Are we measuring what we think we are measuring? Recent experience in using DNA fingerprinting and implications for tracking varietal adoption and assessing impacts

Varietal adoption based on household surveys has mostly relied on farmers’ response to varietal identification. This method can give biased estimates if farmers are unable to identify improved varieties as a group or by name, or give names that do not match with the improved variety list. To tackle these potential problems requires time intensive data collection such as including follow-up questions in the survey instrument, visiting the field to observe plant characteristics, or collecting sample materials (i.e., photos, seeds/plant tissues) from the farmers for later verification by experts. Each of these approaches has implications on the cost of data collection and the accuracy with which they can correctly identify a variety. This paper reports the results of two pilot studies conducted in Ghana and Zambia to test different approaches of collecting variety-specific adoption data, and to validate them against the benchmark of DNA-fingerprinting to determine which method is most effective in measuring varietal adoption. Results suggest large variations in the estimates of adoption rates obtained by these different methods, compared to DNA fingerprinting results. This paper also highlights some potential challenges of varietal identification when multiple released varieties are discovered to be essentially the same based on the DNA fingerprints or when released varieties share the same DNA fingerprint as some landrace materials included in the reference library. The Implications of these results on the effectiveness of alternate methods of varietal identification, including DNA fingerprinting are discussed.