The Influence Of Priming Two Cucumber Cultivar Seeds

J. Duhok Univ. Vol.13, No.1, (Agri. And Vet. Sciences) Pp 112-121, 2010
Fig. (1): Croton shrub is one of the ornamental
plants(Codiaeum variegatum).
MATERIALS AND METHODS
Pot croton (Codiaeum variegatum) was
grown in the greenhouse of Horticulture
Department, Agriculture College, University of
Duhok at 15 \ 9\ 2008.
Leaves with petioles were collected, and the
petioles were removed after leaves washed under
tap water for 30 minutes to remove soil and
other superficial contaminations. The leaves
were cut into 1 cm 2 in size under sterilized
condition (Fig 2). The explants were surface
sterilized with 70% ethanol for 3 minutes in a
laminar air flow cabinet followed by immersion
in a 4 % sodium hypochlorite solution (5%
active chlorine) for 10 minutes and rinsed three
times with sterile distilled water, and then
cultured on MS medium (Murashige and Skoog ,
1962). The medium was supplemented with 30
gl -1 sucrose and solidified with 7 gl -1 agar. The
pH of the medium was adjusted to 5.7± 0.1 befor
autoclaving.
First experiment: The following growth
regulators were added to the medium .
BA (Benzyl adenine) at (0, 1, 2) mgl -1 .
NAA (Naphthalene acetic acid) at
(0, 0.2, 0.4) mgl -1 .
2,4-D (2,4-Dichlorophenoxy acetic acid)
at (0, 0.2, 0.4) mgl -1 .
Each treatment was replicated 10 times with
1 explant. The explants were cultured in growth
room at 25°C in the dark to encourage callus
formation or in the light condition for callus
growth.
When the calli were one month old, they
were transferred to a growth chamber and
maintained under a 16 hour photoperiod and 8
hour darkness under artificial light at an intensity
of 1000 lux. Shoot regeneration was encouraged
by 50 mgl -1 casein hydrolysis and 1 mgl -1 BA
added to the medium.
After 6-8 weeks, the following data were
recorded: percentage of callus induction, average
callus fresh weight (mg) and embryo induction
percentage. All data were statistically carried out
using Complete Randomized Design (CRD)
using 10 replications. Significant differences
among mean values were separated using
Duncan Multiple Range Tests at P≤0.05
(Duncan, 1955).
Second experiment: After somatic embryo
formation from the callus. The embryogenic
callus was weekly subcultured on MS medium
for accelerating the induction of embryoids, with
the removal of dead and dark-brown cells from
the callus. After 6 weeks of subculture, greenish-
yellow, globular pro- embryoids were observed
under microscopic examination and these were
selected and subcultured on the same medium
for maturation according to Robinson et.
al.(2009) and Buchheim et. al.(1989). Matured
somatic embryos (heart- and torpedo shaped)
were transferred to somatic embryo regeneration
medium containing MS salts; After the complete
regeneration of embryoids to plantlets the latter
were transferred to the third experiment. After 4-
6 weeks ,the following data were recorded:
No.of somatic embryo induced from callus, No.
of shoot development, No. of leaves per culture
and average of shoots length (cm).
Third experiment: The explants were allowed
to grow and then transferred to MS medium
with different concentrations of cytokinin (0,
2.5, 3.0, 3.5, 4, 4.5 and 5) mgl -1 BA combine
with (0, 2.5, 3.0, 3.5, 4, 4.5 and 5) mgl -1 Kin.
After 4-6 weeks ,the following data were
recorded: No. of shoots per culture, No. of
leaves per culture and average of shoots length
(cm).
Fourth experiment: Shoots were transferred to
(¼ and ½ strength) MS medium with different
concentrations (0, 0.5 and 1) mgl -1 of NAA, IAA
and IBA alone for in vitro rooting. After 4 weeks
,the following data were recorded: percentage of
root per culture, No. of roots per culture and the
average of roots length (cm). For
acclimatization, rooted plants of croton with well
developed roots and leaves were taken out of the
culture jars washed with water to remove the
agar around the roots. The plantlets were
transferred to plastic pots containing soil mixture
and peat moss (1 :1 by volume). The percentage
survived plant were recorded after 4 weeks from
transplanting.
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