Assessing yield losses in sweet potato due to the weevil, Cyclas formicarius Fabr. [Philippines]
1985
Corey, F.M. Jr. | Cadapan, E.P. (Bureau of Plant Industry, Cebu City (Philippines). Regional Crop Protection Center)
The relationship of marketable yield with different indicator variables such as weevil density in the main stems and roots, percent weevil rating and percent weevil damage in the tuberous roots in the first and second croppings were tested by correlation and polynomial regression analysis. All indicator variables were highly negatively correlated with marketable yield of sweet potato, indicating a strong evidence of association. Although the indicator variables afforded high coefficients of correlation (4) and determination (r2) only two of them, namely, percent weevil rating and percent weevil damage, provided the highest and consistent coefficients. These two variables therefore, are more reliable indicators in assessing yield losses due to weevils. However, the percent weevil rating as an indicator variable for estimating yield losses due to weevil infestation, was more convenient and practical. The estimated percent yield loss was computed based on the formula: Y=-.292 + 1.905X - .009X to the second power
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