CONTENTS

SUBBA REDDY et al
from the observations of Ravidas et al. (1992), Devi
et al. (2007) and Kumar et al. (2007) in gladiolus.
GA 3
, NAA and BA at different concentrations
significantly increased the mean spike length, number
of florets and number of spikes per plant. These
treatments were consistent and equally effective in
increasing the leaf area almost during the entire crop
growth period. The increase in leaf area thereby
increased the assimilate synthesis, might have
contributed to increase in spike length by these
treatments. The increased spike length with GA 3
might
be due to rapid inter nodal elongation as a result of
increased cell division and cell elongation in the
intercalary meristem. As GA 3
promotes vegetative
growth and increases the photosynthetic and
metabolic activities causing more transport and
utilization of photosynthetic products this might have
resulted in increased spike length. Mukhopadhyay
and Banker (1986) also reported significant increase
in spike length with GA 3
in the gladiolus cv.
Friendship. Similar results were also reported by
Ravidas et al. (1992), Devi et al. (2007), Rajesh
Bhalla and Ajay Kumar (2007). Flower inducing ability
of BA was reported by several workers under in vitro
as well as in vivo conditions. Induction of flowering
may be due to its ability to alter the assimilate
distribution (Ogawa and King, 1994) i.e. the theory of
nutrient diversion (Sachs et al., 1979).
TIBA recorded minimum spike length.
Reduced spike length with TIBA might be due to its
ability to inhibit polar transport of auxins in cell
elongation and reduced photosynthetic efficiency.
This view gets support from the observations of
Ravidas et al. (1992) and Devi et al. (2007) in
gladiolus. Number of florets per spike was maximum
with GA 3
, NAA and BA treatments. The lowest
number of florets were recorded with TIBA. Increase
in number of florets per spike with GA 3
treatments in
gladiolus have been reported by Rajesh Bhalla and
Ajay Kumar (2007), Dataram et al. (2001) and
PranavRana et al. (2005), who obtained the highest
number of florets per spike by application of GA 3
at
100 ppm. NAA treatments resulted in production of
maximum number of florets per spike which might
be due to short inter nodel length. The lowest number
of florets per spike with TIBA might be due to reduced
plant height and spike length. Devi et al. (2007) also
reported similar results while investigating with NAA
and TIBA in gladiolus.
Results from the present study indicated that
the number of replacement corms per mother corm
was significantly highest in GA 3
followed by BA and
NAA. PranavRana et al. (2005) reported similar
results with GA 3
treatments (100,250 and 500 ppm)
in gladiolus. Singh et al. (2002) also noticed highest
number of corms per plant by with GA 3
followed by
NAA at 200 ppm and BA at 100 ppm treatments in
gladiolus. TIBA recorded the lowest number of
replacement corms per mother corm. Devi et al.
(2007) also reported similar results with GA 3
, NAA
and TIBA in gladiolus. Gladiolus has two sources
for planting viz. corm and cormel which can serve as
reserve food material in the initial stages, and
photosynthesizing leaves in later stages. Likewise it
has two competing sinks,viz., flower spike and the
developing corm and cormels. Plant growth regulators
in all the concentrations recorded maximum number
of replacement corms, cormels and propagation
coefficient. They might have promoted the sink
activity of developing corm and cormels at the
expense of flower spike, which may be the reason
for increase in number of corms and cormels. Similar
results were also observed by Tawar et al. (2007) in
gladiolus. The increase in size and weight of corms
with the application of plant growth regulators could
be attributed to the ability to increase the number of
leaves which in turn increased the photosynthesis
and photosynthetic assimilates. These assimilates
were transported to the daughter corms, thereby,
increasing their size and weight. Supportively, lowest
values for corm weight were recorded with control.
Similar results of increase in size and weight of
gladiolus corms have been reported by Maurya and
Nagda (2002), Umarao et al. (2007 b) and Vijay Kumar
and Singh (2008). The data on number and weight of
cormels per corm revealed that both the parameters
differed significantly due to plant growth regulator
treatments. Among the plant growth regulator
treatments, more number and maximum weight of
cormels per corm were recorded with BA, followed
by TIBA , GA 3
and NAA. Tawar et al.(2007) and
Havale et al. (2008) have reported that BA 50 ppm
recorded the highest values for number of corms and
cormels, weight of corms and cormels. Maximum
number of cormels and weight of cormels was with
12