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CROP PHYSIOLOGY & METABOLISM

Mineral Nutrition of Tomato under Diurnal Temperature Variation of Root and Shoot

^a Dep. of Forestry and Horticulture, Connecticut Agric. Exp. Stn., New Haven, CT 06504-1106 USA
^b Yale Univ., New Haven, CT 06520 USA

martin.gent{at}po.state.ct.us

	ABSTRACT

TOP NOTES ABSTRACT INTRODUCTION Materials and methods Results Discussion REFERENCES

 
Should root and shoot temperature vary in synchrony to optimize nutrient uptake, particularly when there is a large difference in temperature from day to night (DIF) of air and soil? To answer this question, tomato (Lycopersicon esculentum Mill.) seedlings were grown in greenhouses with the air heated to give either a +14°C DIF or a +5°C DIF in air temperature with a 16°C mean. The root medium was either unheated except by the air, or heated to 21°C constantly, only in the day, or only in the night. Experiments were repeated in early March and April in two years. Overall, growth was faster and there were higher concentrations of elements in leaves under +5°C compared with +14°C air DIF. Root-zone heating significantly increased growth and nutrition, compared with no heating. There was a trend in growth and nutrient concentration with timing of root heating: constant > day > night. These differences in growth and nutrition were similar under a +5°C or +14°C air DIF, and they were slight compared with no root-zone heating. For most nutrients, coordination of root and shoot activity related to uptake and metabolism did not require synchronous variation of air and soil temperature. Uptake and transport of nitrate was an exception. Heating roots in the day resulted in the highest nitrate concentration in leaves under a +14°C air DIF, whereas heating constantly was optimal under a +5°C DIF. Our results indicate nitrate metabolism did benefit from synchronous variation in air and root temperature.

Abbreviations: DIF, difference between day and night temperature

	INTRODUCTION

TOP NOTES ABSTRACT INTRODUCTION Materials and methods Results Discussion REFERENCES

 
ALTHOUGH GROWTH AND DEVELOPMENT of tomato responds primarily to temperature averaged over 24 h, the effect of the difference in temperature from day to night (DIF) cannot be ignored (Wolf et al., 1986). In a greenhouse in the northeast USA, a difference in temperature from day to night of +9°C compared with +4°C increased dry matter of tomato seedlings in winter but not in spring (Gent, 1984). A DIF of +14°C compared with +5°C in early spring increased the yield and fruit size of greenhouse tomatoes ripening in late spring and summer (Gent and Ma, 1998). In Holland, the primary effect on greenhouse tomato of a +4°C air DIF compared with a 0 to +1°C DIF was increased stem elongation (de Koning, 1988). Increased stem elongation is the most obvious physiological response of floricultural crops to a positive DIF (Erwin and Heins, 1995). Few studies have examined the effect of DIF on metabolism or plant nutrition. A positive DIF may lead to greater dry matter accumulation due to less respiration at night and increased non-structural carbohydrate (Gent and Enoch, 1983). Erwin and Heins (1995) cited studies in which increasing air DIF lowered Ca and Mg in leaves of Euphorbia, but increased chlorophyll per unit leaf weight in Chrysanthemum. Soybean [Glycine max (L.) Merr.] grown under 16 or 24°C at night more completely remobilized nitrogen during seed filling than when grown under 10°C at night (Seddigh and Jolliffe, 1986).

Field crops experience a large positive DIF in air temperature. Sadler and Schroll (1997) discuss these diurnal temperature patterns. Particularly in early spring, this DIF is associated with nights cooler than 15°C, a temperature critical for growth of tomato and other chilling-sensitive species. The root-zone temperature is not in synchrony with air temperature because of the large heat capacity of the root medium. In the field, the minimum and maximum temperature of the soil lags behind air temperature by about 2 h at a 10-cm depth and 8 h at 20 cm (Parton and Logan, 1981). Thus under field conditions, roots are cool and may metabolize slowly in the morning if the air is cool at night.

