EFFECTIVENESS OF SLOW-RELEASE INSECTICIDE (CHLORPYRIFOS 10% W/W) AGAINST SITOPHILUS ORYZAE (L.) (COL. CURCULIONIDAE) IN PACKAGED WHEAT I.2

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TEE SZE PENG

SUMMARY

Adult rice weevils, Sitophilus oryzae (L.) were exposed to-slow- releas cehlorpyrifos (10% w/w) dispensers of sizes 1.5, 5, 15, 20 and 25 cm2) in wheat packages . Complete mortality of adult weeviils resulted after 30 days exposure in the packages treated with dispenser measuring 20 and 25 cm2. However, oviposition was not prevented as F1, progeny of weevils continued to emerge betweed 30 and 60 days, but most of the progeny that emerged were dead whwn examined at 60 days. No significant loss in weight of grain was not in packages treated with 5 to 25cm2 dispensers between 60 and 90 days. However, in these treatments, initial grain by aduilt feeding and larval development between 30 and 60 days was significant. The potential used of the insecticide formulation for controlling insects of store grains seeds were discussed

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OVERSOWING OF STYLOSAN THE GUIANENSIS INTO NATIVE PASTURES: COMPARISON OF ESTABLISHMENT TECHNIQUES

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IZHAM AHMAD and HASSAN ABD. WAHAB

SUMMARY

Two experiments on low input techniques of oversowing Stylosanthes guianensis cv. Schofield (common stylo) for improvement of native pastures were conducted at Serdang on two tvpes of native pastures viz. Paspalum conjugatum (Paspalum) and Imperata cylindrica (Lallang). The first experiment (Paspalum area) involved trwo mowing treatments (mowing and no-mowing) and three seed placement techniques (broadcast, hoe and tining). In the second experiment (Lallang area), similar seed placement techniques were tested but with different mowing treatments (mowing and mowing + burning). In the Paspalum area, the establishment of common stylo was superior on mown plots and when the seeds were either placed on hoe depressions or along tined furrows. In terms of total dry matter (DM) yield harvested at two monthly intervals, there was no significant difference between the seed placement techniques. The average DM yield was 1130 kg/ha/2 months. After one year, the quality of the sward was greatly improved by the increase in the percentage of common stylo to over 60% in the hoe and tining methods of both prior to mowing treatments. The percentages of common stylo in the mowing-broadcast and no mowing-broadcast were 41 and 23%, respectively. For the lallang area, there was no significant difference in the germination counts between the three seed placement techniques except in the early establishment where the hoe technique was better than the broadcast method. There was also no difference in the number of surviving plants in either of the mowing treatments tested. After six months, the total DM yield in the mowing and mowing + burning treatments were 1263 and 1839 kg/ha, respectively. The corresponding percentages of common stylo were 11 and 22%.

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PHOSPHATE ADSORPTION CHARACTERISTICS OF SOME MALAYSIAN SOILS: CONFORMITY WITH ADSORPTIOMNC IDELS

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ABDUL RASHID AHMAD

Three adsorpation models, the Langmuir Freundlich and Tempkin, were used to the describe the phosphate adsorpation chareacteristics of some Malaysian soils. The Langmuir model was found to conform very well with the adsorpation date only for soils having very high adsorption capacity. The Freundlich model was found to conform very well with the adsorption data for soils having intermediate adsorption capacities. The Temkin model was found to improve the Langmuir model at a low range of equilibrium concentration and is thus useful for soils having high adsorption capacities. The parameters which summarie the adsorption process are the maximum buffer capacity (MBC) of the Langmuir model, the adsorption constant (a) of the Freundlich model and the contanst (q) of the Temkin model. Their use should be limited to the P concentration range within which the models conform with the adsorption data. By using parameters as characterizing parameters it was found that some Malaysian soil may be classified according to their adsorption capacity.

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SUSTABILITY OF FIVE PREEMERGENCE HERBICIDES FOR CASSAVA(MANIHOT ESCULENTA CRANZ)

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LO NYOK PIANG

SUMMARY

Two experiments were conducted to determine the suitability of five preemergence herbicides for cassava. The first experiment showed that alachlor [2-chloro-2', 6'-diethyl N-(methoxymethyl)- acetanilide], fluometuron [1, 1-dimethyl-3-(a, a, a-trifluro-m-toly) urea], and oryzalin (3. 5-dinitro-N4, N4-dipropylsulfanilamide) were safe to cassava at 1.5 kg/ha and produced a satisfactory weed control Applied at 1.5 kg/ha, diuron [3-(3, 4-dichlorophenyl)-1, 1-dimethylurea] induced some phototoxicityl tebuthiuron [N (5-(1, 1-dimethyl-ethyl)-1, 3, 4-thiadiazol-2-yl)-N, N-dimethylureal gave a long and excellent weed control but induced severe phytotoxicity. The second experiment confirmed that alachlor, fluometuron and oryzalin were selective and had a wide margin of safety to cassava. Diuron had been found to be partially selective and may not be safe if applied more than 1.5 kg/ha. However, it may be used in combination with alachlor at a reduced rate. It is concluded that suitable herbicides fbr cassava were alachlor, fluometuron and oryzalin

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MODIFIED ANION-EXCHANGE RESIN METHOD FOR SOIL PHOSPHATE DETERMINATION

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LEONG CHEE ONN

SUMMARY

The use of anion-exchange resins in soil phosphate determination w re investigated. Among the variables tested wre resin weight ,period of resin regeneration and phosphate elution soil: solution ratio and different extraction times. A final analytical procedure on the use of anion-exchange resins was then formulated based on the results of these studies.

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