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Genotypic variation in mineral uptake
efficiency in wheat mutants under different cultural regimes
A.S. LARIK, H.M.I. HAFIZ* and Y.A.
AL-SAHEAL
Department of Crop Production, Gassim College of
Agriculture, King Saud University (Gassim Branch) Saudi
Arabia
The genetic improvement of bread wheat, Triticum
aestivum L. obtained by breeding is due partly to the
incorporation of traits which are comparatively easily
recognised such as disease resistance and lodging. However,
even when these limiting factors are eliminated from the
environment the different genotypes display varying response
to mineral nutrients, presumably due to their different
genetic makeup and physiological superiority (BlNGHAM 1967).
The mineral uptake capability of a genotype plays an
important role in the performance of that particular
genotype (RASMUSSON et al 1971 ; SAGGAR et al
1974 ; SIMS & PLACE 1968).
The present investigations were undertaken to study the
genetic differences in the induced mutants and their mother
cultivars with respect to the differential uptake,
accumulation, translocation and utilization of N, P, K, Mg,
Ca and Na elements at different ontogenetic stages of wheat.
Earlier investigations have demonstrated clear differences
amongst these mutants, mother cultivar and a commercial
variety for many morphological, agronomical and
physiological characters (LARIK 1978, 1979 ; LARIK &
HAFIZ 1981, 1983 ; LARIK et al 1984a, b ; SIDDIQUI
& ARAIN 1974).
Material and Methods
Homogeneous seeds of three cultivars of bread wheat
Triticum aestivum L. em. Thell (2n=6x=42=AA BB DD)
viz., C-591 (Locally bred), Nayab and Indus-66 (Mexican
origin) and three phenotypically stable mutants of each
variety were grown under field and pot house conditions at
the Botanical Garden, Sind Agriculture University, Tando
Jam, Pakistan. Seeds of different cultivars were drilled in
the beds in five rows 30.5 cm apart and 2 m long at the rate
of 100 kg/hectare. The experiment was laidout with
randomized complete block design with five replications. The
area of main plot was 24x20 m and sub-plot was 2.0 x 1.5
m.
Earthen pots measuring 22x20 cm were filled with 2.5 kg of
air dried soil. Soil was irrigated with 500 ml of tap water
one day before sowing. Twelve seeds per pot of 13 genotypes
were planted at about 2 cm depth with marked glass rod. The
experiment was planned with completely randomized design
having five replications. Thus, altogether 195 pots were
used i.e. 65 pots for each harvest. Mechanical and chemical
analysis of soil is given in Table
1.
Standard dose of NPK fertilizers 54 kg N, 27 kg
P2O5 and 13.5 kg K2O per
acre were used as mineral nutrients for the crop. Ammonium
nitrate, Diammonium phosphate and Potassium hydrogen
phosphate were the source of NPK. Full dose of fertilizer
was broadcasted and ploughed in the field, before sowing. In
pots the amount of mineral nutrients per pot was calculated
equivalent to the field rate on soil weight basis. The full
dose was applied by thoroughly mixing it in the soil of each
pot before irrigating the soil for sowing.
Plant samples for chemical analysis were taken at three
different intervals of four weeks and eight weeks after
sowing and at maturinty. Samples were dried at 70C in an
oven and grinded by the sample grinder. One gram from the
grinded sample were used for chemical analysis. The samples
were digested by H2SO4 (5 ml per gm)
and H2O2 method. The extract was
diluted to 100 ml with distilled water and was used for
determining the nitrogen, phosphorus, potassium, magnesium,
calcium and sodium content in the samples (JACKSON 1958).
Total nitrogen was determined by the modified microkjeldahl
method. P content was determined Colorimetrically using
Bartons Yellow color method on Spectronic-20 at 465 mmicro.
Ca, K, Na were analysed by Flame photometry using Hangarian
Flame Photometer. Mg was determined by the absorption
spectrophotometry method with atomic absorption.
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