A root-zone temperature cooler than 15°C dramatically slows the uptake of mineral elements in the shoot of tomato, even if the shoot is warm (Cannell et al., 1963; Cornillon, 1974), and it has an equally dramatic effect on growth (Martin and Wilcox, 1963). Constantly heating roots to 16 to 18°C increases shoot dry weight if the air is cool at night (Gosselin and Trudel, 1983a; Shedlosky and White, 1987). Heating the root zone to 24°C increases phosphorus and potassium concentrations in the shoot of tomato grown under a 12 or 15°C night temperature, but the effect of heating roots is much less at air temperatures of 21°C or above (Gosselin and Trudel, 1983b). Under controlled conditions with a forced transition in air and root temperature from night to day, roots that are cool only in the night inhibit shoot growth far less than roots that are cool constantly or only in the day (Harssema, 1977; Ali et al., 1994). Under a large DIF in air temperature, it may be critical for root-zone temperature to vary in synchrony with air temperature, as more of the metabolism in the shoot would occur in the day.

Previous studies of DIF did not control air and root temperature independently (Gent, 1984; de Koning, 1988; Erwin and Heins, 1995). We hypothesize that the temperature of air and root zone must vary in phase for plant growth to show the most benefit from a positive DIF. To examine this point, we measured growth and concentration of mineral nutrients in tomato seedlings grown in greenhouses with heating regimes that independently varied the temperature of air and soil from day to night.

	Materials and methods

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Growth Conditions
The experiment was conducted in greenhouses with a double glazing of 0.1-mm clear polyethylene film. The air was heated by a forced-air heater, and horizontal air flow equalized temperature throughout each house. In two houses, the minimum air temperature was 22/6°C day/night, based on a 12-h day/night cycle with transitions at 0600 and 1800 h. Ventilation cooled the air when it was warmer than 28°C. In the other two houses, the minimum air temperature was 14°C both day and night. Ventilation commenced at 22°C. The two air temperature regimes are referred to as +14°C DIF and +5°C DIF, respectively. There were four troughs in each greenhouse, 0.3 by 0.3 m in cross section, lined with black polyethylene film supported by a wood and wire framework and insulated from the ground with 2-cm foil-backed polystyrene. These troughs were filled with a peat-vermiculite medium (Pro-Mix BX, Premier Brands, New Rochelle, NY) that was heated to a minimum temperature of 21°C by circulation of 40°C water through a loop of polybutylene rubber tubing. The timing of heating was different for three troughs. The 21°C minimum temperature was maintained over 24 h constantly, or for 6 h from 0500 to 1100 h in the day, or from 1700 to 2300 h in the night. The fourth trough was not heated.

Shaded copper-constantan thermocouples measured the air temperature at a height of 1.5 m in the center of each greenhouse. Thermocouples immersed in sand and insulated in 15-mm glass tubes measured the root-zone temperature at a depth of 10 cm in the center of each trough. The air temperature and humidity in each greenhouse was also measured with electronic sensors (Omega HX93V, Omega Engineering, Stamford, CT). These sensors were read every minute by a data logger (Campbell Scientific CR10, Logan, UT), and averaged hourly and recorded. These recordings were used to calculate day and night temperatures, and the difference in mean temperature between the day and the following night (DIF). The day and night temperatures and DIF were averaged over each 2-wk growth interval.

Plant Material
The greenhouse tomato cultivars Buffalo and Caruso (Stokes Seed Co., Buffalo, NY) were germinated and grown in pots in a growth chamber and in a greenhouse for 8 wk. For the final week, they were acclimated to a 10°C temperature at night. Seedlings were transplanted into the experimental greenhouses on 4 Mar and 25 Mar 1994, and on 1 Mar and 29 Mar 1995. Before transplanting, the root medium was flushed with excess water, and powdered Dolomitic limestone was incorporated to adjust pH to 6.0. Plants were transplanted so the root ball was between the heating tubes, with 0.3 m between plants along the trough. Plants were watered automatically each day at 0800 h with a complete nutrient solution containing 20:4:16 N:P:K at 50 mg N L^-1 (Peat-lite special, WR Grace and Co., Cambridge, MA).

