Category Archives: Volume 9 No. 4 (1987)

Note: Effect of Sett Type on the Performance of Tugui [Dioscorea esculenta (Lour) Burk.]


Author(s): Alfredo G. Dingal, Nestor L. Pido and Daniel G. Ecleo

Abstract

Sett type of tugui [Dioscorea esculenta (Lour) Burk.] could be arranged in order of increasing mortality and decreasing yield as follows: wholes, heads, tails and middles. Whole setts and middle setts had the highest and the lowest percentage emergence, respectively. The inability of some setts to germinate was attributed to tuber rot that resulted in death of setts. The number of sprouts did not differ among sett types but yield significantly differed mainly due to differences in mortality among sett types.

Keywords : tugui [Dioscorea esculenta (Lour) Burk.] . Sett type. Emergence. Mortality. Sprout. Tuber yield.

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Mathematical Models for Predicting Kiln-Drying Time and Modifying Kiln Schedules for Some Philippin Hardwoord Species


Author(s): A.P. Bangi, E.D Bello and G. Bramhall

Abstract

Three models based on Bramhall’s drying-effort method for calculating kiln-schedule modifications were developed to determine the reliability of the method to the kiln drying of some Philippine hardwood lumber species. The general form of the models is based on Bramhall’s vapor-pressure gradient concept of bound-water diffusion, and is basically dependent on empirically determined relationships between the resistance-to-drying (R) and the average charge moisture content (M). Functional R-M relations were established for three species-thickness combinations of Philippine hardwoods using simple linear regression techniques. In all cases, an exponential relationship of the form R = A exp (-bM) was observed. Chi-square tests on several comparisons between predicted and observed drying times showed that the models are sufficiently valid and accurate at 5% level of significance. The models are best fitted to the species-thickness combinations tested but it appears that they are also applicable to the kiln drying of mixed kiln charges involving other lumber species of comparable wood density.

Keywords : Drying-effort method. Resistance-to-drying. Kiln-drying time. Kiln charge. Kiln runs. Kiln schedule. Species-thickness combination. Mix-drying

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Factors Affecting the Rate of Fusarium Rot Development in Harvested Tomato Fruits


Author: Crisanta E. Sajise

Abstract

The effects of storage temperature, moisture, packaging material and duration of exposure to inoculum on the development and severity of Fusarium rot on tomato fruits were investigated. Apparent infection rate and disease severity values were significantly higher at room temperature (27.5°C). However, disease development was completely inhibited at 10°C but most favored by moist condition. Severity and spread of disease increased with longer exposure to inoculum. Sealed polypropylene bags gave the utmost protected of tomato fruits against F. moniliforme infection.

Keywords : Tomato. Fusarium moniliforme Sheldon. Apparent infection rate. Disease severity. Inoculum

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Effects of Decamethrin and Permethrin on the Biology of Two Coccinelid Predatos of Black Bean Aphids


Author(s): Erlinda A. Vasquez, Emiliana N. Bernardo and Lorenza B. de Pedro

Abstract

The two species of coccinellid predators (Chilomenes sexmaculata Fabr. and Coleophora inaequalis Fabr.) treated with decamethrin and permethrin showed slightly longer total developmental period, higher mortality rate and lower fecundity rate than the untreated ones, particularly C. inaequalis. No significant differences were found in percent egg hatchability and adult longevity. These results were observed only in the first generation where individuals were in direct contact with the insecticides but not in the second and succeeding generations.
Data generally suggest that decamethrin is relatively safe to the two species of predators and that decamethrin-coccinellid combination could be recommended for black bean aphid control.

Keywords : Decamethrin. Permethrin. Coccinellid predators. Biology. Black bean aphids.

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Effect of Delayed Processing on Alcohol Yield of Fresh Root Crops


Author(s): Edgardo E. Tulin and Emma S. Data

Abstract

Delayed processing significantly affected the starch and total sugar contents of cassava and sweet potato roots. However, these is no apparent trend to show the relationship between delayed processing and starch or sugar content of the roots.
Alcohol production was significantly influenced by late processing in sweet potato but not in cassava. The highest alcohol content was obtained from sweet potato roots processed 2 days after harvest and fermented for 96 hours. In cassava, the amount of alcohol produced did not significantly vary even if the roots processed were fresh or stored up to 5 days under ambient conditions.

Keywords : Delayed processing. Cassava. Sweet potato. Alcohol production. Fermentation. Alcohol yield. Total sugar. Starch

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Effects of Land Preparation and Postplanting Tillage on Weed Control and Cassava Yield


Author(s): Federico G. Villamayor, Jr. and Veronica L. Reoma

Abstract

Two experiments were conducted to determine the effect of land preparation and postplanting tillage on weed control and cassava yield. The first experiment showed that weed biomass and cassava yield were not affected by the method of land preparation. Postplanting tillage, however, significantly affected weed biomass and root number but not root yield.
The best three postplanting tillage treatments in the first experiment based on costs and returns, were further tested in a second experiment. Tillage involving off-barring 2 weeks after planting (WAP) followed by handweeding within the row 3 WAP and hilling-up 5 and 7 WAP gave the highest yield and net return.

Keywords : Cassava. Land preparation. Postplanting tillage. Wee control. Cassava yield

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