CIvit ( Swlntonia florlbunda ) veneer,
dry (1J—12 percent moisture content)
boric acid and 1.9 percent
for 10, 25 and 40 minutes,
three-ply plywood.
1.5 mm thick, both green and
were soaked in 1 25 percent
borax solutions separately at 90° —100°C
These were conditioned and glued into
with a ureaformaldehyde adhesive fortified with
melamine, for producing boil-resistant glue-bond. Plywood shear test
samples were prepared and tested in both dry and wet (boiled in water
for six hoyrs and tested while wet) states.
Dry shear tests show that green veneers treated with both boric
acid and borax, and dry veneers treated with borax had the higher
bond strength, while the longest treating time (40 minutes) had the
lowest bond strength, all the differences being significant at the 5%
level. The wet test shows significant differences at the 5% level
between the preservatives, borax treatment producing better bond
strength However, all the treatment combinations resulted in adequate
bond strength for the type of plywood produced.

Th© lack of knowledge of treatability of timber species with
pressure method may result in poor treatment in reipect of penetration
and retention of the preservative chemical Inwood. This knowledge
for our indigenous timber species was not ascertained before. The
relative penetrability of nineteen timber species was, therefore,
determined with Lowry empty cell process using 40 r 60 creosote
and light diesel oil mixture.
Specific gravity of species did not seem to have any bearing
on the penetration cf preservative. Grain structure and presence of
tyloses appeared to be correlated with penetrability of the wood.
The species were classified into four treatability groups according
to the degree of heartwood penetrability.

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Paper pulps have been prepared from Gamar (Gmelina arborea, Roxb.)
wood of four age groups by the kraft process. Cooks were made with
active alkali and sulfidity ranging from 14,94 percent to 21.05 percent
and 14,12 percent to 20,12 percent respectively at 170° C, The best
pulp was obtained with 16 years old gamar wood at 14,94 percent
active alkali and 14,57 percent sulfidity under optimum condition.
Pulp-yield varied from 40,86 percent to 49,35 perecnt at various ages.
The physical strength and other properties of Gamar kraft pulp compared
favourably with those of other hardwood pulps prepared in the Forest
Research Institute, Chittagong,

Teak fruits were experimentally graded by weight and
graded according to size This gave a total 35 weight-cum-size
grades of fruits The germinative and the average seedling production
capacity of the fruits of each grade were tested. It was found that
the results were influenced by the way the data were arranged and
produced. The weight-cum-size arrangement showed confused, unexpected
and unnatural trends which were difficult to explain but the
size-cum-weight arrangement showed a linear relationship between size
of the fruit and the number of seeds which was according to expectation
and in conformity with the results reported earlier It has, therefore,
been concluded that size of the fruit is primary and the weight is
only secondary in determining the quality of Teak fruits. Grading of
Teak fruits by combining size and weight can give fruit lots upto
50-75 percent germinability and average number of 1.00-2 50 seedlings
per fruit.

Excepting bamboo and sungrass, various grass species growing
in the forest lands of Chittagong, Chittagong Hill Tracts and Sylhet
districts of Bangladesh, at present, have practically no use. Five
grass species, namely, Panicum, antidetale, Retz., Themeda arundinacea,
Ridley., Saccharum spontaneum Linn., Thysanolaena maxima, O, Ktze, and
Imperata arundinacea, Cyr., which are available in the area in appreciable
quantities, have been pulped by steaming and soda processes for the
manufacture of insulation boards in equivalent mixtures as well as in
the proportion of their availability in the forests. The pulps obtained
by the steaming process were free-draining but rather dark in colour.
Soda pulps were lighter in colour but comparatively slow-draining.
Yield was high in both the processes.
Rigid structural insulation boards were made both by press-drying
in a hot hydraulic press at low pressure and by cold pressing the
mats and then drying in a force-draft oven. The boards had very
good strength but moderate heat insulating properties, They compared
favourably with the imported ones so far as the moisture resistance
properties were concerned.

It has been found that the nature
pineapple can be improved by treating
The most obvious effect
both in terms of time and quantity.
for canneries. Moreover, fruits can be
obtained all the year round by artificial
flower induction and advantage taken of
the higher prices for ”offseason” fruits
Tremendous works have been done in
this line in different countries specially
in Australia, Hawaii and Puerto Rico and
some in Bangladesh and a few important
of them have been reviewed in this paper
Under natural conditions, a percentage
of pineapple plants do not flower at the
normal time and, in addition, flowering
may spread over several weeks. But with
the application of hormone the plants can
be forced to flower within a shorter
period ensuring uniform cropping, This is
very important when the fruit is grown
and time of flowering In the plants with hormones
has been found to be enhanced flowering The response of the plants to
hormone treatment varied according to the substances used and their
concentration* Other effects of hormone treatment have been found to
be increase in size and weight of the fruit.

Bamboo
42 BANO BIGGY-‘N PATRIKA
i Revised version of the paper presented at the Third Annual Bangladesh Science
blight causing severe mortality, particularly of young
culms, in the village groves of Rajshahi district of Bangladesh is
reported. A brief history of the outbreak of the disease is noted,
A review of bamboo diseases is provided. Symptoms and observed
mode of infections are recorded. Four fungi have been isolated from
diseased bamboo samples. The pattern of isolation strongly suggests
that Conlothyrium fuckelil Sacc. is responsible for the blight.

The paper critically discusses the methods so far developed for
determining the best rotations (years from planting to final cutting)
for forest plantations in order to help professional forestry personnel
to determine the appropriate growing periods for Bangladeshi forest stands.
It is observed that most rotation models which are in use place
a lot of emphasis on the needs of wood producers. The needs of
the industries and other users generally receive less attention, Recent
developments abroad have attempted to rectify this situation. It should
be borne in mind, however, that no single method can be considered
to meet all our needs even for public investment purposes. We are
suggesting means to select the models consistent with maximum
economic growth resulting from income and employment effects on
the nation as a whole. The analysis also presents techniques to decide
the time of the final cutting decision at the end of the predicted
rotation in view of specific changes in the economic ‘climate and
other conditions.

Rhizome assemblies and clump form and growth of nine arboretum
grown bamboo species have been studied. Rhizome stalk has been
found to play an important role in determining the form, shape and
growth of clumps. This is due to not only the characteristic length
of the stalk in some species but also its role in orienting the rhizome
in relation to the centre of the clump and the mother culm in general
and the line of gravity in particular. In areas where bamboos are
worked heavily it is the rhizome stalk that is first affected and may
result in congested clumps in species otherwise monopodial or
loosely tufted.
Rhizomes are commonly attacked by pathogenic soil
ganisms, Parts like rhizome stalks, whole
bud of the rhizome may be partly or wholly consumed or otherwise
become inoperative and although these parts contribute to (he •• development
of rhizome assembly they do not contribute towards the growth
of clump. This reduces the rate of growth of clumps considerably.
Irrespective of species, only 8 percent of the buds develop into
normal culms, 77 percent remaining dormant and 15 percent are damaged
by pathogenic soil mlcrooganisms. It has been concluded tha- application
of antipathogens individually or in combination with fertilizer will
ameliorate the conditions of growth and considerably increase the
outturn.