The plants were grown for 10 to 14 d after transplanting until they reached a size suitable for sampling. Plants were harvested between 1100 and 1200 h. Two plants were harvested from each sub-plot by removal of the entire root ball. The roots were washed clean in cold running water. The plants were put in paper bags, frozen on dry ice, and freeze dried. The dried plants were separated into roots, leaf blades, and stem with petioles. These parts were weighed, then ground to pass a 20-mesh sieve. Samples from the two replicate sub-plots were combined, and duplicate sub-samples of this four-plant sample were taken for nutrient analysis.

Nutrient Analysis
Elemental composition was determined in 250-mg samples of freeze-dried plant tissue that was digested in 4 mL of boiling H₂SO₄ to which 10 mL of H₂O₂ was added drop wise. The digested tissue was diluted with water to 100 mL. Colorimetric measurements assayed total nitrogen by Nessler reagent, and total phosphorus by molybdate reagent (Thomas et al., 1967). Other elements were determined by inductively coupled plasma spectrophotometry (Model Atomscan 16, Thermo Jarrell Ash, Franklin, MA). All values were expressed as a weight fraction on a dry weight basis.

Design and Analysis
The experimental design was a complete split-split-plot, with air DIF (greenhouses) as main plots, root heating (troughs) as sub-plots, and cultivar as sub-sub-plots. There were four greenhouses and four troughs in each house. All air heat x root heat x cultivar combinations were replicated in two greenhouses. In 1995, the locations corresponding to air DIF, cultivar, and planting were reversed compared with 1994, and troughs were randomly reassigned to root-heating regimes.

The data for both plantings in both years were combined for analysis. Analysis of variance revealed no significant interactions between year or planting and air or root-zone heating regime or cultivar. Year and planting were treated as block effects, and interactions with air and root-zone heating and cultivar were used as the source of error to determine the significance of the latter effects. Relative growth rates were calculated over the growth interval from transplant to harvest to normalize for different initial weights.

	Results

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Temperature of the Air and Root Zone
The difference in temperature from day to night (DIF) was +14 to +15°C, when the air was heated to a minimum of 22°C in the day and 6°C in the night. A +4 to +6°C air DIF resulted from a minimum temperature of 14°C both day and night (Table 1) . We refer to these two air-temperature regimes as +14°C and +5°C air DIF, respectively. While the air warmed up rapidly in the morning because of heating and solar radiation, and cooled rapidly at night, the temperature of the root zone changed gradually because of the large heat capacity of the root medium. Because the root zone heated slowly, and was cooled by watering in the morning, the mean temperature of the unheated root zone was cooler than that of the air. Despite a 8°C range in temperature, the DIF of unheated roots was generally <1°C, because temperature was out-of-phase with photo-period. Root-zone heating changed the root-zone DIF by at most +6°C or -3°C, by heating in the day only or in the night only, respectively. In part, the changes were small because the effect of heating the root zone lingered for several hours after the heating stopped. The air heating regimes had relatively little effect on the mean or DIF in root-zone temperature. Relative humidity was higher in the day and lower at night under +5°C compared with +14°C DIF. Averaged over all plantings, relative humidity was 0.77 and 0.72 in the day, and 0.86 and 0.97 at night, under +5°C and +14°C DIF, respectively. Daily integrated irradiance measured outside the greenhouse was similar in both years. It was 20% higher in April than March.

