Diurnal Changes in Endogenous Abscisic Acid in Leaves of Pearl Millet (Pennisetum americanum (L. ) Leeke) under Field Conditions

Alagarswamy, G and Mahalakshmi, V and Bidinger, F R (1982) Diurnal Changes in Endogenous Abscisic Acid in Leaves of Pearl Millet (Pennisetum americanum (L. ) Leeke) under Field Conditions. Journal of Experimental Botany, 33 (3). pp. 416-425. ISSN 0022-0957

PDF - Published Version
Download (581kB) | Preview


Diurnal variation in leaf abscisic acid (ABA) content was investigated in pearl millet (Pennisetum americanum (L. ) Leeke) growing in the field in the semi-arid tropics and subjected to varying degrees of water stress. There was a two- to three-fold change in ABA content during the photoperiod in three groups of ‘severely’ stressed plants of the genotype BJ 104. Maximum ABA occurred mid-morning (1030 h). ABA levels then declined to a minimum at 1500 h. Changes in ABA content of ‘moderately’ stressed and fully irrigated plants were smaller, but still significant. Though, when averaged over the day, levels of ABA of the five groups were positively related to the degree of water stress, relationships between ABA concentration and total water (Ψ) or turgor (Ψp) potentials varied considerably with time of sampling. Within groups, changes in ABA contents during the day were not always accounted for by changes in Ψ or Ψp. Temporal changes in leaf ABA content similar to those found in BJ 104, and largely unrelated to Ψ, were observed in the genotypes Serere 39 and B282 in a subsequent year. Leaf ABA content of droughted plants (BJ 104) did not decline appreciably overnight despite a marked increase in Ψ. However, a large reduction in ABA content with increase in Ψ did occur following heavy rainfall. Diurnal changes in stomatal conductance (g1) of BJ 104 could not be simply accounted for by temporal changes in total leaf ABA content, even when allowance was made for effects of irradiance and other environmental variables on g1. It is suggested that the sensitivity of stomata to ABA, or accessibility of the hormone to the stomatal complex, changes during the day.

Item Type: Article
Subjects: Mandate crops > Millets
Depositing User: Mr Sanat Kumar Behera
Date Deposited: 18 Oct 2011 08:59
Last Modified: 18 Oct 2011 08:59
URI: http://oar.icrisat.org/id/eprint/2771
Official URL: http://dx.doi.org/10.1093/jxb/33.3.416
Funders: UK Overseas Development Administration
Acknowledgement: We thank Miss C.F.L Reakes and Mr. M.H. Jeffery for assistance with ABA analyses and staff of the millet physiology section at ICRISAT for their help in the field work. I.E.H. Is grateful to the U.K. Overseas Development Administration for financial support and for the provisions of funds to visit ICRISAT.
View Statistics

Actions (login required)

View Item View Item