Effects of suboptimal root zone temperatures and shoot demand on net translocation of micronutrients from the roots to the shoot of maize |
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Authors: | C Engels H Marschner |
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Institution: | (1) Institute of Plant Nutrition, University Hohenheim, 70593 Stuttgart, Germany |
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Abstract: | The effects of suboptimal root zone temperatures (RZTs) on net translocation rates from the roots to the shoots and the concentrations
of Fe, Mn, Zn, and Cu were examined in maize grown in nutrient solution or soil. Plants were grown at 12 °C, 18 °C and 24
°C RZT. At each RZT, the growth-related shoot demand for nutrients was varied by independently modifying the temperature of
the shoot base (SBT) including the apical shoot meristem.
The net translocation rates of Mn and Zn from the roots to the shoots were reduced at low RZTs, irrespective of the SBT and
of the substrate (soil or nutrient solution). Obviously, the net translocation rates of Mn and Zn at low RZT were mainly regulated
by temperature effects on the roots and not by the chemical nutrient availability in the rhizosphere or by shoot growth rate
as controlled by SBTs. When both RZT and SBT were reduced, the decrease in net translocation rates of Mn and Zn was similar
to the decline in the shoot growth rate and concentrations of Mn and Zn in the shoot fresh matter were not greatly affected
or were even increased by low RZT. However, at high SBT and low RZT in nutrient solution, the depressed net translocation
rates of Mn and Zn combined with the increased shoot growth resulted in significantly decreased concentrations of Mn and Zn
in the shoot, indicating that Mn and Zn may become deficient even at high chemical availability.
By contrast to Mn and Zn, the net translocation rates of Fe and Cu at all RZTs were markedly enhanced by increased SBTs. Accordingly,
the concentrations of Fe and Cu in the shoot fresh matter were not greatly affected by RZTs, irrespective of the SBTs. These
results indicate that the ability of roots to supply Fe and Cu to the shoot was internally regulated by the growth related
shoot demand per unit of roots.
Deceased 21 September 1996
Deceased 21 September 1996 |
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Keywords: | maize net translocation rate micronutrient root zone temperature shoot base temperature shoot demand |
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