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Accueil du site → Doctorat → Egypte → Plant - Water - Soil Relationships of Balanites aegyptiaca (L.) Del. in Desert Environments

Ain Shams University (2001)

Plant - Water - Soil Relationships of Balanites aegyptiaca (L.) Del. in Desert Environments

Radwan, Usama Ahmed Abd-El-Wahab

Titre : Plant - Water - Soil Relationships of Balanites aegyptiaca (L.) Del. in Desert Environments

Auteur : Radwan, Usama Ahmed Abd-El-Wahab.

Etablissement de soutenance : Ain Shams University

Grade : Doctor of Philosophy (PhD) in Botany (2001)

The present investigation documents the physiological and morphological responses on the interacting responses of an indigenous desert tree ( Balanites aegyptiaca) ,(D laboratory conditions that are similar to an arid environment. A series of field experiments was conducted to explore the ability of Balanites to tolerate inundation, in the downstream part of Wadi Allaqi, South Eastern Desert, Egypt. Effects of inundation on transpiration, stomata ! conductance and water potential of Balanites revealed that Balanites has a certain tendency to overcome the effect of partial inundation. It also can, tolerate the effect of high temperatures and high photosynthetic photon flux density (PPFD) throughout the whole year. The transpiration rate and water potential showed significant differences in different seasons and they indicated different behaviour due to prevailing conditions. A series of experiments was established under controlled conditions to study the effects of drought using different watering regimes (6%, 9% and 12%), and salinity stress using watering solutions of CaCl2 and NaCl at the ratio 2 : 1 with different electrical conductivity (0, 12, 24, 36, 60 and 72 dS m·1) on two Balanites’ populations (Wadi Allaqi and Kharga) of seedlings. Special attention was paid to examining the response of both, root and shoot systems, to environmental stresses. The study of _ light response curve (photosynthesis) using an infrared gas analyser was carried out. The root system development rate indicated significant differences due to population but not due to watering regimes or salinity treatment. Stem diameter and total leaf area indicated significant differences due to population and to both salinity and watering regimes treatment. Photosynthesis rate, transpiration rate and plant watet’ potential exhibited significant differences due to both treatments and they showed different behaviour attributed to population. The drought stress studies revealed that the Wadi Allaqi collection of Balanites is more efficient than the Kharga collection in using the available water as one of the drought tolerance mechanisms, and more tolerant to salinity, as indicated by photosynthesis and transpiration measurements.

Présentation étendue (EULC)

Page publiée le 15 mars 2019