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.
PY - 1982/1/1
Y1 - 1982/1/1
N2 - 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.
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.
KW - Cytokinins
UR - http://www.scopus.com/inward/record.url?scp=84987028344&partnerID=8YFLogxK
U2 - 10.1111/j.1399-3054.1982.tb04536.x
DO - 10.1111/j.1399-3054.1982.tb04536.x
M3 - Article
AN - SCOPUS:84987028344
SN - 0031-9317
VL - 56
SP - 430
EP - 435
JO - Physiologia Plantarum
JF - Physiologia Plantarum
IS - 4
ER -