Variation of grain iron content in a local upland rice germplasm from the village of Huai Tee Cha in northern Thailand

Crown rust caused by Puccinia coronata Cda. f. sp. avenae Eriks., is a major fungal disease of cultivated oats (Avena sativa L.) in Tunisia. Six landrace oats (M_tK₂, JT₅, BJ₃₅, GT₁, ZN₃ and JT₀) locally collected and previously screened for their relative oat crown rust resistance were used in this experiment. These accessions were evaluated during a two cropping season in field plots under heavy natural oat crown rust infection. Assessment criteria to crown rust reactions were AUDPC, latent period, uredinia size and number of uredinia per cm² of infected leaf area. Principal components analysis showed that the variables were grouped in two components. These two principal components explained 83.56% of the total variance. The projection of the point-cloud representing the populations on the plan formed by the principal components ‘Fact 1’ (63.83%), in abscissa, and ‘Fact 2’ (19.73%) in ordinate, permitted to distribute the accessions in several groups. Three landrace oats (M_tK₂, JT₅, and JT₀) showed the lowest value of all the components used. These landrace oats might be good sources of effective and durable resistance to crown rust.     

Effect of <Emphasis Type="Italic">Metarhizium guizhouense</Emphasis> infection on mating competition and mate choice of <Emphasis Type="Italic">Bactrocera latifrons</Emphasis> (Diptera: Tephritidae)

Metarhizium guizhouense PSUM02 treated males of Bactrocera latifrons were investigated for the mating competition among males and mating choice by female flies to develop an auto-dissemination for the control of B. latifrons. In the present study, on day 1–4 of experiment, M. guizhouense–treated male flies were equally competitive with the normal male flies as we did not observe any differences in mating by treated and normal male flies of B. latifrons. Further, mating competitiveness were found low in treated adult male B. latifrons than normal male B. latifrons from 5th days of treatment until death. Kaplan-Meier survival analysis of treated male flies gave average survival times (AST) of 4.3?±?0.1 days, while the healthy female and male flies in the same cage showed AST of 9.3?±?0.3 and 8.3?±?0.4 days, respectively. The AST of untreated flies in control experiment ranged from 14.2–14.5 days. In mating preference experiment, M. guizhouense–treated male flies were chosen by virgin female than gravid female flies for mating. The treated male flies caused mortality in both virgin and gravid female flies in the same cage with AST of 4.4?±?0.1, 5.6?±?0.1 and 7.4?±?0.2 days, respectively, while untreated flies showed AST ranged from 13.9–14.3 days in control. The treated male flies could transmit the fungus infection to both untreated female and male flies as well as in virgin and gravid female flies by mating and contact. Our experiments showed the potentiality of M. guizhouense PSUM02 in management of B. latifrons by auto-dissemination with treated male flies, which transmit the fungus to a healthy population to reduce insect pest infestations.     

Fallow enrichment with pada (Macaranga denticulata (Bl.) Muell. Arg.) trees in rotational shifting cultivation in northern Thailand

Shifting cultivators in Thailand widely attribute the maintainance of crop productivity to pada (Macaranga denticulata (Bl.) Muell. Arg.), rotation cycles having become much shorter than the customary 10–20 years. This paper examines the use of pada in a 7-year rotation on an acid soil with low available soil P (2–4 mg kg^–1 by Bray II). Dense pada patches in 7-year-old fallow averaged 43 tons ha^–1 of above ground biomass, 20% more than sparse patches. The biomass in dense pada contained disproportionately more P, K, Ca and Mg (34%, 92%, 80% and 107% more, respectively) than in sparse pada patches. Slashing and burning 7-year-old fallow with dense pada produced a subsequent rice yield that was three time that with sparse pada. Rice grown after dense pada had been slashed and burned after three years yielded less than one third of that after a full 7-year rotation. It is, as yet, unclear how rice yield in dense pada patches is enhanced in the full 7-year rotation. Nutrient concentrations in the mature rice were generally either the same or higher in the sparse than dense pada patches. In dense pada patches rice accumulated twice to four times as much nutrients as in sparse pada patches, and a much larger fraction of the nutrients was stored in the fallow. Uptake of nutrients in the sparse pada patches may have been limited by some factor that either governs availability of the nutrients released by burning or depressing rice growth and so its nutrient demand.This revised version was published online in November 2005 with corrections to the Cover Date.     

Land use transformation in the mountainous mainland Southeast Asia region and the role of indigenous knowledge and skills in forest management

The mountainous mainland Southeast Asia region, that covers adjoining parts of Cambodia, Lao PDR, Myanmar, Thailand, Vietnam and China, contains the region's largest remaining tropical forest. The people living in the forested mountains, who belong to a diversity of ethnic minority groups, possess a wealth of local knowledge and skills in forest management. With rapid decrease in forest area, implementation of forest conservation policies, improved access to market and replacement of shifting cultivation with permanent cropping, land use and management in the region has been rapidly changing. Some indigenous knowledge and technology in forest management will inevitably continue to be lost in the process, but not all. This paper shows how local forest management systems have been adapted to deal with the change, with specific focus on deployment and adaptation of indigenous knowledge and skills. First background on the region and its traditional land use systems will be provided. A review will then be made of the cropping system changes that have been taking place and their driving forces and how local farmers have adapted indigenous knowledge and skill in forest management to meet current needs and conditions. Cases drawn from studies in the region will illustrate how deployment of indigenous technology not only helps the farmers to improve their productivity but can also provide services in forest regeneration and biodiversity conservation. To do this farmers, including those who were former migratory opium growers, make use of the knowledge of their own environment and locally available genetic resources and the community's organizational and management skills. It will also be shown that farmers’ knowledge and skills are not static, but continually revised and integrating modern inputs as well as transfer of new ideas and innovations.