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Journal of Environmental Biology

pISSN: 0254-8704 ; eISSN: 2394-0379 ; CODEN: JEBIDP

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        Abstract - Issue Mar 2014, 35 (2)                                                                                                             Back



nstantaneous and historical temperature effects on a-pinene

Cambial periodicity and wood production in Acacia ehrenbergiana Hayne growing on dry sites of Saudi Arabia

 

Ibrahim M. Aref1, Pervaiz R. Khan1, Hamad Al-Mefarrej1, Thobayet Al-Shahrani1, A. Ismail1 and Muhammad Iqbal2*

1Plant Production Department, College of Food and Agriculture Sciences, King Saud University, P O Box 2460, Riyadh 11451, Saudi Arabia

2Department of Botany, Faculty of Science, Jamia Hamdard (Hamdard University), Tughlaqabad, New Delhi, 110 062, India

*Corresponding Author E-mail: iqbalg5@yahoo.co.in 

 

 

 Publication Data

Paper received:

25 February 2013

 

Revised received:

19 March 2013

 

Re-Revised received:

10 July 2013

 

Accepted:

19 August 2013

 

Abstract

This study aimed at elucidating the process of cambial activity and wood formation in Acacia ehrenbergiana Hayne growing in the Al-Baha region of Saudi Arabia, has revealed that the vascular cambium was active for almost the whole year, producing phloem in two flushes (February-March and August-October), and xylem for about 11 months, with varying pace of cell division and differentiation. A close relationship existed between emergence of new leaves and initiation/acceleration of cambial activity and tissue differentiation. Monthly average of the maximum and mean daily temperature showed negative correlation with cambial-zone width. Relative humidity showed positive relationship with xylem differentiation. Leaf water deficit had an adverse effect on the cambial activity (r = -0.94, p < 0.01), xylem production (r = -0.93, p < 0.01) and phloem production (r = -0.97, p < 0.01). On the whole, moderate temperature, low water deficit and high relative humidity and rainfall favored cambial activity and vascular tissue formation. Annual production of xylem was about five times that of phloem. A. ehrenbergiana appears to be a drought-tolerant species by having narrow, dense and thick-walled vessels, thick-walled fibers, high wood density (0.9273 g cm-3), low vulnerability factor (4.20) and the capacity of thriving well at 35 to 47% water-saturation deficit.

 

 Key words

 

Cambial activity, Drought tolerance, Phenology, Water deficit, Xylem production 

 

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