JAAST Table of Content: October 2(4)

Research Articles


Peyman Pourmohammadi.     pp. 45 - 51




Forest products are the connection between the forest as a supply of raw materials and the various markets that are the sources of revenue to the forest owner. There is strong evidence that forest products play a significant role in the livelihoods of the poor living in the rural areas of the world. Forest products are the main source of income for the forest dwelling population in many countries. In countries with industrial forests, the first resource for providing domestic timber is their productive forests. Iran is a country that holds a few timber forests in the north. The northern forests of Iran play an important role in the production and supply industry and they are the only permanent source of production of wood in Iran. Exploitation of these forests can be divided into four types according to forestry projects belonging to: administrations, co-operative companies, government and private companies. Exploitation of the northern forests is being done in four areas of Gilan, Nowshahr, Sari and Golestan. Forest products include: logs, lumber, sleeper, beam and mine woods, Katin, firewood and charcoal. In this study, the production of Iran’s forest products was considered during a 10 year period (from 1997 to 2006). The results showed that the production of forest products had a downward trend and decreased from 1571796 cubic meters in 1997 to 836281 cubic meters in 2006, therefore this has reduced by 47 percent. The maximum volume of production was of firewood in 2006 with 682104 cubic meters and the minimum production was beam and mine woods in 1997 with 4998 cubic meters.

Keywords:  Forest products, logs, lumber, sleeper, beam and mine woods, Katin, firewood , charcoal.

Kehinde Adedeji Adekola.     pp. 52 - 58




This paper studied the effects of food extruder die dimensions on the extrudate expansion indices using twin-screw extruder. The extruder has 59.6 mm screw diameter and screw L/D ratio of 20. The die dimensions considered are die length, die diameter and die temperature. The feed material used is yellow corn flour. Dies with diameter ranging from 2.5 – 5.0 were used to determine the effect of die nozzle diameter on extrudate expansion. Results obtained showed that radial expansion of the extrudate decreased with increasing die diameter. The regression model shows that SME decreased with increasing die diameter. Dies with length ranging from 16 – 54mm with a constant nozzle diameter of 3mm were used to determine the effects of die nozzle length on extrudate expansion. The die length significantly influenced axial expansion of extrudate. Axial expansion increased with increase in die length. A linear regression model was developed to relate die length to extruder SME. The quadratic effect is negligible in this case and as such was not included in the regression equation. Effects of die nozzle L/D on radial expansion of extrudate during extrusion were also studied. Experimental results on the effects of die diameter and die length on flow characteristics revealed that when all other extruder conditions are kept constant, increasing the diameter of the die nozzle causes increase in the volumetric flow rate of extrudate. Flow rate decrease proportionally with increasing die length.

Keywords:  Dies; dimensions; extrudate; expansion; extruder.

Okorocha E.O.A1, Ogbuji R.O2, Onyenobi F. Ijeoma3, Emehute J.K.U1 and Orikara C. C1   pp. 59 - 62




This greenhouse study was carried out in 1999 and 2000 cropping season to identify the ginger varieties in the ginger bank at Umudike that were resistant to root – knot nematodes Meloidogyne spp. The soil around the roots of four –week old ginger seedlings were inoculated with approximately 1,000 Meloidogyne eggs each. After four weeks of development of the nematodes in the ginger test plants, the ginger root systems were harvested and evaluated for nematode damage, rated for gall index and the numbers of females were counted. The densities of the Meloidogyne eggs in the roots at the end of the experiments, were carried out by differential staining followed by counting with aid of a stereomicroscope. Differences in gall index, number of females and total number of eggs in the root systems were observed among the varieties at the end of the experiment. The screening study was repeated for confirmations in year 2000. Results showed that of the seven available varieties in the ginger bank, three (Maran, U.G I and Rio de Jenairo) were resistant while three (U.G II, Himachall Pradesh and St. Vincent) were susceptible and one (Wynad Local) was tolerant in first year. In the second year 2000, U.G II was tolerant while Maran was susceptible. It is remarkable that as low as 1,000 eggs per plant can cause much damage to the roots and that both U.G I and Rio de Jenairo were clearly resistant and could be recommended as intercropping components to farmers.

Keywords:  Ginger, Meloidogyne spp., Resistance screening, Umudike.