scholarly journals Effects of low light intensities at night on nitrate accumulation in lettuce grown on a recirculating nutrient solution

1993 ◽  
Vol 41 (1) ◽  
pp. 13-21
Author(s):  
E.G. Steingrover ◽  
J.W. Steenhuizen ◽  
J. Van Der Boon
Keyword(s):  
Nutrient Solution ◽  
Nitrate Concentration ◽  
Leafy Vegetables ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Negative Effects ◽  
Nitrate Accumulation ◽  
Light Intensities ◽  
Nutrient Film Technique ◽  
Nutrient Solutions

During winter, when light intensities are low, high nitrate concentrations often occur in leafy vegetables which are undesirable from the viewpoint of public health. The effects of low lighting during the night in combination with various nutrient solutions and solution temperatures on the nitrate concentration of lettuce cv. Panvit plants grown in a nutrient film technique system were studied. The experiment showed that lettuce heads could be grown during winter under glass with a nitrate concentration as low as 2900 mg/kg FW, which is much lower than the maximum permissible concentration for winter-grown lettuce in the Netherlands of 4500 mg/kg. The lowest nitrate concentration, without negative effects on yield or quality, was obtained by growing the crop on recirculating nutrient solutions with an initial ammonium:nitrate ratio of 0.25, with a change to a ratio of 1.0 for the last 2 weeks. The addition of chloride did not affect the nitrate concentration. Raising the temperature of the nutrient solution at night from 6 to 10 degrees C in combination with a minimum air temperature of 6 degrees stimulated growth, but also increased the lettuce nitrate concentration by an average of 360 mg/kg. Supplying light of a low intensity at a photon flux density of 27 micro mol m-2s-1 (400-700 nm) at night for up to 8 nights before harvest did not further reduce the nitrate concentration on a FW basis because the dry matter percentage increased.

scholarly journals Impact of Light Intensity and Nitrogen of Nutrient Solution on Nitrate Content in Three Lettuce Cultivars Prior to Harvest

2018 ◽  
Vol 10 (6) ◽  
pp. 99 ◽  
Author(s):  
Khurshid Ahmed Khan ◽  
Zhengnan Yan ◽  
Dongxian He
Keyword(s):  
Light Intensity ◽  
Nutrient Solution ◽  
Nitrogen Supply ◽  
Leafy Vegetables ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Nitrate Content ◽  
High Accumulation ◽  
Important Indicator ◽  
Fluorescent Lamps

Nitrate smoothly accumulates in leafy vegetables and poses serious health hazards if connected excessively in the human diet. The objective of this study was to improve the cultivation method of low nitrate lettuce grown in plant factory. A substantial decrease of nitrate content (NO3-) in three lettuce cultivars were subjected by short-term pre-harvest treatment combined with lowing nitrogen supply of nutrient solution to half concentration and high photosynthetic photon flux density (PPFD) by LED lighting. The lettuce (Lactuca sativa L. cv. Frill ice, Lvzhu, Ziwei) were hydroponically grown in full strength of nutrient solution based on Yamasaki formula up to harvest time within a controlled environment under two light sources using fluorescent lamps and LEDs. The results demonstrated that a subsequent 3-days treatment of additional PPFD from 250 µmol m-2 s-1 to 350 µmol m-2 s-1 from 18 days after transplanting and half concentrations of nitrogen (NO3--N) in nutrient solution which is composition to standard resulted in the decrease of nitrate content as compared to plants grown under initial PPFD and full concentration of NO3--Ncomposition. The gradual decrease in nitrate content was accompanied by an increased concentration of nutritionally carbohydrates. Another important indicator of nutritional quality such as vitamin C content exhibited some variation, fresh weight of cultivars in cv. Frill ice and Ziwei observed higher with fluorescent lamps and for cv. Lvzhu with LED treatment section followed by lowest nitrate content of fresh leaves, respectively. Further, presented results disclosed that to avoid high accumulation of nitrate in leafy vegetables, the strategy of lowering nitrogen supply and increasing light intensity prior to harvest benefiting growers and consumers by improving quality of the product also making it consumer friendly.

scholarly journals Decrease in Nitrate Concentration in Leafy Vegetables Under a Solid-state Illuminator

