Osmotic adjustment to water stress in pearl millet (Pennisetum americanum [L.] Leeke) under field conditions

Henson, I E and Mahalakshmi, V and Bidinger, F R and Alagarswamy, G (1982) Osmotic adjustment to water stress in pearl millet (Pennisetum americanum [L.] Leeke) under field conditions. Plant, Cell & Environment, 5 (2). pp. 147-154. ISSN 1365-3040

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Abstract. Osmotic adjustment, a mechanism whereby plants maintain positive turgor despite low water potential (ψ), was investigated in pearl millet (Pennisetum americanum [L.] Leeke) in three types of field experiment at Hyderabad, India: 1.Osmotic adjustment during the growing season was evaluated by comparing solute potential (ψs) of leaves taken at midday from irrigated and droughted plots and allowed to rehydrate in the laboratory. The degree of seasonal adjustment was also estimated by comparing observed values of ψs in the field with those expected if ψs decreased solely in proportion to water loss. Both types of assessment indicated the maximum seasonal adjustment to be about 0.2 MPa. The cultivars BJ 104 and Serere 39 differed in their capacity to adjust osmotically over the season; Serere 39 was least able to osmoregulate. 2.Measurements of diurnal variations in ψ and ψs in BJ 104 revealed osmotic adjustment during the afternoon hours. At a given value of ψ, turgor (ψp) was about 0.1 MPa higher in irrigated, and over 0.2 MPa higher in droughted plants, in the afternoon, than in the morning. 3.Osmotic adjustment of different leaves within the canopy was investigated. Upper leaves had lower ψ than basal leaves. Differences in ψ were matched by gradients in ψs, so that turgor was similar for all leaf layers.

Item Type: Article
Uncontrolled Keywords: Pennisetum americanum (L.) Leeke, Gramineae, pearl millet, osmotic adjustment, water stress
Subjects: Mandate crops > Millets
Depositing User: Mr Sanat Kumar Behera
Date Deposited: 18 Oct 2011 12:28
Last Modified: 20 Jan 2012 12:54
URI: http://oar.icrisat.org/id/eprint/2858
Official URL: http://dx.doi.org/10.1111/1365-3040.ep11571559
Funders: UK Overseas Development Administration
Acknowledgement: We are most grateful to R.B. Austin, P. Innes, D.W. Lawlor and S.A. Quarrie for their critical comments on the manuscript. We should like to thank G.D. Prasad Rao for his help with data analysis, and member of the staff of the millet physiology section at ICRISAT for their assistace with the field experiments. I.E.H. Is grateful to the UK overseas Development Administration for financial support and for the provision of fund to visit ICRISAT.
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