Abstract
This paper attempts an empirical assessment of the incentive effects of plant variety protection regimes in the generation of crop variety innovations. A duration model of plant variety protection certificates is used to infer the private appropriability of returns from agricultural crop variety innovations in the UK over the period 1965-2000. The results suggest that plant variety protection provides only modest appropriability of returns to innovators of agricultural crop varieties. The val- ue distribution of plant variety protection certificates is highly skewed with a large proportion of innovations providing virtually no returns to innovators. Increasing competition from newer varieties appears to have accelerated the turnover of varie- ties reducing appropriability further. Plant variety protection emerges as a relatively weak instrument of protection.
