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EXOGENOUS POTASSIUM
DIFFERENTIALLY MITIGATES SALT STRESS IN TOLERANT AND SENSITIVE MAIZE
HYBRIDS
G.H. ABBASI1*, JAVAID AKHTAR2, M. ANWAR-UL-HAQ2, SHAFAQAT ALI3,
ZHONG-HUA CHEN4 AND WAQAS MALIK5
Abstract: A hydroponic experiment
was conducted to investigate the role of potassium (K) in extenuating
the injurious effect of salt stress on maize hybrids differing in salt
tolerance. Two salt-sensitive viz., 33H25 and 8441 and two salt-tolerant
viz. 26204 and Hysun-33 maize hybrids were grown for four weeks in half
strength Hoagland’s solution. The nutrient solution was salinized by
three salinity (0, 70 and 140 mM L-1 NaCl) levels and supplied with
three levels of potassium (3, 6 and 9 mM L-1). Salt stress significantly
reduced the plant growth as reflected by a decrease in the plant height,
leaf area, shoot length, shoot fresh and dry weight, relative water
content (RWC), membrane stability index (MSI), chlorophyll contents (chl),
transpiration rate (E), photosynthetic rate (A), internal CO2
concentration (Ci), stomatal conductance (gs), K+/Na+ ratio and
increased the activities of anti-oxidative enzymes superoxide dismutase
(SOD), peroxidase (POD) and catalase (CAT) at 70 mM NaCl, but activities
of SOD, POD and CAT declined at 140 mM NaCl for all four maize hybrids.
Salinity induced diminution in all these attributes was significantly
greater in salt sensitive maize hybrids as compared to salt tolerant
maize hybrids. However, application of potassium counteracted the
unsympathetic effects of salinity on the growth of salt tolerant maize
hybrids, particularly at 9 mM L-1 level. Potassium enhanced growth of
salt-stressed maize hybrids 26204 and Hysun-33 was associated with
increased CAT activity, higher photosynthetic capacity, and accumulation
of K+ in the leaves. These results suggested that potassium application
counteracted the unfavorable effects of salinity on growth of maize by
civilizing photosynthetic capacity of maize plants against
salinity-induced oxidative stress and maintaining ion homeostasis,
however, these alleviating effects were cultivar specific.
1Department of Soil Science, University
College of Agriculture & Environmental Sciences, The Islamia University
of Bahawalpur, Pakistan
2Institute of Soil and Environmental Sciences, University of
Agriculture, Faisalabad, Pakistan
3Department of Environmental Sciences, Government College University,
Faisalabad, Pakistan
4School of Science and Health, Hawkesbury Campus, University of Western
Sydney, Richmond, 2753 NSW, Australia
5Department of Plant Breeding and Genetics, University College of
Agriculture, Bahauddin Zakariya University, Multan, Pakistan
*Corresponding author e-mail:
abbasiuaf@yahoo.com
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