HortScience ◽  
2009 ◽  
Vol 44 (7) ◽  
pp. 1857-1860 ◽  
Author(s):  
Giedrė Samuolienė ◽  
Akvilė Urbonavičiūtė ◽  
Pavelas Duchovskis ◽  
Zenonas Bliznikas ◽  
Pranciškus Vitta ◽  
...  
Keyword(s):  
Solid State ◽  
Nitrate Concentration ◽  
Day Treatment ◽  
Substantial Reduction ◽  
Reduction Rate ◽  
Leaf Tissue ◽  
Leafy Vegetables ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Tissue Aging

We report on a substantial reduction of nitrate concentration in leafy vegetables that were subjected to short-term preharvest treatment by narrow-bandwidth red light of high photosynthetic photon flux density generated by a solid-state illuminator. Lettuce (Lactuca sativa cv. Grand rapids), marjoram (Majorana hortensis, Moench.), and green onions (Allium cepa, L. cv. Lietuvos didieji) were grown to harvest time within a greenhouse under daylight with supplementary lighting provided by standard high-pressure sodium lamps (130 μmol·m−2·s−1). A subsequent 3-day treatment within a phytotron under 638-nm light-emitting diodes (500 μmol·m−2·s−1) resulted in the reduction of nitrate concentration by 44% to 65%. The reduction of nitrates was accompanied by an increased concentration of nutritionally valuable carbohydrates, which is also in line with stimulation of expression of nitrate reductase by photosynthetic metabolites. Another indicator of nutritional quality, the content of vitamin C, exhibited some variation that was not directly correlated with the nitrate reduction rate that may be attributed to carbohydrate content variation and leaf tissue aging.

scholarly journals Nitrate concentration in lettuce leaves depending on photosynthetic photon flux and nitrate concentration in the nutrient solution

2011 ◽  
Vol 29 (4) ◽  
pp. 548-553 ◽  
Author(s):  
Nilton Nélio Cometti ◽  
Madlles Q Martins ◽  
Cintia Aparecida Bremenkamp ◽  
José Arcanjo Nunes
Keyword(s):  
Nutrient Solution ◽  
Nitrate Concentration ◽  
Nitrate Solution ◽  
Light Availability ◽  
Dry Mass ◽  
Photon Flux ◽  
The European Union ◽  
Photosynthetic Photon Flux ◽  
Nitrate Accumulation ◽  
Growing Period

The nitrate accumulation in plant tissues can occur due to low light availability. However, published studies have not linked nitrate accumulation to photosynthetic photon flux (PPF) measured during the growing period. This study aimed to evaluate the effect of the reduction of photosynthetic photon flux and the concentration of nitrate in the nutrient solution on agronomic characteristics and accumulation of nitrate in lettuce grown in hydroponics. The trial design was entirely randomized in a factorial scheme (4 x 2) with three repetitions, and four shading levels: 0, 30, 50, and 80% and two nitrate levels in nutrient solution: 5 and 10 mmol L-1. The dry matter production decreased directly and linearly with the reduction of light. The lowest level in nitrate solution also led to reduction in dry mass yield. The maximum accumulation of nitrate reached 966.3 mg kg-1 fresh mass, with PPF of 118 μmol/m²/s and 140 mg L-1 of N-NO3-1 (below the maximum levels recommended by the European Union), and the minimum of 200 mg kg-1 with PPF of 455 μmol/m²/s and 70 mg L-1 of N-NO3-1 in the nutrient solution. The reduction of nitrate in the nutrient solution from 140 to 70 mg L-1 led to the reduction of nitrate accumulation in shoots, but also caused a decrease in the production of phytomass of shoots, as well as reduced leaf area significantly.

scholarly journals Effect of Reduced Nitrogen and Supplemented Amino Acids Nutrient Solution on the Nutritional Quality of Baby Green and Red Lettuce Grown in a Floating System

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 922 ◽  
Author(s):  
Pavlos Tsouvaltzis ◽  
Dimitrios S. Kasampalis ◽  
Danai-Christina Aktsoglou ◽  
Nikolaos Barbayiannis ◽  
Anastasios S. Siomos
Keyword(s):  
Amino Acids ◽  
Nutrient Solution ◽  
Nutritional Quality ◽  
Mineral Nitrogen ◽  
Leafy Vegetables ◽  
Nitrate Accumulation ◽  
Nitrogen Reduction ◽  
Soluble Solid ◽  
Floating System