View larger version (67K): [in this window] [in a new window]   Fig. 1 Relative growth rate of tomato under +5°C or +14°C air DIF with the root zone heated constantly, in the day, in the night or not heated. Error bars indicate standard error of the estimate

View larger version (65K): [in this window] [in a new window]   Fig. 2 Total reduced nitrogen concentration in leaves of tomato grown under +5°C or +14°C air DIF with the root zone heated constantly, in the day, in the night, or not heated. Error bars indicate standard error of the estimate

View larger version (44K): [in this window] [in a new window]   Fig. 3 Nitrate concentration in leaves of tomato harvested under high or low light after growth under +5°C or +14°C DIF with the root zone heated constantly, in the day, in the night, or not heated. Error bars indicate standard error of the estimate

Effects of air or root-zone temperatures on concentrations of phosphorus, calcium, and manganese differed among the two cultivars (Table 2). Under +5°C air DIF, concentrations of these elements were highest with constant root-zone heating for Buffalo and with day heating for Caruso. Under +14°C DIF, Caruso had the highest concentrations with constant heating, and concentrations in Buffalo did not differ among regimes with root-zone heating. In other studies, Nkansah and Ito (1995) found two tomato cultivars also differed in uptake of phosphorus and calcium, as well as potassium and magnesium, when grown under warm air temperature. However, six cultivars grown under cool air temperatures and low light showed no significant genotype x air temperature interactions in uptake of nitrogen or phosphorus (Van de Dijk, 1986).

According to Roorda van Eysinga and Smilde (1981), concentrations of most elements in leaves were within the healthy range, except potassium and calcium. These were below the values considered healthy, 28 to 60 and 24 to 72 mg g^-1, for potassium and calcium, respectively, but above the values considered to be deficient, 12 and 7 mg g^-1, respectively. Nitrate was always below the value considered deficient, 1 mg N g^-1, except for the harvest in April 1995, because we harvested at noon, and the high irradiance lowered the nitrate in leaves.

Nutrients in Stem and Petioles
Compared with leaves, stems had less total reduced nitrogen and calcium, 27 and 37 mg g^-1, respectively, and more potassium and nitrate-N, 64 and 3.7 mg g^-1, respectively. The response to air DIF of total nitrogen, phosphorus and calcium in stem and petioles was similar to that in leaves. The potassium in stems was higher under +5°C compared with +14°C DIF, 60 and 68 mg g^-1 respectively. The effects of root-zone heating on stem composition were similar to those in leaves. Stems contained more nitrate under constant or day heating, 4.1 and 4.5 mg N g^-1, respectively, than under night heating or no root-zone heat, 3.4 and 2.6 mg N g^-1, respectively. Although there were more amino acids in stems than leaves, only constant root-zone heating increased the amino acid concentration in stems compared with no root-zone heating, 4.6 compared with 4.2 mg N g^-1, respectively.

Nutrients in Roots
In general, the response to air and root-zone temperature of nitrogen concentration in roots was opposite to that in leaves (Compare Fig. 2 and 4) . Roots of plants grown under +14°C DIF had more nitrogen than those grown under +5°C DIF, and unheated roots and those heated in the night had significantly more nitrogen than those heated in the day or constantly (Table 3) . The amino acid concentration changed in the same direction as total reduced nitrogen, but nitrate in roots did not respond to air or root-zone DIF. Effects of root-zone heating differed among the two cultivars; unheated roots of Buffalo had 3 mg g^-1 more nitrogen than those of Caruso, while roots heated at night had 2 mg g^-1 less.

View larger version (58K): [in this window] [in a new window]   Fig. 4 Total reduced nitrogen concentration in roots of tomato grown under +5°C or +14°C air DIF with the root zone heated constantly, in the day, in the night, or not heated. Error bars indicate standard error of the estimate

Nutrient Uptake Rates
Relative nutrient uptake rates on a whole plant basis were calculated from initial and final plant weights and elemental concentrations. Because a greater air DIF slowed growth, it also slowed nutrient uptake rates, even when it had relatively little effect on elemental concentrations. Root-zone heating affected both growth and elemental concentrations, and had greater effects than air DIF on relative nutrient uptake rates. Overall, nitrogen relative uptake rates for regimes with root-zone heating averaged 3.0 mg N g^-1 d^-1 compared with 2.1 mg N g^-1 d^-1 with no heat. Nitrogen uptake rates varied with timing of root-zone heating under a +14°C air DIF more than under a +5°C DIF. Under +14°C air DIF, the uptake rates were 3.3, 2.9 and 2.4 mg N g^-1 d^-1, for constant, day and night heating, respectively, while under +5°C DIF these rates were 3.2, 3.4 and 3.1 mg N g^-1 d^-1, respectively.

