Effects of nitrogen availability and supplementary light on the nitrate content of soil-grown lettuce

McCall, Douglas; Willumsen, J.

doi:10.1080/14620316.1999.11511137

Cited by 29 publications

(20 citation statements)

References 2 publications

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“…Ammonium-fed plants accumulated less NO 3 -and more Cl -than nitrate-fed plants ( Table V). The negative correlation between the nitrate and chloride ion contents has been reported by several authors (Behr and Wiebe, 1989;McCall and Willumsen, 1999). When plants accumulate less NO 3 -, a decrease in the osmotic values of vacuoles is prevented mainly by increasing Cl -ions and organic-N compounds (van der Boon et al, 1990).…”

Section: Discussionmentioning

confidence: 86%

Effects of ammonium and nitrate nutrition on yield and quality in endive

Bonasia

Conversa

Gonnella³

et al. 2008

The Journal of Horticultural Science and Biotechnology

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We have investigated the effect of 8 mM NH 4 -N and 8 mM NO 3 -N nutrient solutions on two cultivars ('Pancalieri Castello' and 'Nepal') of endive (Chicorium endivia L. var. crispum Hegi) grown using the nutrient film technique. Growth (leaf number and area), yield (head fresh mass), quality (dry matter, colour, and nitrate content of leaves), and some chemical and physiological characteristics were evaluated (e.g., total Kjeldahl nitrogen, inorganic ion and chlorophyll contents, SPAD index, osmotic potential, and membrane permeability). Endive yield (230 g plant -1 , on average) was not suppressed by ammonium nutrition. No symptoms of ammonium toxicity were detected. Cation antagonism did not occur. The contents of chlorophyll a and total chlorophyll in ammonium-fed plants increased, as did the SPAD index (39.2 in ammonium-fed plants vs. 30.6 in nitrate-fed plants). Membrane permeability and total osmotic potential were not altered. Independently from the form of N applied, differences in morphogenetic features between the cultivars emerged. 'Pancalieri Castello' produced heads characterised by higher weight, more expanded leaves, and with lower sugar content compared to 'Nepal'. From a commercial viewpoint, ammonium-fed plants had a marketable yield of a nitrate-free product, without damage from ammonium, or defects in morphological features.

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Section: Discussionmentioning

confidence: 86%

Effects of ammonium and nitrate nutrition on yield and quality in endive

Bonasia

Conversa

Gonnella³

et al. 2008

The Journal of Horticultural Science and Biotechnology

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“…However, because only one of these carboxyl anions replaces two ions of nitrate, such a change is insufficient to maintain a constant osmotic concentration, and is normally accompanied by changes in the concentrations of soluble carbohydrates. The latter are comprised largely of monosaccharides (such as glucose and fructose) and disaccharides (such as sucrose) in varying proportions (Blom-Zandstra and Lampe 1985;Behr and Wiebe 1988;McCall and Willumsen 1999). Recent evidence suggests that a combination of such mass and charge balance relationships are not only essential for isoosmotic regulation in plant sap, but can also play a key role in controlling the accumulation of nitrate in the shoots of individual lettuce cultivars (Burns et al 2011a).…”

Section: Discussionmentioning

confidence: 97%

“…This results from two key processes: concentration regulation (the substitution of alternative osmotica when others decline) and volume regulation (changes in the concentration of tissue water), both of which tend to reduce variations in the concentration of total solutes in plant sap (Wyn Jones and Gorham 1982;Nobel 2005). Thus while changes in environmental variables such as light level (Blom-Zandstra and Lampe 1985;Steingröver et al 1986;McCall and Willumsen 1999) and in the amount and form (ammonium vs nitrate) of N supplied (McCall and Willumsen 1998;Buwalda and Warmenhoven 1999;Burns et al 2011a) can markedly affect concentrations of nitrate in the sap of crops such as lettuce and spinach, corresponding variations in the concentrations of total solutes (and their associated osmotic potential) are much smaller.…”

Section: Discussionmentioning

confidence: 98%

The influence of genetic variation and nitrogen source on nitrate accumulation and iso-osmotic regulation by lettuce

