Kinetin application to roots and its effect on uptake, translocation and distribution of nitrogen in wheat (Triticum aestivum) grown with a split root system

Richard J. Simpson, Hans Lambers, Michael J. Dalling

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The root systems of wheat seedlings (Triticum aestivum L. cv. SUN 9E) were pruned to two seminal roots. One of the roots was supplied with a suboptimal level of NO3, the other was deprived of N. Different levels of kinetin were supplied to the NO3‐deprived roots. Root respiration and the increment of C and N in the roots were measured to determine the C/N ratio of the phloem sap feeding the NO3‐deprived roots. Thus, it was possible to determine retranslocation of N from the shoots to the roots, as affected by the rate of kinetin application. It was calculated that the C/N ratio of phloem sap feeding roots growing without kinetin was ca 61. Kinetin application increased this ratio to ca 75, partly due to decreased translocation of N from the shoots back to the roots. Kinetin application decreased the proportion of N that was retranslocated to the roots after translocation to the shoots. Kinetin increased the rate of NO3 uptake per root and the rate of N incorporation in both roots and shoots by ca 60%, but had no effect on shoot dry matter production. In control plants at most 70% of the N incorporated in the NO3‐fed roots could have been imported from the shoots, whilst kinetin application reduced this value to ca 40%. Thus root growth was not fully dependent on a supply of N via the phloem. It is concluded that cytokinins affect the pattern of N‐translocation in wheat plants by increasing incorporation of N in dry matter of the shoot, thus leaving less for export. Cytokinins did not play a major role in the regulation of shoot growth and the shoot to root ratio of the present plants.

Original languageEnglish
Pages (from-to)430-435
Number of pages6
JournalPhysiologia Plantarum
Volume56
Issue number4
DOIs
Publication statusPublished - 1 Jan 1982
Externally publishedYes

Fingerprint

Kinetin
kinetin
Triticum
root systems
Nitrogen
Triticum aestivum
uptake mechanisms
wheat
Phloem
nitrogen
shoots
Cytokinins
phloem
Growth
sap
carbon nitrogen ratio
Seedlings
cytokinins
Respiration
root shoot ratio

Cite this

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title = "Kinetin application to roots and its effect on uptake, translocation and distribution of nitrogen in wheat (Triticum aestivum) grown with a split root system",
abstract = "The root systems of wheat seedlings (Triticum aestivum L. cv. SUN 9E) were pruned to two seminal roots. One of the roots was supplied with a suboptimal level of NO3, the other was deprived of N. Different levels of kinetin were supplied to the NO3‐deprived roots. Root respiration and the increment of C and N in the roots were measured to determine the C/N ratio of the phloem sap feeding the NO3‐deprived roots. Thus, it was possible to determine retranslocation of N from the shoots to the roots, as affected by the rate of kinetin application. It was calculated that the C/N ratio of phloem sap feeding roots growing without kinetin was ca 61. Kinetin application increased this ratio to ca 75, partly due to decreased translocation of N from the shoots back to the roots. Kinetin application decreased the proportion of N that was retranslocated to the roots after translocation to the shoots. Kinetin increased the rate of NO3 uptake per root and the rate of N incorporation in both roots and shoots by ca 60{\%}, but had no effect on shoot dry matter production. In control plants at most 70{\%} of the N incorporated in the NO3‐fed roots could have been imported from the shoots, whilst kinetin application reduced this value to ca 40{\%}. Thus root growth was not fully dependent on a supply of N via the phloem. It is concluded that cytokinins affect the pattern of N‐translocation in wheat plants by increasing incorporation of N in dry matter of the shoot, thus leaving less for export. Cytokinins did not play a major role in the regulation of shoot growth and the shoot to root ratio of the present plants.",
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Kinetin application to roots and its effect on uptake, translocation and distribution of nitrogen in wheat (Triticum aestivum) grown with a split root system. / Simpson, Richard J.; Lambers, Hans; Dalling, Michael J.

In: Physiologia Plantarum, Vol. 56, No. 4, 01.01.1982, p. 430-435.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Kinetin application to roots and its effect on uptake, translocation and distribution of nitrogen in wheat (Triticum aestivum) grown with a split root system

AU - Simpson, Richard J.

AU - Lambers, Hans

AU - Dalling, Michael J.

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AB - The root systems of wheat seedlings (Triticum aestivum L. cv. SUN 9E) were pruned to two seminal roots. One of the roots was supplied with a suboptimal level of NO3, the other was deprived of N. Different levels of kinetin were supplied to the NO3‐deprived roots. Root respiration and the increment of C and N in the roots were measured to determine the C/N ratio of the phloem sap feeding the NO3‐deprived roots. Thus, it was possible to determine retranslocation of N from the shoots to the roots, as affected by the rate of kinetin application. It was calculated that the C/N ratio of phloem sap feeding roots growing without kinetin was ca 61. Kinetin application increased this ratio to ca 75, partly due to decreased translocation of N from the shoots back to the roots. Kinetin application decreased the proportion of N that was retranslocated to the roots after translocation to the shoots. Kinetin increased the rate of NO3 uptake per root and the rate of N incorporation in both roots and shoots by ca 60%, but had no effect on shoot dry matter production. In control plants at most 70% of the N incorporated in the NO3‐fed roots could have been imported from the shoots, whilst kinetin application reduced this value to ca 40%. Thus root growth was not fully dependent on a supply of N via the phloem. It is concluded that cytokinins affect the pattern of N‐translocation in wheat plants by increasing incorporation of N in dry matter of the shoot, thus leaving less for export. Cytokinins did not play a major role in the regulation of shoot growth and the shoot to root ratio of the present plants.

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