Carbohydrate
Plants had more starch when grown under +14°C compared with +5°C air DIF, and with unheated compared with heated roots (Tables 2 and 3). The differences due to root-zone heating were greater in plants grown under +5°C compared with +14°C air DIF (data not shown). When starch increased in leaves in response to air or root-zone temperature, it also increased in roots.

There were differences among harvest dates in concentration of most nutrients (Tables 2 and 3, Fig. 2 through 4). These were due to differences in light, mean temperature and growth rates. The concentration of all mineral elements, except phosphorus, were low in leaves when plants grew quickly or had a high starch concentration. There was no interaction between effects of harvest date and the temperature treatments.

	Discussion

TOP NOTES ABSTRACT INTRODUCTION Materials and methods Results Discussion REFERENCES

 
We hypothesized that the temperature of air and root zone must vary in phase for plant growth to show the most benefit from a positive DIF. In fact, differences in growth due to the timing of root-zone heating were small compared with the difference due to not heating. The rankings for growth rates and nutrient concentrations in leaves were the same as the ranking in mean temperatures of the root zone, namely constant > day > night. Growth and leaf nutrient concentrations of tomato are very sensitive to a change in root temperature around 15°C (Cannell et al., 1963; Martin and Wilcox, 1963), and growth and nutrient uptake of tomato increase with temperature up to 24–27°C (Ganmore-Neumann and Kafkafi, 1980; Gosselin and Trudel, 1983a, b; Tindall et al., 1990; Nkansah and Ito, 1995). The effect of timing of root-zone heating that we observed here may be due to an altered mean temperature rather than root-zone DIF. The timing of root-zone heating may not be critical because root-zone DIF was not as large as air DIF. Without forced cooling, the root-zone temperature can not change as rapidly as that of the air, due to the large heat capacity of the root medium.

Tomato seedlings grew more slowly under +14°C than +5°C air DIF, except when the root-zone was heated constantly. Various species of flowers and vegetables benefitted from constant root-zone heating when air was cool at night (Shedlosky and White, 1987). The seedlings grew at similar rates under 7°C or 16°C air temperature at night, when the roots were heated constantly to 16°C. Leaf area expansion of potato (Solanum tuberosum L.) had an optimum DIF that increased with day temperature, from a DIF of 0°C with days at 20°C, to a DIF of +11°C with days at 35°C (Benoit et al., 1986). The +14°C air DIF in our study may be deleterious because it was combined with a relatively cool mean temperature.

The tomato leaves had lower concentrations of most mineral elements when grown under +14°C DIF compared with +5°C DIF. In studies which compared cool nights to warm nights under a similar day temperature, the positive DIF increased the concentration of most elements in tomato leaves (Gosselin and Trudel, 1983b; Papadopoulos and Tiessen, 1987). This was attributed to slower growth, and less dilution of nutrients by dry matter accumulation when the mean air temperature was lowered by cool nights. A positive DIF increases starch and nonstructural carbohydrate in tomato leaves (Gent, 1984). An increase in starch also dilutes nutrient concentrations. The growth rate and starch dilution factors appeared to cancel out in the current study; the +14°C air DIF increased starch by 8% and decreased relative growth rate by 6%. After taking these factors into account, the uptake of nutrients was less under +14°C than +5°C air DIF.