Excessive nitrogen fertilization results in nitrate accumulation in leafy vegetables. Reducing the dose of mineral nitrogen or using alternate fertilizers lowers the nitrate accumulation; however, a critical minimum level of mineral nitrogen is necessary to maintain yield and nutritional quality. The aim of this study was to evaluate the effect of two levels of mineral nitrogen (100% and 50%) and three levels of an amino acid solution (0, 0.3, and 0.9%) in the nutrient solution of two baby lettuce cultivars (green and red) grown in a floating system. Nitrogen reduction did not affect yield (12.9–13.4 and 11.0–11.3 g/plant, respectively) but reduced nitrate accumulation (by 43 and 19%, respectively) in both green and red lettuce, while enhancing phenolic content (by 28%) and antioxidant capacity (by 69%) in green lettuce and soluble solid (by 7%) and total chlorophyll content (by 9%) in red lettuce. Although nitrate accumulation was prevented (< 355 mg/kg FW) and most nutritional components increased in both lettuce types by amino acids supplementation, plant growth was negatively affected, especially in red lettuce, in both concentrations of amino acids (reduction by 9 and 35% in 0.3 and 0.9%, respectively). In both lettuce types, proline content increased by 0.9% amino acids supplementation (by 45%), implying a probable induction of a stress condition. Mineral nutrients were slightly affected by nitrogen reduction, which was probably perceived as an abiotic stress.

Seasonal photosynthetic performance of Nereocystis luetkeana

1984 ◽  
Vol 62 (4) ◽  
pp. 664-670 ◽  
Author(s):  
W. N. Wheeler ◽  
R. G. Smith ◽  
L. M. Srivastava
Keyword(s):  
Flux Density ◽  
Late Summer ◽  
Photosynthetic Performance ◽  
Initial Slope ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Rates ◽  
Chl A ◽  
Light Intensities ◽  
Nereocystis Luetkeana

Pigment levels, photosynthetic performance, and tissue nitrogen levels of three age-class blade disks of Nereocystis luetkeana were followed over one complete and two partial growth seasons. Chlorophyll (chl) a, fucoxanthin, and chlorophyll c all showed high levels in fall–winter and low levels in late summer. The molar ratios also varied with much higher fucoxanthin: chl a and chl c: chl a ratios in early spring than in late summer–fall. Plots of maximum photosynthetic rates (Pmax) at saturating light intensities and initial slopes (α) derived from photosynthetic rates at subsaturating light intensities also showed seasonal variations, with maxima in August and September and minima in April. The saturating light irradiance, IR, also showed a maximum in late summer and a minimum in winter. Tissue nitrate levels were high in winter, declined to near zero levels in May–August, and increased again in fall–winter. Amino acids and total N followed a similar pattern. The older tissues farthest from the bulb had higher Pmax and pigment levels as well as internal nitrate levels than young proximal tissues. Environmental data on sea-water nitrate, photon flux density, and temperature and data on mannitol and total C are presented. It appears that there is a significant negative correlation between photon flux density and initial slope of photosynthesis and between Pmax and temperature below 15 °C. At temperatures above 15 °C, internal N concentrations, which in turn are governed by the ambient nitrate concentration, appear to become limiting. Pigment levels, especially chlorophyll a, showed a direct correlation with ambient nitrate. These data are discussed in relation to the possible biennial nature and growth strategy of Nereocystis.

scholarly journals Growth and Photosynthetic Capability of Momordica grosvenori Plantlets Grown Photoautotrophically in Response to Light Intensity

HortScience ◽  
2009 ◽  
Vol 44 (3) ◽  
pp. 757-763 ◽  
Author(s):  
Meijun Zhang ◽  
Duanduan Zhao ◽  
Zengqiang Ma ◽  
Xuedong Li ◽  
Yulan Xiao
Keyword(s):  
Callus Formation ◽  
Dry Weight ◽  
Control Treatment ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Naphthaleneacetic Acid ◽  
Ms Medium ◽  
Light Intensities ◽  
Four Levels

