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Studies on the Architecture and Early Development of Roots of Acacia Auriculiformis and Leucaena Leucocephala

A. D. Lama
Institute of Forestry and Environmental Sciences, University of Chittagong, Chittagong- 4331, Bangladesh

M. Kamal Hossain
Institute of Forestry and Environmental Sciences, University of Chittagong, Chittagong- 4331, Bangladesh

Abstract/ Executive Summary:

Thirty months old saplings of Acacia auriculiformis and Leucaena leucocephala were excavated and root systems were systematically described and horizontal angles, cross-sectional area (CSA) and maximum depths of all roots >1 mm in diameter were recorded. Symmetry of root systems, maximum and minimum numbers and CSA of roots sectors of various sizes were examined. L. leucocephala had more roots growing in 30 cm radius than A. auriculiformis, whereas in the case of branching A. auriculiformis had more branching than L. leucocephala. Root depth was more far from the centre of root system (L. leucocephala had 11, 13 and 16 cm at 15, 30 and 45 cm radii respectively, whereas A. auriculiformis had 13, 15 and 18 cm at 15, 30 and 45 cm radii respectively). Both the species had more rooting depth (L. leucocephala had 36 cm and A. auriculiformis had 16 cm) in south east direction but there were more roots (L. leucocephala had 29 and A. auriculiformis had 11) in south west direction and less (L. leucocephala had 19 cm and A. auriculiformis had 8) in north west direction. Total roots length of L. leucocephala had 43 m and A. auriculiformis 20 m.

Keywords: Architecture, Cross-sectional area, Dominant root, Root symmetry.

Location: Chittagong University Campus

Start Date:

End Date:

Program Area: Crop-Soil-Water Management

Commodity: Tree

Objectives:

To study the morphology, size, depth and symmetry of the root system of these two species.

Methodology:

Saplings of thirty month old Acacia auriculiformis and Leucaena leucocephala were selected for the root study from the plantations of Chittagong University Campus. Three saplings of each species (A. auriculiformis and L. leucocephala) were selected randomly from the site for intense measurement. Roots systems were carefully excavated, weighed and transported to laboratory for detail measurement. The excavation task was performed in September, 2003. The above ground parts of the felled trees were measured by collar diameter (cm), height (m), green weight and oven dry weight. All the six roots systems, three of each species after through cleaning and weighing transported to laboratory for detail measurement. For measuring, each root system were oriented, centered and clipped on root measuring table. For each single root, diameter (≥1 mm), depth and bearing were measured at three radii from the stem centre (15, 30 and 45 cm), The diameters were taken in two directions on every occasion to get the cross-sectional area of the root. Notes of tap roots and breakage were taken. Length of tap root, 1° lateral roots and 2° lateral roots were measured. The number of all roots (≥1 mm in diameter) and their cross -sectional area (CSA) were totaled for each radius separately and for the entire root system. Number and CSA were summed up for sectors of various widths (120⁰, 240⁰ and 360⁰) of the entire root system as well as radius wise. The total length of roots (1⁰, 2⁰ laterals and tap root) were calculated. Dominant roots were calculated in three different ways (a) the 90% rule; where all roots, starting with the biggest, up to 90% of total CSA were defined as dominant roots; (b) the 8% rule; where all roots > 8% of the total CSA were defined as dominant roots.

Source of Information: JOURNAL OF FORESTRY & ENVIRONMENT 3:77 - 84, 2005

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The extensive measurements of the below-ground compartment in this study revealed that there were deformities in root system at the depth of 20 cm due to polythene seedling. L. Leucocephala had an average of 23 roots at 15 cm from the centre of root system and the number of root decreases as the distance increases from the center whereas A. auriculiformis had 14 roots at 15 cm radius and number of roots decreases as the distance increase from the centre of the root system.The number of root branching increases as the distance increases from the center of the root system. A. auriculiformis had more branching in comparison to L. leucocephala. L. leucocephala had a total roots length of 43.43 m and only 2⁰ laterals had 21.51 m length. Whereas, A. auriculiformis had a mean total of 20.01 m and only 2⁰ had 8.68 m long. The numbers of roots were more in 120°-240° section in case of L. leucocephala whereas A. auriculiformis had more root in 0⁰_120⁰. Both number of roots and root area seemed to concentrated along the contour lines than uphill or downhill as reported. L. leucocephala had more dominant roots than Acacia auriculiformis.

Knowledge Management: Journal