Heating roots at any time in the diurnal cycle increased uptake of minerals compared with no heating, and heating constantly resulted in the highest concentration for most elements in leaves under either +5°C or +14°C air DIF. The concentration of nitrate in leaves was an exception. Under +5°C DIF, the concentration of nitrate in leaves was highest with constant root heating, but under +14°C DIF it was highest with roots heated in the day (Fig. 3). The concentrations of nitrate, and other forms of nitrogen, decreased in leaves and increased in roots in response to cool root temperature. This effect was not seen for any other element, as noted by Cornillon (1974). Nitrate uptake was affected by both air and root temperature, in contrast to phosphate uptake which was affected only by root temperature (Cornillon and Maisonneuve, 1985). Heating tomato roots to 27°C under cool air at night increased phosphorus but not nitrogen (Papadopoulos and Tiessen, 1987). We found the leaf concentration of nitrate was more sensitive to root temperature than that of total reduced nitrogen, as noted by Ganmore-Neumann and Kafkafi (1980). These facts suggest cool temperature inhibited translocation of nitrate from roots to leaves more than it inhibited uptake of nitrate into the roots. In experiments with maize (Zea mays L.) (Engels et al., 1992) the temperature of the shoot base controlled translocation of nitrate. Even when roots were cool, if the shoot base was warm, roots took up and translocated nitrate to the shoot. They noted that cool temperature inhibited uptake of phosphate into the roots regardless of the temperature of the shoot base.

The diurnal variation of air and soil temperature may play a role in nitrogen nutrition of field crops. Nitrate is the primary form of nitrogen taken up by tomato and other crops. In spring, the soil temperature is often cool, and soil warms more slowly than the air, both over a diurnal cycle and over the season. Nitrogen deficiency has long been recognized as a consequence of cool soils. Our results show that more rapid warming of soil in the morning improves nitrate uptake and transport to the shoot. Nitrate uptake to leaves should benefit from the use of clear or black plastic mulch to concentrate heat from solar radiation in the soil during the day, even if daily average soil temperature does not rise significantly.

In summary, for most mineral elements, synchronous variation of root-zone and air temperature was not critical for uptake by roots or assimilation in the shoot. Tomato plant growth, and nutrient concentrations in leaves, had similar responses to the timing of root-zone heating under a small or large diurnal variation in air temperature. Nitrate concentrations in leaves were most sensitive to the timing of root-zone heating, more so than total reduced nitrogen. Nitrogen metabolism in the plant must accommodate, in part, to the low concentration of nitrate induced by out-of-phase variation in temperature of the root and shoot.

	NOTES

TOP NOTES ABSTRACT INTRODUCTION Materials and methods Results Discussion REFERENCES

 
Approved by the director of the Connecticut Agric. Exp. Stn. Research supported in part by grant 93-37100-9101 from NRI Competitive grants program/USDA.

Received for publication November 15, 1999.

	REFERENCES

TOP NOTES ABSTRACT INTRODUCTION Materials and methods Results Discussion REFERENCES

 

