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Plant
growth and foliar characteristics of faba bean (Vicia faba L.) as
affected by indole-acetic acid under water-sufficient and
water-deficient
conditions
A.
Husen1, M. Iqbal2* and I.M. Aref3
1Department of
Biology, College of Natural and Computational Sciences, University of Gondar,
P.O. Box 196, Gondar, Ethiopia
2Department of
Botany, Faculty of Science, Jamia Hamdard, Hamdard Nagar, New Delhi-110 062,
India
3Department of
Plant Production, College of Food and Agricultural Sciences, King Saud
University, P.O. Box 2460, Riyadh, Saudi Arabia
*Corresponding
Author E-mail: iqbalg5@yahoo.co.in
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Key
words
Drought stress,
IAA application,
Net photosynthetic rate,
PSII efficiency,
Water status
Publication Data
Paper
received: 21.01. 2016
Revised
received: 26. 04.2016
Re-revised
received: 29.07.2016
Accepted: 13.09.2016
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Abstract
Aim: As water is
crucial for survival, growth and yield of plants, it is highly desirable to
devise strategies for enhancing drought tolerance in plants. This study
investigates the impact of foliar application of indole acetic acid (IAA) on
plant growth and leaf characteristics of faba bean (Vicia faba L.)
under normal and water-deficit conditions in order to determine its role in
drought resistance of plants.
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Methodology:
In
a pot experiment, 4-week-old seedlings were sprayed daily with IAA (0, 15, 30
and 45 mg l-1) for 15 days. These seedlings were then maintained under (a)
regular watering with 100% field capacity, and (b) water stress created by
stopping watering for 5 days. Fifty-day-old seedlings were sampled for
analyzing the growth, water content and photosynthetic parameters by standard
methods.
Results:
Water-deficit
condition reduced plant growth, dry mass production, pigment concentration,
maximum quantum yield of PSII (Fv/Fm), stomatal conductance (gs),
net photosynthetic rate (Pn), transpiration rate (E) and
relative water content (RWC). IAA application enabled the plants to withstand
water stress and reduced the expected loss by about 18% in root length, 7% in
shoot length, 10% in basal stem diameter, 11% in number of branches, 3% in
number of leaves, 20% in leaf length, 22% in leaf area, 48% in root dry mass,
34% in stem dry mass and 26% in leaf dry mass. The loss was also mitigated by
44% in chl a, 39% in chl b, 60% in carotenoids, 9% in Fv/Fm,
36% in gs, 63% in Pn, 35% in E and 52% in RWC of the
leaf.
Interpretation:
Water-deficit
hindered the vegetative growth of seedlings by affecting adversely the
dry-mass production, photosynthetic pigments, gaseous exchange, photochemical
efficiency and water status of plants, while IAA application promoted these
parameters not only in normal but also in water-stressed conditions. The 45
mg IAA l-1dose proved to be most effective.
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