Momordica grosvenori plantlets were cultured in vitro for 26 d on sucrose- and hormone-free Murashige and Skoog (MS) medium with four levels of photosynthetic photon flux density (PPFD), namely 25, 50, 100, or 200 μmol·m−2·s−1, and a CO2 concentration of 1000 μmol·mol−1 in the culture room [i.e., photoautotrophic micropropagation (PA) treatments]. The control treatment was a photomixotrophic culture using MS medium containing sucrose and NAA with a CO2 concentration of 400 μmol·mol−1 in the culture room and a PPFD of 25 μmol·m−2·s−1. Based on the results, a second experiment was conducted to investigate the effects of α-naphthaleneacetic acid (NAA) and sucrose on callus formation. For this, plantlets were grown in the absence and presence of either NAA or sucrose. Compared with the control, the PA plantlet had a well-developed rooting system, better shoot, greater chlorophyll content, and higher electron transport rate and the ex vitro survival percentage was increased by 31%. Both sucrose and NAA stimulated callus formation on the shoot bases of control plantlets, whereas calluses did not form on the plantlets grown in sucrose- and hormone-free medium. The stronger light intensities increased the fresh and dry weight of plantlets. A PPFD of 100 μmol·m−2·s−1 was more suitable for the growth of M. grosvenori plantlets. Therefore, photoautotrophic plantlets grown at high light intensities would be better suited to the intense irradiance found in sunlight.

scholarly journals Accumulation of Possible Potato Tuber-inducing Factor in Continuous-use Recirculating NFT sSystem

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 790B-790 ◽  
Author(s):  
R.M. Wheeler ◽  
G.W. Stutte ◽  
C.L. Mackowiak ◽  
N.C. Yorio ◽  
L.M. Ruffe
Keyword(s):  
Nutrient Solution ◽  
Shoot Growth ◽  
Continuous Production ◽  
Tuber Initiation ◽  
The Past ◽  
Nutrient Film Technique ◽  
Continuous Use ◽  
Water Filters ◽  
Nutrient Solutions ◽  
Over Time

Potatoes (Solanum tuberosum L.) have been grown successfully with a recirculating nutrient film technique (NFT) when a fresh nutrient solution is used for each planting. During the past year, we conducted two studies in which the same nutrient solution was used for successive plantings (EC and pH were maintained at 0.12 S·m–1 and 5.8). Results showed that successive plantings became prematurely induced (tubers initiating near 20 days after planting–DAP), causing stunted shoot growth and reduced yields per plant. When “old” nutrient solution from a continuous production system was regularly added to a newly started plant system maintained under a non-inductive environment (12-h photoperiod with night break of 6 h into dark), tubers formed on “old” nutrient solution plants (24 DAP), but not on “new” solution plants. When charcoal water filters were placed on the systems, plants grown on either “old” or “new” nutrient solutions showed no tuber initiation (plants harvested at 42 DAP). Results suggest that a tuber-inducing factor(s) emanating from the plants accumulates in the nutrient solution over time and that the factor(s) can be removed by charcoal absorption.

Relationships between flowering phenology and female reproductive success in the Japanese tree species Magnolia stellata

Botany ◽  
2008 ◽  
Vol 86 (3) ◽  
pp. 248-258 ◽  
Author(s):  
Suzuki Setsuko ◽  
Ichiro Tamaki ◽  
Kiyoshi Ishida ◽  
Nobuhiro Tomaru
Keyword(s):  
Reproductive Success ◽  
Flowering Phenology ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Negative Effects ◽  
Female Reproductive Success ◽  
Large Numbers ◽  
Male Phase

We have examined the earliness, duration, and amplitude of flowering genets in a Magnolia stellata (Sieb. et Zucc.) Maxim. population in relation to their size, environmental factors (temperature and light), and female reproductive success (ovule survival rate) over three consecutive years. Average flowering durations of individual flowers, genets, and the whole population in these 3 years were 10.2, 15.2, and 29.0 d, respectively. A bisexual phase (with both female and male phase flowers) in genets spanned 62.9% of the total flowering period, suggesting that geitonogamy can occur. The earliness, duration, and amplitude of flowering genets were all significantly correlated, indicating that genets flower early and long periods have high flowering amplitudes. The three parameters were also significantly correlated with the size of the genets (represented by the diameter at breast height of its thickest ramet) and relative photosynthetic photon flux density at the top of their crowns. Therefore, genets that are large and located in well-lit sites tend to have many flowers, and blossom both earlier and longer. Later-flowering genets have higher female reproductive success, probably because M. stellata is protogynous. Significantly positive correlation between flowering amplitude and female reproductive success suggests that large numbers of flowers increase the attractiveness of genets for pollinators, and this outweighs the negative effects of geitonogamy.

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