Category Archives: Volume 23 No. 1 (2001)

Mechanization of rice production in the Philippines: trends and perspectives


Author: Caesar Joventino M. Tado

Abstract

The present level of rice mechanization in the Philippines is still insufficient to significantly reduce the cost of rice production and for farmers to attain high level of competitiveness relative to those of neighboring rice-producing countries. Sustained support and a consistent mechanization policy of the government are needed. for agricultural modernization through mechanization of farm operations to take off. Aside from increasing the efficiency of production and reducing postharvest losses, farm mechanization can serve as a catalyst for the implementation of integrated rural and agricultural development programs of the government.

Keywords : agriculture, development, mechanization, rice.

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Desorption isotherms of sweetened maturing coconut meat at different temperatures


Author(s): Lemuel M. Diamante

Abstract

The main objective of the study was to obtain the desorption isotherms of sweetened maturing coconut meat at different temperatures (50, 60 and 70°C). A static gravimetric technique was used for the desorption isotherm determination of the material using a standard procedure. Results revealed that the desorption isotherms of sweetened maturing coconut meat were of type III according to the BET classification, The increase in the amount of sorbed water at a given water activity with the decrease in temperature is consistent with the theory of physical adsorption. A modified Caurie equation can describe the effect of temperature. on the desorption isotherms of sweetened maturing coconut.. Using this equation for analysis, the results suggest that when drying of sweetened maturing coconut meat is done at higher temperatures (above 70°C) the equilibrium moisture content (EMC) of the sample is not greatly affected and attains a value of less than 1% dry basis. However, when drying is done at lower temperatures (below 60°C), the relative humidity of the drying air is higher and giving higher EMC of the sample. The net heat of desorption for sweetened maturing coconut meat increases as the moisture content decreases which is expected for most food products. The relationship between the net heat of desorption and moisture content of the product can be expressed by an exponential equation. Using this equation for analysis, the results showed that as the final moisture content of the product decreases the energy requirement increases.

Keywords : desorption isotherms, energy requirement, equilibrium moisture content, maturing coconut

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Bacteriocin production by Enterococcus faecalis VRE 1492 using different media at varying pH and temperatures


Author: Julie D. Tan

Abstract

Bacteriocins arc natural proteinaceous bactericidal substances produced by certain strains of bacteria and act against some other strains of the same or closely related species. This study was conducted to increase the level of bacteriocin production by Enterococcus faecalis VRE 1492 using selected growth media. Results showed that bacteriocin production by Enterococcus faecalis VRE 1492 was increased at different growth media, initial pH and fermentation time. Maximum production of bacteriocin was observed using De Man Rugosa and Sharpe (MRS) medium with glucose. The activity of bacteriocin was greatly increased in MRS medium with glucose at initial pH of 7.50 and 8.50 after 8 to 20 hours of fermentation at 30°C. Progressive increase in cell count from 0 to 24 hours of fermentation did not necessarily favor an increase in bacteriocin activity. After 20 hours of fermentation, the activity of bacteriocin decreased. The production of proteolytic enzymes by the bacterium was believed to inactivate the bacteriocin.

Keywords : bacteriocin, biopreservation, Enterococcus faecalis VRE 1492

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Influence of leaf volatiles of Eucalyptus citriodora Hook. on the growth and development of Exorista bombycis (Louis)


Author: K.C. Narayanaswamy

Abstract

The study evaluated the influence of olatiles emanating from crushed leaves of Eucalyptus citriodora Hook. on the growth and development. of uzi fly (Exorista bombycis Louis), a serious endoparasitoid of silkworm (Bombyx mori Exposure of freshly laid eggs of E. bombycis (Louis) to volatiles from the leaves of E.citriodora Hook. for different durations resulted in significant reduction in their hatchability. None of the maggots emerged from the host larvae when the eggs of the parasitoid were x posed for 64 and 74 hours to the volatiles. There was a significant increase in the duration of the life cycle aside from the reduction in the rate of pupation and adult emergence as the egg exposure period increased. Findings indicate that the chronic effects of volatiles were sustained during embryonic development. The known major chemical components of E. citriodora such as citronellal cineole, pinenes, pinocarveol, cuminaldehyde, sesquiterpene alcohols, aromadendrene, phenols and aldehydes are presumed to be responsible for its adverse effects on E. bombycis.

Keywords : Exorista bombycis. Eucalyptus citriodora, growth and development. leaf volatiles.

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Estimation of leaf area in two abaca (Musa textiles Nee) varieties by regression methods


Author(s): Ricardo A. Esplanada Jr. and Romel B. Armecin

Abstract

A rapid, non-destructive and precise method for leaf area (LA) determination in two varieties (Inosa and Laylay) of abaca (Musa textiles Nee) was developed from linear measurements. Combining both length (L) and width (W) in the model could predict accurately the actual leaf area of abaca. The regression equations that gave the modest mate for leaf area were LA = 1733.01 + 0.58 (L x W) (r = 0.87) for Inosa and, LA = -106.74 + 0.81 (L x W) (r = 0.99) for Laylay variety. Total leaf area can be estimated using leaf number 3 (third leaf below the newly expanded leaf) and leaf number 1 (newly expanded leaf) for lnosa and Laylay varieties. respectively.

Keywords : leaf area. linear measurements. Musa textiles.

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Evaluation of stability in sweetpotato using different methods


Author(s): S.K. Naskar and Archana Mukherjee

Abstract

The stability in sweetpotato (Ipomea batatas L.) was evaluated using the methods of Eberhart and Russel (1966), Shukla (1972.) and Francis and Kannenberg (1978). Eight sweetpotato lines along with a check local cultivar were grown for three years in eight environments across Orissa. India. Variances due to genotypes, environments, and genotype environment interaction were highly significant. Both linear and nonlinear components were also significant. The three stability method differed in identifying stable cultivars. Eberhart and Russel’s S2d and Shukla’s S2parameters were highly correlated (r2=0.78**). Only one genotype (90/606) was found stable under the three methods evaluated. The Francis and Kannenberg technique was most convenient in grouping the cultivars.

Keywords : coefficient of variation. G x E interaction. rank correlation. stability. sweetpotato.

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Effect of NaCl on axillary shoot proliferation in sweetpotato


Author: Archana Mukherjee

Abstract

Micropropagation through axillary shoot proliferation is a simple technique which ensures genetic stability of the propagules. To enhance the rate of multiplication, different doses of sucrose and NaC1 were used for axillary shoot proliferation in sweetpotato. Murashige and Skoog’s basal medium supplemented with growth regulators [NA A (0.5 mg/l) + BA (1.0 mg/l) + GA, (0.5 mg/l)] and variable doses of sucrose and NaCl were used. Among the different doses tested, 4% sucrose resulted in minimum bud dormancy. However, the overall shoot multiplication rate was optimal with 3% sucrose. Although the time required to bud break was considerably stable up to 0.5 g/l of NaCl supplementation and with 3% sucrose, the mean number of shoots produced per explant improved (3.5 — 5.5 shoots/ex-plant) with increasing NaCl level up to 1.0 g/l irrespective of the genotype tested. High rate of multiplication with supplementation of 1.0 g/I is significant for in vitro multiplication and also to use axillary meristem as target tissue for genetic transformation. Delayed bud break response with 2.0 g/l NaCl supplementation can be exploited for in vitro storage of sweetpotato.

Keywords : axillary shoot proliferation. growth regulators. sodium chloride. sweetpotato.

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