Seedling response of three agroforestry tree species to phosphorous fertilizer application in Bangladesh： growth and nodulation capabilities

Triple Super Phosphate, TSP fertilizer, was applied @ 80 kg·ha^-1 as the source of phosphorous on six months old polybag seed- lings of Albizia chinensis, Albizia saman and Pongamia pinnta in nursery beds in Bangladesh. The effects of P-fertilizer on seedling growth and nodulation were comparcd to that of seedlings grown in unfertilized soil or in control at different harvesting intervals. The study revealed that, seedling growth was enhanced significantly with the application of P-fertilizer. The growth was found more pronounced in cases of A. saman and P. pinnata, whereas it was not noticeable and showed depressed growth in case of A. chinensis. The study also suggests that nodulation in terms of nodule number and size was also increased significantly with P-fertilization except in case ofP. pinnata, where higher harvesting intervals lowered the nodulation performance of that species

Inhibitory effects of Albizia lebbeck leaf extracts on germination and growth behavior of some popular agricultural crops

An experiment was conducted to observe the inhibitory effects of the leaf extracts derived from Albizia lebbeck （L.） Benth. On germination and growth behavior of some popular agricultural crops （receptor） of Bangladesh. Experiments were set on sterilized petridishes with a photoperiod of 24 h at room temperature of 27-30℃. The effects of the different concentrations of aqueous extracts were compared to distil water （control.）. The aqueous extracts of leaf caused significant inhibitory effect on germination, root and shoot elongation and development of lateral roots of receptor plants. Bioassays indicated that the inhibitory effect was proportional to the concentrations of the extracts and higher concentration （50%-100%） had the stronger inhibitory effect whereas the lower concentration （10%-25%） showed stimulatory effect in some cases. The study also revealed that, inhibitory effect was much pronounced in root and lateral root development rather than germination and shoot growth.

Effects of stand characteristics on tree species richness in and around a conservation area of northeast Bangladesh

We investigated the effect of tree cover,forest patch and disturbances on tree species richness in a highly diverse conservation area of northeast Bangladesh.A systematic sampling protocol was adopted and 80 sub-plots from twenty five 1 ha plots were used for the vegetation survey.Linear regression analysis was performed to understand the effect of patch area,disturbances and tree cover on tree species richness.Ordination using Redundancy analysis(RDA) and Non-metric Multi Dimensional Scaling(NMDS) were also performed to explore the tree species compositional similarities along the stand characteristics gradient and locations of the sample plots.Our study revealed that,forest patch size has greater influence on species richness.Areas with medium level of disturbances have shown greater species richness.In constrained ordination the selected explanatory variables regulated the richness of common species.Our findings can be useful for better forest management and restoration of landscapes of conservation needs using ecologically important species.

Allelopathic effects of Lantana camara on germination and growth behavior of some agricultural crops in Bangladesh

An experiment was conducted to understand the growth inhibitory effects of aqueous extracts derived from Lantana camara L. （a globally recognized invasive alien weed） on six popular agricultural crops of Bangladesh. The test was conducted in sterilized petridishes with a photoperiod of 24 hours and an average temperature of 29℃. The effect of different concentrations ofL. camara leaf extracts were recorded and compared with control （i.e., distil water）. Result showed different concentrations of aqueous leaf extracts caused significant inhibitory effect on germination, root and shoot elongation and development of lateral roots of receptor crops. Bioassays also indicated that the inhibitory effect was proportional to the concentrations of the extracts and higher concentration had the stronger inhibitory effect whereas the lower concentration showed stimulatory effect in some cases. The inhibitory effect was much pronounced in root and lateral root development rather than shoot and germination.

Effects of inorganic fertilizers on biological nitrogen fixation and seedling growth of some agroforestry trees in Bangladesh

The effects of different inorganic fertilizers （Urea and Triple Super Phosphate （TSP）） on seedling growth and nodulation capabilities of four agroforestry tree species （Albizia chinensis, A. saman, Acacia nilotica and Sesbania sesban） were compared. The nodulation of these seedlings were treated with different fertilizer treatments （at the rate of urea 40 kg·hm^-2, urea 80 kg·hm^-2 TSP 40 kg·hm^-2, TSP 80 kg·hm^-2, （urea＋TSP） 40 kghm 2 and （urea＋TSP） 80 kg·hm^-2） after one month of seed germination. The results revealed that the seedling growth was enhanced significantly with moderate fertilizer treatment. In some cases, the higher levels of fertilizers reduced the seedling growth. The study also revealed that the nodulation in nodule number and size was significantly inhibited by the application of N fertilizer （Urea）, while it was increased significantly with the application of P fertilizer （TSP）. This study improved our understanding and provided insights that would be useful to the farmers in their efforts to amend the soil with inorganic fertilizers in order to enhance plant growth and biological nitrogen fixation.

Tree species diversity in relation to environmental variables and disturbance gradients in a northeastern forest in Bangladesh

Biodiversity has become an issue of global attention because of growing awareness of its importance and its rapid depletion worldwide.Diversity of tree species in relation to environmental and disturbance gradients was examined in three managed forests.Trees were randomly sampled in a survey of 75 circular plots(radius=13 m)with 5 subplots(radius=1 m).Generalized linear model analysis was used with a Poisson distribution log link function to understand the effects of variables(organic matter,organic carbon,nitrogen,potassium,pH,elevation and disturbance)on tree species richness.Canonical correspondence analysis was used to explore ecological relationships among plots.Our result found that the stand characteristics was an important influencing factor in the three forests.Our result showed that the variables had a highly positive influence on tree species richness in the three forests.In ordination,the selected variables governed the richness of tree species.Our study can help identify the most important factors that drive tree species richness in the three managed forests in Bangladesh and in similar ecosystems and inform forest management decisions for conservation according to ecological importance.

Effects of phosphorous fertilizer on seedlings growth and nodulation capabilities of some popular agroforestry tree species of Bangladesh

An experiment was conducted to assess the effect of Phosphorous （P） fertilizer （i.e. TSP or triple super phosphate @ 80 kg/hm^2） on seedling growth and nodulation capabilities of three potentially important agroforestry tree species （Acacia auriculiformis, Albizia lebbeck and Albizia procera） of Bangladesh. The study was conducted in nursery beds with six-month-old polybag seedlings ofA. auriculiformis, A. lebbeck and A. procera. The effects of P fertilizer on seedling growth and nodulation were compared with that of the seedlings grown in control （i.e. unfertilized soil）. The observations revealed that the seedling growth was enhanced significantly with the application of P fertilizer. The growth was found more pronounced in A. auriculiformis, whereas it was not apparent and shows depressed growth in case ofA. lebbeck. The study also suggests that the nodulation in terms of nodule number and size was also increased significantly with the application of P fertilizer.

Bamboo based small-scale cottage industries in the rural areas of Chittagong region,Bangladesh

对孟加拉吉大港地区家庭竹子手工业非农就业的潜力以及对其产生的社会经济效益进行了调查。本地区有40个竹企业,涉及到Hathazcori upazila的4个村庄。80％手工业者的年龄在30～50岁。他们的大多数是未受教育和土地贫瘠的家庭成员。50％的企业是由夫妻或3～5个工人组成的。竹产品主要是满足当地市场的需求。产品是根据季节的变化而决定的。5个产品中,竹书架提供了企业月净收入的41％,平均月净利润约2373.48塔卡,这为促进乡村经济发展起到重要的作用。作者对竹产业发展的状况进行了验证,并提出了建议。