Relationship between NDVI and Cassava Productivity in Kamphaeng Phet Province

Abstract

The normalized difference vegetation index (NDVI) is remote sensing measurement which has been used to measure and monitor plant growth, biomass production and vegetation cover. The technique was employed in this study to estimate the relationship study area of Kamphaeng Phet province, represents a large cassava growing area dominated by a single cultivar. Rayong 5 is the most adopted cultivar and farmers generally grow and harvest one or two years after planting. Six groups of cassava were then classified by variety as well as growing duration for this study :-1) Rayong 5, not harvest 2) Rayong 5, one year harvest 3) Rayong 5 two years harvest 4) mixed varieties, not harvest 5) mixed varieties, one year harvest 6) mixed varieties, two year harvest. A simple linear correlation and regression was applied to explain the relationship between NDVI and surveyed yield. The results revealed a positive correlation between NDVI and fresh root yield of Rayong 5 and mixed harvested one year after planting. The significant relationship was found only for NDVI acquired in November 2009 for Rayong 5 and November and December 2009 for mixed varieties. In contrast, the insignificant relationship was found for cassava being grown and harvested more than one year after planting for all NDVI. Although the NDVI showed a positive relationship with actual yield there was insignificant relationship pattern indicating cassava yield. It is shown from this study that the NDVI acquired in November 2009 could be the variable predicting cassava yield harvested in one year. Future studies should be focused on other predictor variables, such as NDVI at the maximum leaf area index or above ground plant dry weight of cassava and other vegetation indices.