Category Archives: Volume 18 (1996)

Effect of multiple mating on reproductive in three popular races of silkworm Bombyx mori L.


Author(s): P.J. Raju, Mahadevappa, D. Guruswamy, R. Raghuraman and S.B. Dandin

Abstract

Economics of egg production is vital for grainages since it is a commercial preposition which necessitates recovery of maximum number of laying with high fecundity. Attempts have been made to increase reproductive rate by multiple mating in Pure Mysore (PM), a multivoltine race and Kalimpong-A (KA) and NB4D2 , the bivoltine races of silkworm Bombyx mori L. The studies revealed increase in egg laying coefficient for multiple-mated moths of all three races. The possible mechanism in multiple mating which stimulates oogenesis and thereby reproductive rate is discussed.

Keywords : Bombyx mori L. Fecundity. Multiple mating.

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Racial differentiation of α- and ß- esterase isozymes in selected races of silkworm Bombyx mori L.


Author(s): R.S. Umakanth and N.B. Krishnamurthy

Abstract

Isozymes of α- and β-esterases were analyzed in four selected races of univoltine (B38P), bivoltine (NB18 and SF19) and multivoltine (C.nichi) by employing polyacrylamide gel electrophoretic technique (PAGE). Racial differences as a reflection of ontogenic differentiation of the multi-banded system in the races under study were identified, although the trend of differential activity of the esterase(s) follows a specific pattern in all the races. Certain differences are also known between α- and β-esterases is more prominent and exhibits higher activity.

Keywords : Bombyx mori. Esterases. Isozymes. Ontogeny. PAGE. Voltinism. Zymogram.

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Improvement of the farmers’ direct-type copra dryer


Author(s): E.E. Sudaria and R.V. Piedraverde

Abstract

A survey on the farmers’ direct-type tapahan copra dryer was conducted to monitor the configuration of the dryer, depth of heat source, fuel consumption and time of drying. Three copra dryers with square, parabolic, and rectangular pit configurations were constructed and evaluated at varying depths of heat source of 2.3 m, 1.8 m, and 1.3 m. the performance of the farmers’ copra dryer using the 1.67 m average depth of heat source was compared to the performance of the dryers under study.
Results showed that the square dryer at 1.8 m depth performs significantly better compared to the other types of dryer at different depth levels and the farmers’ tapahan dryers. It has the shortest average drying time of 8.67 h, lowest average fuel consumption of 566.67 husks, and highest averages in drying rate and drying rate per unit fuel consumption of 31.08 kg/h and 0.137 kg/h-kg, respectively. The copra color produced was similar regardless of dryer type.

Keywords : Coconut farmers. Copra dryer. Improvement. Tapahan.

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Mangrove floral composition and zonation in Western Leyte


Author(s): R.F. Sebidos and M.I. Galinato

Abstract

Mangroves are a community of trees or shrubs thriving along tidal flats and coastlines extending inland along rivers, streams and their tributaries with brackish waters. A floral composition survey identified 14 species of true mangrove trees belonging to 8 families, and 11 associated species in 10 families, present in 12 different towns of W. Leyte. Mangrove communities within and between sites markedly differ in their zoning pattern. In the northern part Sonneratia dominated the seaward edges while Avicennia in the landward fringes. However, in the southern part Rhizophora is found in the seaward edge while a mixture of Sonneratia, Ceriops and Avicennia occupied the landward zone.

Keywords : Brackish water. Mangrove. Tributaroes. Zonation.

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Inhibitory and stimulatory effects of root exudates in two varieties of rice


Author(s): S. Mandal, P.K. Tapaswi, R.N. Banerjee and R.L. Brahmachary

Abstract

The (allelopathic) interaction between two varieties of rice (Oryza sativa) seedlings Subarna and Pankaj was studied. Root exudates (RE) of Subarna inhibit the germination and growth of seedlings of Pankaj and vice-versa. RE of both Subarna and Pankaj contain phenolic compounds, amino acids and presumably a fatty acid. The putative fatty acid appears 15-20days following germination and disappears after two months. Only one phenolic was detectable in the later stages and two others in young seedlings. The Rf values of these three putative phenolics show that none of these is among the eight standards, namely: syringic acid, caffeic acid, ferulic acid, 3-4 dihydroxy benzoic acid, vanillic acid, 4-hydroxy benzoic acid, coumaric acid, and sinapic acid. The synergistic effect is inhibitory but when chromatographically separated two inhibitors and three stimulators have been found in RE of two-month old subarna.

Keywords : Allelopathy. Phenolics. Rice (Oryza sativa). Root exudates.

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Efficacy of Paecilomyces lilacinus isolates for the control of root-knot nematode (Meloidogyne incognita [Kofoid and White] Chitwood) in sweetpotato


Author(s): C.D. Galano, R. M. Gapasin and J.L. Lim

Abstract

The application of different Paecilomyces lilacinus isolates grown in water hyacinth substrate, 50 days after Meloidogyne incognita egg inoculation increased fresh vine and fibrous root weights by 32.6-36.2% and 29.6-35.1%, respectively over the untreated control. On the other hand, chicken manure and ethoprop (Mocap)-treated plants had an increase of 37.9-43.0% and 18.6-29.9%, respectively.
The mean number of root galls, egg masses produced and nematode population in fibrous roots and soil in plants applied with P. lilacinus isolates ranged from 27.8-42.0, 40.9-58.1, 8.4-11.5 and 392.0-800.8, respectively. The isolates evaluated for their efficacy gave comparable effects since no significant differences in effect were observed among them. Chicken manure-treated plants had a mean number of root galls of 28.8 and egg masses of 40.3 showing an egg mass reduction of 55.7%. Ethoprop gave the lowest number of galls (4.2) and egg masses (6.2) among the treatments. Percent reduction based on egg masses produced was 93.2 relative to the untreated control.
The overall results of the study showed that the efficacy of P. lilacinus in reducing root-knot galls, egg masses and nematode population was comparable to chicken manure but not with ethoprop.

Keywords : Chicken manure. Egg masses. Ethoprop. Galls. Ipomoea batatas. Meloidogyne incognita. Paecilomyces lilacinus. Root-knot nematode. Sweet potato.

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Efficacy of selected fungicides against basal stem rot of wilt of tomato caused by Sclerotium rolfsii Sacc.


Author(s): L.M. Borines and C. V. Ranchez

Abstract

The efficacy of selected fungicides was tested against the basal stem rot or wilt of tomato caused by Sclerotium rolfsii Sacc. An in vitro assay of fungicides revealed that mancozeb (Dithane M-45) was the most effective in suppressing the colony growth and sclerotia formation of S. rolfsii. Manganese ethylene bisdithiocarbamate (Maneb) also significantly reduced the colony growth of the pathogen but its effectivity was lesser when heated. Captan (Captan) and thiophanate methyl (Fungitox) reduced growth to a lesser extent while benomyl (Benlate) reduced colony growth only when not subjected to heat.
Results of the field evaluation further proved the effectiveness of Dithane M-45 and Maneb in controlling sclerotium wilt in the field. These fungicides produced the lowest disease incidence and highest percent protection on the plants during the wet season and dry season trials. Fungitox was less effective than Dithane M-45 and Maneb while Belate was ineffective in controlling sclerotium wilt in the field.

Keywords : Basal stem rot wilt. Efficacy. Fungicides. Sclerotium rolfsii. Tomato.

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