Burns

Durnford

Lynn³

et al. 2011

Plant Soil

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Background and aims Characterisation of genetic variation in nitrate accumulation by lettuce will inform strategies for selecting low-nitrate varieties more capable of meeting EU legislation on harvested produce. This study uses a population of recombinant inbred lines (RILs) of lettuce to determine how genotypic differences influence N uptake, N assimilation and iso-osmotic regulation, and to identify key related traits prior to future genetic analysis. Methods Measurements were made on plants grown to maturity in soil fertilised with ammonium nitrate, and in a complete nutrient solution containing only nitrate-N. A simple osmotic balance model was developed to estimate variations in shoot osmotic concentration between RILs. Results There were significant genotypic variations in nitrate accumulation when plants were grown either with nitrate alone or in combination with ammonium. Ammonium-N significantly reduced nitrate in the shoot but had no effect on its relative variability, or on the ranking of genotypes. Shoot nitrate-N was correlated positively with total-N and tissue water, and negatively with assimilated-C in both experiments. Corresponding relationships with assimilated-N and shoot weight were weaker. Estimated concentrations of total osmotica in shoot sap were statistically identical in all RILs, despite variations in nitrate concentration across the population. Conclusions Approximately 73% of the genotypic variability in nitrate accumulation within the population of RILs arose from differences in nitrate uptake and only 27% from differences in nitrate assimilated, irrespective of whether or not part of the N was recovered as ammonium, or whether the plants were grown in soil or solution culture. Genotypic variability in nitrate accumulation was associated with changes in concentrations of other endogenous solutes (especially carboxylates and soluble carbohydrates) and of tissue water, which minimised differences in osmotic potential of shoot sap between RILs. This offers the opportunity of using the regulation of these solutes as additional traits to manipulate nitrate accumulation.

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“…Thus, senescence in upper leaves at 96 dps may well be induced by a lack of nutrients; P SAG12 -IPT is switched on, but is not autoregulated because of the shortage of nutrients. High concentrations of hexoses can be explained by the inverse relationship between nitrate and hexoses as osmoticum in plants ( BlomZandstra and Lampe, 1985;Pritchard et al, 1996;McCall and Willumsen, 1999). If nitrate concentrations are low due to a block of reallocation and uptake via the root system, this can be compensated by increasing concentrations of hexoses.…”

Section: Discussionmentioning

confidence: 99%

Effects of PSAG12-IPT Gene Expression on Development and Senescence in Transgenic Lettuce

McCabe¹

2001

Plant Physiology

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An ipt gene under control of the senescence-specific SAG12 promoter from Arabidopsis (P SAG12 -IPT) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (Lactuca sativa L. cv Evola) homozygous for the transgene. Apart from retardation of leaf senescence, mature, 60-d-old plants exhibited normal morphology with no significant differences in head diameter or fresh weight of leaves and roots. Induction of senescence by nitrogen starvation rapidly reduced total nitrogen, nitrate, and growth of transgenic and azygous (control) plants, but chlorophyll was retained in the lower (outer) leaves of transgenic plants. Harvested P SAG12 -IPT heads also retained chlorophyll in their lower leaves. During later development (bolting and preflowering) of transgenic plants, the decrease in chlorophyll, total protein, and Rubisco content in leaves was abolished, resulting in a uniform distribution of these components throughout the plants. Homozygous P SAG12 -IPT lettuce plants showed a slight delay in bolting (4-6 d), a severe delay in flowering (4-8 weeks), and premature senescence of their upper leaves. These changes correlated with significantly elevated concentrations of cytokinin and hexoses in the upper leaves of transgenic plants during later stages of development, implicating a relationship between cytokinin and hexose concentrations in senescence.Leaf senescence is a type of programmed cell death characterized by loss of chlorophyll, lipids, total protein, and RNA (Smart, 1994; Gan and Amasino, 1997). This process is believed to be an evolutionarily acquired, active genetic trait that contributes to plant fitness, for example, by remobilizing nutrients from vegetative tissues to reproductive organs (Oh et al., 1997). The biological importance and potential for improvement of crop characteristics, particularly plant productivity and postharvest storage, have prompted extensive physiological, molecular, and genetic analyses of leaf senescence (Nam, 1997). Senescence can be induced by environmental stress, such as low light intensity, nutrient deficiency, pathogen attack, drought, waterlogging, and detachment from the plant. Endogenous factors, including leaf age and reproductive development, also trigger senescence (Smart, 1994; Gan and Amasino, 1997).Plant growth regulators, including auxins, gibberellins, ethylene, abscisic acid, and cytokinins, are believed to play major roles in regulating senescence. Attention has focused on cytokinins that are key components of plant senescence (Van Staden et al., 1988;Singh et al., 1992;Gan and Amasino, 1996, 1997; Buchanan-Wollaston, 1997;Nam, 1997). These compounds have been implicated in several aspects of plant development and are thought to be synthesized mainly in the roots and transported to the shoots via the xylem (Gan and Amasino, 1996). Three main approaches have been used to study the effect of cytokinins in plant senecence, namely exogenous application of cytokinin solutions, measurement of endogenous cytokinins duri...

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Effects of nitrogen availability and supplementary light on the nitrate content of soil-grown lettuce

Cited by 29 publications

References 2 publications

Effects of ammonium and nitrate nutrition on yield and quality in endive

Effects of ammonium and nitrate nutrition on yield and quality in endive

The influence of genetic variation and nitrogen source on nitrate accumulation and iso-osmotic regulation by lettuce

Effects of PSAG12-IPT Gene Expression on Development and Senescence in Transgenic Lettuce

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