Regulation of abscisic acid concentration in leaves of field-grown pearl millet (Pennisetum americanum (L.) Leeke): the role of abscisic acid export

Henson, I E and Mahalakshmi, V and Alagarswamy, G and Bidinger, F R (1986) Regulation of abscisic acid concentration in leaves of field-grown pearl millet (Pennisetum americanum (L.) Leeke): the role of abscisic acid export. New Phytologist, 102 (2). pp. 249-259. ISSN 0028-646X

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Diurnal changes in the ABA concn. in leaves of droughted, field-grown plants of P. americanum were not always correlated with changes in bulk leaf water potential. A rapid decline in ABA content of the leaves following its rise to a peak level in mid-morning, was observed in several time-course studies despite continued water stress. The possibility that the reduction in ABA in leaves was due to an elevated rate of its export was examined by measuring ABA concn. in developing panicles (possible sinks for leaf-produced ABA) and in leaves, and by comparing the amounts of ABA in ungirdled leaves and in leaves heat-girdled at the base of the lamina to block export. ABA concn. in panicles generally paralleled those in leaves, though the peak concn. of ABA in the morning in panicles occurred later than in the leaves in some samplings. Although girdling initially increased ABA concn., it did not prevent a subsequent fall which generally paralleled the decline observed in untreated leaves. The decrease in ABA that occurred despite the block to export and despite continuing stress was attributed to changes in the synthesis or metabolism of ABA within the leaf. The probable rate of export of ABA from leaves, calculated from the changes in its concn. due to girdling, was highest at the time of most rapid ABA accumulation and declined thereafter. The percentage export of recently assimilated C declined similarly. However, the probable absolute rate of export of photosynthate, computed from stomatal conductance and [14C]-export measurements, was not uniquely related to that of ABA

Item Type: Article
Uncontrolled Keywords: Abscisic acid, leaf water potential, diurnal cbanges, export, Pennisetum americanum
Subjects: Mandate crops > Millets
Depositing User: Ms K Syamalamba
Date Deposited: 06 Dec 2011 05:52
Last Modified: 06 Dec 2011 05:52
Official URL:
Funders: UK Overseas Development Administration
Acknowledgement: We are most grateful to Messrs P. V. D. M. Rao, M. Anjaiah, and M. H. Jeffrey for their valuable help with the experimental work, to Dr S. A. Quarrie for the use of the heat-girdling device and to Dr M. Sheron, Dr R. B. Austin and Mr C. L. Morgan for advice on radioactivity measurements. I.E.H. thanks the UK Overseas Development Administration for financial support
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