The experiment was conducted at the Field Laboratory, Department of Agroforestry, Bangladesh Agricultural University, Mymensingh during July - December, 2004. The soil texture is silty loam (FAO 1988). The experiment was carried out by two Factorial Randomized Complete Block Design with three replications. Two factors i.e. trees and orientations of the plots from the tree base. Total number of plots in the experiment was 45. Each unit plots was 2m X 2m. Albida, Akashmoni and Jhau trees (three from each) were involved in this experiment. Thirty - six plots were laid under the trees and nine plots were laid in control (open field). The crown diameter of each selected tree was measured along north - south and east - west axis using stick and measuring tape. The crown area of each tree was calculated from crown diameter using the following formula.
CC= π/4{(D1+D2)/2}2
Where, CC = Crown area (cover) of the tree in m2
D1 = Crown diameter along north - south axis
D2 = Crown diameter along east - west axis
The treatment combinations used in this investigation were as follows:
Factor A: Tree
T1 = Albida (Casuarina equisetifolia)
T2 = Akashmoni (Acacia auriculiformis)
T3 = Jhau (Casuarina equisetifolia)
Factor B: Orientation
O0 = Open field (control)
O1 = North (1m from the tree base)
O2 = South (1m from the tree base)
O3 = East (1m from the tree base)
O4 = West (1m from the tree base)
On 15th July 2004 , the land ploughed and cross-ploughed several times by power tiller until the soil was brought to a good tilth. The fertilizers were applied in the field according to the recommended doses (BRRI, 1998 ); Urea @180 kg/ha, TSP @125 kg/ha, MP @70 kg/ha, Gypsum @60 kg/ha and Zinc sulphate @ 10 kg/ha. One third of urea and all other fertilizers were incorporated with soil during finally land preparation. Urea was applied in two equal splits. One third after 23 days after transplanting and rest one third before flowering at 48 days transplanting. Thirty-five (35) days old seedlings of BR11 rice were collected from the agricultural farm of BAU. Seedlings were uprooted with care from the slightly irrigated seedbed. Two/three seedlings per hill were transplanting with 15 cm x 25 cm spacing at 4 th August 2004. Necessary gap filling was done wi thin 10 days of transplanting. Uprooting and removing from the field controlled weeds. Diazinon 60EC was applied once with urea fertilizer during second installment of top dressing to control insect pests of rice. Top dressing of urea fertilizers was done 1/3rd at 30 days after transplanting and 1/3rd before flowering. Cop was grown under rain fed condition. Prior to each top dressing, plots were weeded manually. Five hills were randomly selected from each plot at maturity to record the data on yield contributing characters like plant height (cm), numbers of total tiller hill-1 , number of effective tillers hill-1, panicle length (cm), number of filled grains/panicle, number of unfilled spikelets panicle-1, 1000 - grain weight (g). The selected hills were collected before crop harvest and necessary information’s were recorded accordingly. The crop was harvested at its full maturity. The data collected at final harvest were coded and analyzed following the appropriate design of the experiment. Duncan’s new multiple range tests were computed in order to show the significant differences between the treatment means (Zaman et al. 1982 ).