New Zealand Journal of Crop and Horticultural Science
abstracts
Differences in salinity tolerance for growth and water-use efficiency
in some amaranth (Amaranthus spp.) genotypes
E. N. Omami*
P. S. Hammes
P. J. Robbertse
Department of Plant Production and Soil Sciences
University of Pretoria
Pretoria 0002, South Africa
*Present address: Moi University, Horticulture Department, P.O. Box 1125, Eldoret,
Kenya. email: s21217956@tuks.co.za;
elizabethomami@yahoo.com
Abstract Amaranth (Amaranthus spp.) is a promising C4 crop for
semi-arid regions because of its high nutritive value and its ability to adapt
to diverse environments. Data on the tolerance of amaranth to salinity stress
are lacking. The response of four amaranth genotypes (A. tricolor, Accession ’83, A.
hypochondriacus, and A. cruentus) to saline water was analysed
for growth, gas exchange, water use, and leaf anatomical changes. The study
was conducted in a greenhouse. The treatments consisted of saline water at
0, 25, 50, 100, and 200 mM NaCl, equivalent to electrical conductivities
of 1.2, 4.1, 7.0, 12.8, and 24 dS m–1, respectively. Increasing NaCl in the medium decreased
plant height, leaf number, and leaf area. Photosynthetic rate and stomatal conductance
were significantly reduced by salinity. A. tricolor and Accession ’83
did not survive in the 200 mM NaCl treatment. Shoot growth was reduced
and at 50 and 100 mM NaCl the reduction was greater in A. tricolor and
Accession ’83 than in A. hypochondriacus and A. cruentus.
Water-use efficiency increased with increasing salinity and ranged from 3.9
g in A. tricolor to 6.7g dry mass kg–1 H2O in A. cruentus when
plants were salinised with 100 mM NaCl. Specific leaf area (SLA) decreased
with salinity and differed between genotypes. A negative relationship between
SLA and water-use efficiency was observed over the four amaranth genotypes. A.
tricolor and Accession ’83 had thinner leaves, more stomata per unit
leaf area, and larger stomatal apertures than A. hypochondriacus and A.
cruentus.
Keywords Amaranthus; gas exchange; growth; salinity tolerance;
water-use efficiency
New Zealand Journal of Crop and Horticultural Science, 2006, Vol.
34: 11–22
0014–0671/06/3401–0011 © The Royal
Society of New Zealand 2006
H04079; Online publication date 19 January 2006
Received 15 September 2004; accepted 9 September 2005
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