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The Sundarbans mangrove is a highly dynamic ecosystem. Gewa
(Excoecaria agallocha Linn.) is a codominent species, the
merchantable growing stock of which was depleted by 45% during 1959
to 1983. The purpose of this study was to obtain information on
phenology, genetic diversity, improvement of selection, and
suitable propagation system and hedge development and management as
a step towards sustainable management of the species and enhances
the productivity of the mangrove forests. Gewa is a commercially
important hardwood species. So it is an urgent need to improve this
species for maintaining and protecting its genetic erosion. The
present situation calls for improvement and management of this
species for sustainability of the forest. The seed viability
decreases very rapidly within a short time. Natural regeneration of
gewa is limited due to several biological factors. Shortage of
superior seeds/propagules for plantation forestry may be overcome
by using clonal propagation technique. The results suggest that, to
increase the timber yields, productivity and sustainability of the
forest, enrichment plantation by genetically superior stocks is
possible in the mangrove forest.
The present study was conducted to standardize a suitable protocol
of in vitro plant regeneration potentiality of seven strawberry
varieties viz. AOG, JP-2, JP-3, Camarosa, Sweet Charly, Giant
Mountain and Festival. Young leaves, mature leaves and nodes of
seven strawberry varieties were used for callus induction and plant
regeneration. Among the seven strawberry varieties AOG was found to
be the most responsive genotype for primary culture establishment,
callus induction, shoot regeneration and rooting. A total of 40- 45
somaclones from each of the tested varieties were established and
maintained in the field and were considered as Ro plants. There
were no plants found resistance to fungal diseases but somaclones
showed better tolerence than the donor plants. Majority of plants
were found heat sensitive in donor plants but somaclones of AOG SC
3 showed better performance than other somaclones and donor parents
in terms of summer overcoming capacity. These somaclones can be
acceptable commercially if the good characters exhibited are
transmitted through generations or could be used in future breeding
programme for the improvement of strawberry varieties in
Bangladesh.
Meristems isolated from shoot tips of field grown mature garlic
bulbs of five cultivars were cultured in liquid MS medium with 2ip
and NAA for shoot proliferation. In vitro bulblets were produced
from meristem derived shoot clumps in MS with high levels of
sucrose. Rooted plantlets with bulblets were gradually acclimatized
and successfully established in the field. Visual evaluation of the
morphological traits of the meristem derived plants showed that all
plants were normal and free from virus diseases. Substantial yield
increase was observed from meristem derived plants over their
source plants. Shoot tip, leaf base, leaf primordia and bulbil from
field grown mature garlic bulbs of five cultivars were cultured in
MS medium with 2,4-D for callus induction. The calli were
transferred to MS medium without any growth regulators for somatic
embryogenesis. Plantlet regeneration from somatic embryos was
obtained in KIN supplemented MS media. After proper acclimatization
rooted callus derived plantlets with bulblets were transplanted in
the field and somaclonal variation were found in plant height,
number of leaves/plant, bulb diameter/plant, and bulb weight/plant.
Taxonomic investigation of the Cucurbits (family-Cucurbitaceae)
growing throughout the Northern parts of Bangladesh was carried
out. Documentation of species distribution, ecology and indigenous
uses by local people has been made. Lists of the taxa examined with
all synonyms are provided. Taxonomic position, occurrence,
cultivation method, food value (mainly cultivated), uses and
classification are presented and discussed. All the Cucurbits
species studied were collected from the northern parts of
Bangladesh. A total of 24 species under 13 genera of the family
Cucurbitaceae were collected from the study area. Most of the
cultivated species are grown in all districts of Bangladesh. Some
of the species which are sometimes cultivated and sometimes wild
are grown in particular area. Most of the species are distributed
all over the study area, i. e. Benincasa hispida, Citrullus
lanatus, Coccinia grandis, Cucumis melo, Cucumis sativus, Cucurbita
maxima, C. pepo, C. moschata, Lagenaria siceraria, Luffa
acutangula, L. cylindrica, Momordica carantia, M. cochinchinensis,
Melothria maderaspatana, Trichosanthes anguina, T. cucumerina, T.
bracteata and T. dioica.
In vitro propagation of virus free clones through meristem and
subsequent field evaluation of microclones were explored. The
present study also includes callus induction from leaf explant
followed by somatic embryogenesis, plant regeneration from somatic
embryos and subsequent field evaluation of embryo derived plants
for exploring possible occurrence of somaclonal variations. The
meristem culture, somatic embryos and bulblets derived plantlets
after proper acclimatization were transplanted to field and were
grown to maturity along with conventionally grown clove derived
plants as control. The plants were assessed for the occurrence of
somaclonal variation using different morphological and yield
related characters. The results illustrated in the present study
elucidated that meristem culture used for the micropropagation of
garlic could be effective in minimizing the incidence of somaclonal
variation and could be used for the production of virus free
planting materials. In addition, the high incidence of somaclonal
variations generated through somatic embryogenesis may be useful as
an alternative breeding tool for widening genetic basis for the
improvement of new garlic cultivars.
Iron deficiency is the most wide spread nutritional problem in the
world. For increasing the iron contents in four potato cultivars,
in vitro leaf derived calli were transformed with Agrobacterium
tumefaciens strain LBA4404 bearing Ti based binary pCAMBIA2301
plasmid containing selectable marker neomycin phosphotransferase
(nptII) and ferritin gene. Maximum kanamycin resistant and ferriitn
positive calli with the highest transformation frequency were
obtained from Japanese Red by using 50 mg/l kanamycin, 50 mg/l
cefotaxime, the bacterial suspension (OD=1.00 at 600 nm), 70
seconds incubation period, 24 h co-cultivation period in the
presence of acetosyringone (25 mg/l). Putative transgenic plants
were regenerated from the infected calli in medium containing MS +
3.0 mg/l BA + 0.1 mg/l NAA + 50 mg/l kanamycin + 50 mg/l
cefotaxime. Kanamycin resistant plants were analysed with PCR and
RT-PCR for the detection of ferritin gene and its transcript which
reveal that ferritin genes were integrated into the plant genome.
The physiological parameters like PBH, SBH, PH, PAPP and TDM were
increased with the advancement of plant age while LWR, CGR and RGR
decreased with the increase of plant age. The plants under
irrigated conditions produced significantly better performances in
all the characters tested than those of the rainfed plants except
LWR, CGR and RGR. Most of the yield contributing characters were
influenced by irrigation applied at two stages of growth. Primary
branch height and relative growth rate were the highest as
influenced by irrigation applied at one stage of growth. Some
growth attributes like leaf weight ratio and crop growth rate were
the highest under rainfed conditions. Correlation and path
coefficient analysis revealed that plant area per plant showed the
highest positive direct contribution on grain yield and it was
followed by pod number per plant and seed number per plant.
Stability parameters indicated that Barimasur 6 showed the highest
grand mean, regression value nearly one (bi= 1.00) and stability
nearly zero at most of the characters. Out of the six genotypes of
lentil, Barimasur 6 gave very good grain yield under irrigated and
rainfed conditions.
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