100 mM). However, no significant differences were observed in the growth and appearance among the control, all short-term treatments (2 days; 50, 100, 500, and 1000 mM), and long-term irrigation with low salt concentration. Moreover, in romaine lettuce treated with long-term irrigation with 5 mM NaCl, the total carotenoid content increased without color change, and the contents of major carotenoids in romaine lettuce, lutein and beta-carotene, increased 37 and 80%, respectively. No differences were observed in lutein and beta-carotene contents in short-term-treated lettuce. The phenolic content of the romaine lettuce declined with short-term salt irrigation, whereas there were no significant differences among treatments exposed to long-term irrigation. This research indicates that long-term irrigation with relatively low salt concentration, rather than short-term irrigation with high salt concentration, can increase carotenoid content in romaine lettuce without causing a tradeoff in yield or visual quality.     

Roles of glycine betaine in mitigating deleterious effect of salt stress on lettuce (Lactuca sativa L.)

This study was conducted to evaluate the roles of glycine betaine (GB) in mitigating deleterious effect of salt stress on lettuce. Lettuce plants were subjected to two salinity (0 and 100 mmol l^?1 NaCl) and four GB levels (0, 5, 10, 25 mmol l^?1). Salinity resulted in a remarkable decrease in growth parameters, relative leaf water content and stomatal conductance. Plants subjected to salt stress exhibited an increase in membrane permeability (MP), lipid peroxidation (MDA), leaf chlorophyll reading value, H₂O₂ and sugar content. Exogenous foliar applications of GB reduced MP, MDA and H₂O₂ content in salt-stressed lettuce plants. Salt stress increased Na and generally decreased other nutrient elements. GB reduced Na accumulation, but significantly increased other element contents under salinity conditions. The study showed that gibberellic acid (GA) and salicylic acid (SA) content in salt-stressed plants were lower than those of nonstressed plants. However, salinity conditions generally increased the abscisic acid content. GB treatments elevated the concentrations of GA, SA and indole acetic acid (IAA) at especially 10 and 25 mmol l^?1 GB under salt stress conditions. It could be concluded that exogenous GB applications could ameliorate the harmful effects of salt stress in lettuce.     

Impact of liming on utilization of 59Fe‐chelates by lettuce (Lactuca sativa L.)

A pot experiment was conducted to determine the utilization of iron (Fe) by lettuce (Lactuca sativa L. cv. Australian gelber). Iron was applied as ⁵⁹Fe in inorganic and chelated form, particularly biodegradable chelate, ⁵⁹Fe‐EDDS. Two stereoisomeric forms of ethylenediaminedisuccinate: [S,S]‐EDDS and a mixture of EDDS containing 25% [S,S]‐EDDS, 25% [R,R]‐EDDS, and 50% [S/R]/[R/S]‐EDDS, ethylenediaminetetraaceticacid (EDTA) and ethylenediimino bis(2‐hydroxyphenyl)acetic acid (EDDHA) were used as ligands. Lettuce was grown in unlimed and limed quartz sand with nitrate as the sole source of nitrogen. Liming decreased lettuce yields but had no effect on Fe concentrations, indicating that Fe concentrations were a poor indicator of Fe bioavailability within the plant. In unlimed sand, utilization of ⁵⁹Fe from all ⁵⁹Fe‐chelates was on the same level (2.8%–3.6%). In limed sand, only ⁵⁹Fe‐EDDHA maintained the ⁵⁹Fe utilization on a level (3%) comparable to that in unlimed sand. Although the utilization of ⁵⁹Fe from the other chelates decreased to 0.6%–1.1% after liming, Fe concentrations were not affected due to the increased uptake of indigenous Fe. The most biodegradable form of EDDS, namely ⁵⁹Fe‐EDDS(S,S), provided ⁵⁹Fe for lettuce as efficiently as the mixture of ⁵⁹Fe‐EDDS stereoisomers and the ⁵⁹Fe‐EDTA. Utilization of ⁵⁹Fe in inorganic form was 0.5% and 0.03% in unlimed and limed sand, respectively. This study shows that biodegradable ligands are able to serve as chelators to sustain Fe availability in calcareous environments. They may be of use especially in drip irrigation, where ligand accumulations may pose a threat to groundwater quality.