Three Active Phytotoxic Compounds from the Leaves of Albizia richardiana (Voigt.) King and Prain for the Development of Bioherbicides to Control Weeds

The global population is increasing day by day. To meet the food demand for such a huge number of people, crop production must increase without damaging the environment, and to prevent synthetic chemical herbicides from polluting the environment, controlling weeds using bioherbicides is essential. Accordingly, using phytotoxic substances obtained from plants for biological weed management has attracted attention. The plant Albizia richardiana possesses phytotoxic compounds that have been previously recorded. Hence, we have conducted this research to characterize more phytotoxic compounds in Albizia richardiana. Aqueous methanolic extracts of Albizia richardiana plant significantly restricted the growth of the examined plants lettuce and Italian ryegrass in a species- and concentration-dependent manner. Three active phytotoxic compounds were isolated through various chromatographic methods and identified as compound 1, 2, and 3. Compound 3 exhibited stronger phytotoxic potentials than the other two compounds and significantly suppressed the growth of Lepidium sativum (cress). The concentration of the compounds required for 50% growth reduction (I50 value) of the Lepidium sativum seedlings ranged between 0.0827 to 0.4133 mg/mL. The results suggest that these three phytotoxic compounds might contribute to the allelopathic potential of Albizia richardiana.

Phytotoxic Activity and Growth Inhibitory Substances from Albizia richardiana (Voigt.) King & Prain

Albizia richardiana, a fast-growing, large deciduous tree belonging to the Fabaceae family, grows well in hot and humid areas but mainly grows in the tropics of the Old World. The medicinal and other uses of Albizia richardiana are well documented, but the phytotoxic effects of this tree have not yet been investigated. We conducted this study to investigate the phytotoxic activity of Albizia richardiana leaves and to identify growth inhibitory substances for controlling weeds in a sustainable way. Aqueous methanol extracts of Albizia richardiana leaves greatly suppressed the growth of cress and barnyard grass seedlings in a concentration- and species-dependent manner. Two phytotoxic substances were separated using several purification steps and characterized through spectral analysis as dehydrovomifoliol and loliolide. Dehydrovomifoliol and loliolide significantly arrested the seedling growth of cress in the concentrations of 0.1 and 0.01 mM, respectively. The extract concentrations needed for 50% growth inhibition (I50 values) of cress seedlings were 3.16–3.01 mM for dehydrovomifoliol and 0.03–0.02 mM for loliolide. The results suggest that these two allelopathic substances might play a vital role in the phytotoxicity of Albizia richardiana leaves.

Study on Particleboard made from Nipa palm (Nypa fruticans) stem wood and Rajkoroi (Albizia richardiana) wood

The study was conducted to find out the suitability of making particleboard using nipa palm (Nypa fruticans) stem wood and rajkoroi (Albizia richardiana) wood chips. Particleboards were fabricated at six different ratios of nipa palm stem and rajkoroi wood chips such as 100:0, 75:25, 50:50, 25:75, 10:90 and 0:100. Characteristics of particleboards such as modulus of rupture, internal bond strength, water absorption, thickness swelling and moisture content were measured. Results shows that particleboards made from 100% rajkoroi wood chips have the highest static bending properties and highest tensile strength properties of other particleboards but 100% nipa palm stem wood chips have the lowest static bending and lowest tensile strength properties of other particleboards. 10% nipa palm stem wood chips particleboard have the highest bending strength and tensile strength is better than 100% nipa palm stem wood chips and other mixing chips of particleboards. Mechanical, water resistance and dimensional stability properties were tested according to Indian standard specification. Tensile strength passed the British and German standard specification and nearest to Bureau of Indian Standard, bending strength was found nearest to Indian Standard but lower than German and British Standard specification. Strength property of rajkoroi wood chips particleboard is higher than nipa palm steam wood chips particleboard but dimensional stability is lower than nipa palm steam wood chips particleboard.

Study on Rajkoroi (Albizia richardiana) for Ply and Particleboard Manufacture

The suitability of Rajkoroi (Albizia richardiana) for plywood and particleboard manufacture has been determined. Study shows that 1.5mm thick smooth and figured veneer can be peeled and dried easily. Three-ply plywood were made using veneer of this species bonded with liquid urea formaldehyde glue of 50% solid content extended with wheat flour and catalyzed with 2% hardener (ammonium chloride) under the three specific pressures, such as 1.05 N/mm2,1.40 N/mm2, 1.76 N/mm2 in three replications at 6 minute press time and 120°C press temperature. Dry and wet shear test were conducted on the samples and their shear load at failure per unit area and percentage of wood failure were determined. 1.05 N/mm2 Pressure was found best for the manufacture. The particleboards of Rajkoroi (Albizia richardiana) were tested for determining the strength & dimensional stability. Tensile strength passed the German and British Standard Specification. Bending strength found to be nearest to the Bureau of Indian Standard but lower than German and British standard Specification.

Effect of Chromate-Copper-Boron preservative treatment on physical and mechanical properties of Raj koroi (Albizia richardiana) wood

This experiment was carried out to analyze the effects of CCB (chromate-copper-boron) preservative treatment on physical and mechanical properties of Albizia richardiana wood using dipping method. Retention of preservative was maximum at 8% concentration of the preservatives. Based on the retention at this concentration, the physical and mechanical properties of the treated wood were examined. The density of untreated A. richardiana wood was 521 kg/m3. It changed to 542 kg/m3 on treatment. This increase in density by 2.30% for treated wood was significant. On the other hand, modulus of rupture (MOR) increased significantly from 93 to 107 N/mm2 on treatment of the wood. The modulus of elasticity (MOE) increased from 3205 to 4861 N/mm2. Physical and mechanical properties of the wood improved by treating with CCB preservative.Bangladesh J. Sci. Ind. Res. 50(3), 189-192, 2015

Albizia richardiana King & Prain as a raw material for ply and particleboard

Woods of Albizia richardiana has been studied for assessing the suitability for plywood and particleboard manufacture. It was found that 1.5 mm thick smooth and figured veneer can be peeled and dried easily. Three-ply plywood were made using veneer of this species bonded with liquid urea formaldehyde glue of 50% solid content extended with wheat flour and catalyzed (ammonium chloride) with 2% hardener under the three specific pressures, viz,1.05 N/mm2, 1.40 N/mm2, 1.76 N/mm2 in three replications at 6 minute press time and 120°C press temperature. Dry and wet shear test were conducted on the sample and their shear load at failure per unit area and percentage of wood failure were determined. 1.05 N/mm2 pressure for the manufacture of plywood was found to be the best. The physical and mechanical properties of Albizia richardiana wood particleboard were studied. The particleboards were tested for determining the strength and dimensional stability. The tensile strength 0.56N/mm2 passed the British and German standard specification, bending strength (modulus of rupture10.80N/mm2) was found nearest to Indian Standard but low German and British standard specification.