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As regards the Mg and Ca uptake potential the behaviour
of all genotypes was erratic (Tables
2 to 4). However, Nayab mutants displayed greater Mg and
Ca uptake at 4 and 8 weeks stage but showed erratic trend in
straw at maturity as compared to their parent. This
indicates the rapid translocation of Mg and Ca from shoot to
the aerial parts. Mutant-13 and 39 had consistently lower Mg
and Ca accumulation at 4 and 8 weeks stage than their parent
and Mexi-Pak which indicate that these genotypes are unable
to absorb as much Mg and Ca as available in the growing
media and therefore classified as inefiicient genotypes for
Mg and Ca uptake and have lower Mg and Ca requirement than
their parent. Similar genotypic differences in Mg and Ca
uptake and utilization by wheat were reported by MEYERS
(1960), KLEESE et al (1968) and CLARK (1976).
Na uptake differences among all genetypes were
non-significant (Tables 2 to
4). All the genetypes behaved differently at different
growth stages. However, most of the mutants displayed higher
Na uptake as different developmental stages as compared to
their respective parents. Mexi-Pak was found to be the most
efficient variety in Na uptake at all sampling dates.
Mutant-38 like all other elements retained its superiority
with respect to high amount of Na uptake at different growth
stages than all other C-591 genotypes which indicate that
M-38 has greater Na uptake efficiency than its parent and
M-7 and M-28. All Nayab mutants were higher in Na content
than their parent in straw at maturity, whereas C-591
mutants (M-7 and M-28) were inferior to their mother
cultivar at all growth stages under both sets of conditions.
Gamma irradiated mutants displayed general superiority over
EMS-derived mutants.
The results discussed above clearly indicate that mineral
uptake from soil is not only influenced by the environmental
conditions but to a greater extent by their hereditary
potentialities. Similar conclusions about hereditary
variations in plant nutrition were drawn earlier (HARVEY
1939 ; COLLANDER 1941). Based on some elegant experiments
BEADLE & TATUM (1959) reported that many nutritional
variations among plant varieties are the result of single
gene mutation which exerts an infiuence on the absorption
and utilization of mineral nutrients. It is evident from the
present results that there is wide genetic variation among
the wheat genotypes tested in their absorption, accumulation
and translocation of mineral nutrients from the growing
media. The genetic differences may reflect the differences
in the mechanism of ion transport which is considered to be
under genetic control (EPSTEIN & JEFFERIES 1964 ;
EPSTEIN 1972 ; CACCO et al 1976, LAUCHLI 1976).
Therefore, the genetic variants among the genotypes are the
possible factors affecting the uptake of mineral nutrients
(JENSEN & PETTERSSON 1980) in the present studies.
It is concluded that mineral uptake studies provide
guideline for the characterization and breeding of
nutritionally efiicient genetypes.
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