• Ali I.A., Kafkafi U., Sugimioto Y., Inanaga S. Response of sand grown tomato supplied with varying ratios of nitrate/ammonium to constant and variable root temperatures. J. Plant Nutr. 1994;17:2001-2024.
• Benoit G.R., Grant W.J., Devine O.J. Potato top growth as influenced by day-night temperature differences. Agron. J. 1986;78:264-269.[Abstract/Free Full Text]
• Cannell G.H., Bingham F.T., Lingle J.C., Garber M.J. Yield and nutrient composition of tomatoes in relation to soil temperature, moisture and phosphorous levels. Soil Sci. Soc. Proc. 1963;27:560-565.
• Cornillon P. Behavior of the tomato in terms of substrate temperature. Ann. Agronomie 1974;25:753-777.
• Cornillon P., Maisonneuve B. Effect of low air and root temperatures on plant nutrition and pollen fertility in tomato. Agronomie 1985;5:33-38.
• de Koning A.N.M. The effect of different day/night temperature regimens on growth, development and yield of glasshouse tomatoes. J. Hortic. Sci. 1988;63:465-471.
• Engels C., Munckle L., Marschner H. Effect of root zone temperature and shoot demand on uptake and xylem transport of macronutrients in maize. J. Exp. Bot. 1992;43:537-547.[Abstract/Free Full Text]
• Erwin J.E., Heins R.D. Thermomorphogenic responses in stem and leaf development. HortScience 1995;30:940-949.[Free Full Text]
• Ganmore-Neumann R., Kafkafi U. Root temperature and percentage effect on tomato development II. Nutrient composition of tomato plants. Agron. J. 1980;72:762-766.[Abstract/Free Full Text]
• Gent M.P.N., Enoch H.Z. Temperature dependence of vegetative growth and dark respiration: A mathematical model. Plant Physiol. 1983;71:562-567.[Abstract/Free Full Text]
• Gent M.P.N. Carbohydrate level and growth of tomato plants: Effect of carbon dioxide enrichment and diurnally fluctuating temperatures. Plant Physiol. 1984;76:694-699.[Abstract/Free Full Text]
• Gent M.P.N., Ma Y.-Z. Diurnal temperature variation of the root and shoot affects yield of greenhouse tomato. HortScience 1998;33:47-51.[Abstract/Free Full Text]
• Gosselin A., Trudel M.J. Interactions between air and root temperatures on greenhouse tomato: I. Growth, development and yield. J. Am. Soc. Hort. Sci. 1983;108:901-905 a.
• Gosselin A., Trudel M.J. Interactions between air and root temperatures on greenhouse tomato: II. Mineral composition of plants. J. Am. Soc. Hort. Sci. 1983;108:905-909 b.
• Harssema H. Root temperature and growth of young tomato plants. Meded. Landbou. Wageningen 1977;77-19:52-61.
• Martin G.C., Wilcox G.E. Critical soil temperature for tomato plant growth. Soil Sci. Soc. Am. Proc. 1963;27:565-567.
• Nkansah G.O., Ito T. Comparison of mineral absorption and nutrient composition of heat-tolerant and non heat-tolerant tomato plants at different root-zone temperatures. J. Hortic. Sci. 1995;70:453-460.
• Papadopoulos A.P., Tiessen H. Root and air temperature effects on elemental composition of tomato. J. Am. Soc. Hort. Sci. 1987;112:988-993.
• Parton W.J., Logan J.E. A model for diurnal variation in soil and air temperature. Agric. For. Meteorol. 1981;23:205-216.
• Roorda van Eysinga J.P.N., Smilde K.W. Nutritional disorders of glasshouse tomatoes, cucumbers and lettuce. Wageningen, Netherlands: P. U. D. O. C, 1981.
• Sadler E.J., Schroll R.E. An empirical model for diurnal temperature patterns. Agron. J. 1997;89:542-548.[Abstract/Free Full Text]
• Seddigh M., Jolliffe G.D. Remobilization patterns of C and N in soybeans with different sink-source ratios induced by various night temperatures. Plant Physiol. 1986;81:136-141.[Abstract/Free Full Text]
• Shedlosky M.E., White J.W. Growth of bedding plants in response to root-zone heating and night temperature regimes. J. Am. Soc. Hort. Sci. 1987;112:290-295.
• Thomas R.L., Sheard R.W., Moyer J.R. Comparison of conventional and automated procedures for nitrogen, phosphorus, and potassium analysis of plant material using a single digestion. Agron. J. 1967;59:240-243.[Abstract/Free Full Text]
• Tindall J.A., Mills H.A., Radcliffe D.E. The effect of root-zone temperature on nutrient uptake of tomato. J. Plant Nutr. 1990;13:839-856.
• Van de Dijk S.J. Differences between genotypes of tomato in foliar contents of total phosphorus, total nitrogen and nitrate nitrogen under low light intensity and low night temperatures. Neth. J. Agric. Sci. 1986;34:49-59.
• Wolf S., Rudich J., Marani A., Rekah Y. Predicting harvest date of processing tomatoes by a simulation model. J. Am. Soc. Hort. Sci. 1986;111:11-16.

This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Gent, M. P.N. Articles by Ma, Y.-Z. Search for Related Content PubMed Articles by Gent, M. P.N. Articles by Ma, Y.-Z. Agricola Articles by Gent, M. P.N. Articles by Ma, Y.-Z.