The effect of oxygen deficiency on uptake and distribution of nutrients in maize plants |
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Authors: | B J Atwell B T Steer |
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Institution: | (1) School of Biological Sciences, Macquarie University, 2109 North Ryde, NSW, Australia;(2) Tropical Crops Research Group, School of Agriculture, The University of Western Australia, 6009 Nedlands, WA, Australia |
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Abstract: | Young maize (Zea mays L.) plants, 7 days after germination were exposed to nutrient solutions which were either aerated or not aerated for 14 days.
Nutrients were supplied as 50% strength Hoagland’s solution or, in the case of the four ‘low nutrient’ treatments, N, P, K
or Ca were supplied at the equivalent of 10% strength Hoagland’s solution.
Shoot fresh weight was decreased by 25% due to lack of aeration; O2 deficiency also impaired leaf elongation but not dry weights, suggesting that lack of O2 in the roots impaired cell expansion in shoots more than dry weight accumulation.
The distribution of N, P, K and Ca within shoots was consistent with their relative mobilities in the phloem; at least 7%
of Ca in plants after 14 days of treatments was found in the oldest leaf whereas N, P and K were rapidly remobilised to younger
tissues. Between 33 and 49% of the total N, P and K in the shoot was found in the 40 mm of tissue at the base of the growing
leaves in plants grown for 14 days at low nutrient concentrations. Concentrations (dry weight basis) of phloem-mobile nutrients
were also greatest in the growing zones of the leaves, especially in the case of N and P. Calcium, on the other hand, was
found in relatively low concentrations in the youngest tissue and as with the other nutrients, concentrations declined due
to low external supply, non-aeration or a combination of both.
In spite of the failure of Ca to move from old to young leaves, the effect of the deficiencies of N, P and K was probably
as severe as that of Ca in the youngest tissues of treated plants. Calcium uptake by the whole shoot appeared to be slightly
less sensitive to O2 deficits than that of N, P and K. This compensated for the failure of Ca to move to growing tissues during periods of low
external Ca supply. |
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Keywords: | aeration ion uptake oxygen roots Zea mays L |
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