東北タイにおけるキャッサバ生産力のGISによるマッピング Mapping of Cassava Productivity Using GIS in Northeast Thailand

Access this Article

Author(s)

Abstract

東北タイにおける, 主要畑作物キャッサバの生産性を, 作物モデル, 資源データベース及びGISツールを用いて地図化した.気温と日射量のみを制限要因とする潜在収量の20年平均の分布図により, 東北タイ全域でキャッサバの潜在収量は高く, 地域内変動が小さいことが明らかになった.また, 年変動も全域で小さかった.一方, 気温と日射量に加えて, 水条件 (土壌水分または湛水深) を制限要因とする達成可能収量は, 全域で潜在収量より小さかったが, 低地部 (氾濫原と丘陵低位部) では湛水が, 中高地部 (丘陵中高位部) では水ストレスが, 潜在収量を低下させる主因となっていた.達成可能収量は, 地域内変異が大きく, 中高地部が低地部より高かった.また, 達成可能収量の年変動は, 低地部で大きく, 中高地部で小さかった.このことから, 東北タイ中高地部では, 栽培管理が適正であれば, 比較的高く安定したキャッサバ生産が期待できることが明らかとなった.1997年の実収量と達成可能収量の比較により, 殆どのキャッサバ生産地で, 達成可能収量が実収量を相当上回ることが示され, 東北タイのキャッサバ生産には集約化による生産力向上の余地が十分にあることが示唆された.

Potential and attainable yields of cassava in Northeast Thailand for the past 20 years were mapped using a crop model, resources databases and GIS tools. Potential yields of cassava reflected the potential productivity with air temperature and solar radiation as limiting factors, and the map of average potential yields indicated that the potential productivity of cassava was relatively high in this area with a high stability and small regional variations. On the other hand, attainable yields, which included the additional limiting factor, i.e. water conditions, and indicated the potential of cassava productivity under rain-fed conditions, were lower than potential yields in most areas of Northeast Thailand. Waterlogging and water stress were the main factors responsible for the reduction of attainable yields in the lowlands and mid-highlands, respectively. In the contrast to the potential yields, attainable yields showed large regional variations and higher attainable yields were observed in the mid-highlands than in the lowlands. In the lowlands, yearly variations of attainable yields were very large, whereas small in the mid-highlands. This suggested that relatively high and stable yields could be achieved in mid-highlands in Northeast Thailand if appropriate cultivation management were to be applied. Comparison of the maps of actual and attainable yields in 1997 indicated that in most of the cassava-producing areas actual yields were much lower than attainable yields, suggesting that there is enough room for the improvement of cassava productivity by the intensification of cultivation methods.

Journal

  • Japanese Journal of Tropical Agriculture

    Japanese Journal of Tropical Agriculture 48(4), 211-219, 2004

    Japanese Society for Tropical Agriculture

Codes

Page Top