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 the 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.

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This paper deals with the iron status of different species of banana leaves ; the effect of application of sulphur in sail on iron mobilization and the effect of injection of iron salt solution on iron absorption by banana leaves.

Soil and leaf samples were collected from the groves of five edible banana species grown in a green house,  Soil  around the selected banana plants was treated with sulphur both in the plots and in pots applving 100, 200 and 300 kg of sulphur per hectare. Two ml of FeSO₄ solution (5000 ppm) was injected on the  pseudosten at the base of the third youngest leaf. After four weeks, soil  and leaf samples were collected for analysis. Sunflower seedlings grown under similar sulphur treated conditions were collected after 20 days.

It was revealed from the results of the analytical data that iron content in banana leaves vary from one species to the other. But most of the species selected for this work contained higher amount of iron in leaves compared to the iron content of sunflower seedlings. The injection of FeSO4 solution in the pseudostems of iron deficient banana plants gave expedited response in iron absorption by leaves compared to the application of sulphur in soil which was done for increasing the mobilization of iron.

Shrinkage and density were studied for Teak (Tectona grandls) of five age groups ranging from 20 to 60 years at three height positions. Linear shrinkages were evaluated from green condition to 15 and O percent moisture contents. Density was determined on the basis of green and ovendry volumes. Shrinkage and density were found to be Independent of the height of the stem. The overall shrinkage and density were affected by the age factor. The variations in the average values of different age groups were, however, not observed to be significantly different in all cases.

CIvit ( Swlntonia florlbunda ) veneer, dry (10—20 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.

For manufacturing highly water resistant Civit plywood which will also resist fungal lyctus and drywood termite attack, the veneers can be treated with borax or boric acid solutions without adversely affecting subsequent gluing.

The lack of knowledge of treatability of timber species with pressure method may result in poor treatment in respect 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 40:60 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.