Category Archives: Volume 20 (1998)

Research Note: Common fungal diseases of native butterfly orchids (Phalaenopsis sp.)


Author(s): Marylene B. Posas and Manuel K. Palomar

Abstract

Specimens of the most common fungal diseases of native butterfly orchids were collected in Baybay, Leyte and the diseases and their casual organisms were also identified. Sclerotium rolfsii Sacc. Grew radially showing profuse, white, aerial, straight mycelia and brown sclerotial bodies in potato dextrose agar (PDA). Colletotrichum sp. exhibited creeping, whitish, straight mycelia with circular growth and produced abundant spores. Sporulation was observed after two days of growth in PDA. Phytophthora sp. showed suppressed growth and did not sporulate in PDA; it displayed creeping, whitish cottony mycelia with radial growth pattern. However, abundant sporangia were produced in onion agar (OA) and after immersion in sterile water for 2 to 4 days under laboratory condition. Incubation periods of S. rolfsii, Colletotrichum sp. and Phytophthora sp. were observed 2-3days , 10-11 days 9-12 days, respectively, after inoculation. Yellowish intact rotted portions characterized the disease caused by S.rolfsii while circular to oblong, sunken, necrotic lesions were produced by Collectotrichum sp. Watersoaked lesions incited by Phytophthora sp. gradually turned blackish and sunken with irregular border and shape. Of the three fungal pathogens, S. rolfsii was the most destructive with the highest severity.

Keywords : butterfly orchids . fungal diseases.

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Important cultural and management practices for coconut


Author(s): Rebecco M. Santiago and Janet T. Peña

Abstract

This paper discusses some important cultural and management practices for coconut specifically fertilizer application, covercropping, intercropping and pasture and cattle raising under coconut. Fertilizer application improves seedling growth, enhances maturation and increases nut production of coconut. Covercropping is a good cultural practice because it minimizes soil compaction, erosion and other degradation processes that lead to the early marginalization of coconut lands.
Intercropping is not injurious to the coconut provided that the nutritional and cultural requirements of both the main and subsidiary crops are properly observed. Under good management, intercropping in coconut is a profitable venture. Growing of pasture crops and cattle under coconut is another way of maximizing the use of coconut land as well as of augmenting farmers’ income, provided that improved management techniques are also employed.

Keywords : cattle raising . coconut covercropping . fertilizer application . intercropping pasture.

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The water yield of Molawin watershed as influenced by rainfall, physiographic and anthropogenic factors


Author(s): Arturo E. Pasa1 and Teodoro R. Villanueva2

Abstract

A study was conducted to determine the effects of rainfall, physiographic and anthropogenic factors on the water yield of Molawin watershed. Results showed that the total suspended solids was increased by the tractive force of streamflow and the activities of the people inside the watershed. Rainfall increased the streamflow volume but showed delayed response in the later part of the study.
The volcanic mud spring also decreased the water quality on the upper portion of the watershed. The emission of grayish mud from the mud spring caused high total suspended solids and turbidity of the river water. This natural condition could have also caused the low pH and chemical oxygen demand of water at the fifth station. The lower portion of the watershed, on the other hand, showed low dissolved oxygen but with high chemical and biological oxygen demands.
This study concluded that the continued influx of people into the watershed would further degrade the water quality and could cause unwanted streamflow fluctuations. Maintaining the present vegetation and controlling human activities are recommended.

Keywords : watershed . water quality . water regimen . water yield

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Doubling macapuno seedling production through embryo splitting


Author: Tessie C. Nuñez

Abstract

A simple means of deriving two seedling from a hybrid macapuno embryo was developed. Macapuno embryos were allowed to grow in vitro for 1 to 1.5 months or until the shoots and roots emerged. Germinating embryos were cut longitudinally, equally dividing the shoots and roots. Split embryos were then subcultured in an appropriate medium until seedlings were fully developed and ready for potting.
During the first month in culture, 82% of the embryo halves development normal shoots and roots. After the first month, however, only 2 pairs of split embryos had both halves developing normally. Others had only one of the halves producing a complete plantlet while the other pair died.
The first potted seedling grown from a halved embryo had 5 leaves and 5 primary and adventious roots with plenty of root hairs during potting at 7.5 months after initial culture. It was 22 cm long with a base diameter of 1.4 cm.

Keywords : coconut . macapuno . embryo culture . embryo splitting.

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Pigeonpea intercropping with some cereals and legumes in the plateau area of Eastern India


Author(s): S. Adhikary, P. Banik and P.K. Ghosal

Abstract

Field experiments were conducted during the rainy seasons of 1992-93 and 1993-94 at the agricultural experimental farm, Giridih, Bihar to evaluate the intercropping system of pigeonpea (Cajanus cajan L.) with cereals such as maize (Zea mays L.) and rice (Oryza sativa L.), and legumes such as greengram (Phaseolus radiates L.) and groundnut (Arachis hypogaea L.). Pigeonpea + groundnut was the best system followed by pigeonpea + greengram with pigeonpea equivalent yields of 2.51 t ha-1 and 2.07 t ha-1, respectively, compared with 1.97 t ha-1 from pigeonpea alone. The efficiency of intercrops was assessed on the basis of actual yield loss where yield per plant of the component crop was considered. Soil nitrogen enrichment through legume cultivation contributed to higher yield of the succeeding Indian mustard crop (Brassica juncea L. Crenz & Cosson).

Keywords : competition function. follow-up crop. intercropping . residual soil nutrients.

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Root development of coconut reciprocal crosses and their parental cultivars at early bearing stage


Author(s): Tessie C. Nuñez and Dario P. Lina

Abstract

To understand the influence of parent coconut cultivars on the root development of their hybrid, this study was conducted in Inopacan, Leyte using eight dwarf and tall reciprocal crosses and their parent genotypes.
Coconut crosses with dwarf (D) and tall (T) parents were found to have lighter roots than the tall parents but had heavier roots than the dwarf parents. Significant differences in root weight of reciprocal crosses were observed in some sampling points in specific cross combinations. However, these were not general trends for D x T and T x D crosses.
Generally, crosses involving Baybay Tall had more roots which were distributed wider and deeper in the soil than crosses with Puringkitan as one of the parents.

Keywords : coconut. reciprocal hybrids. root development

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The importance of trees for the survival of the poor in Annangland, Nigeria


Author: Maurice Akpan Okoji

Abstract

Per capita income is low in Nigeria. In some rural areas it is below US$30.00. This level of income has forced the rural poor to rely on accessible natural resources for survival. To find out the role of trees in this regard, six villages in each of the six local government areas of Annangland were studied. Fifteen households were interviewed per village, using the participatory rapid appraisal method of data collection. It became clear that the rural poor in Annangland planted trees and protected self-sown trees for commercial, medicinal, social and agricultural reasons in addition to varying their diets. Some policy measures are considered for pusposes of conserving resources upon which the poor depend and of revisiting relevant regulations and traditions in the interest of the rural poor.

Keywords : natural resource conservation. participatory rapid appraisal. rural poor. trees.

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