摘要：The aims of our paper are to identify economic determinants of the on-farm cultivars diversity and to empirically characterize the farmers' diversification choices. We focus on the private decision making process involving the choice of rice cultivars and the corresponding allocation of farmland. For a specific crop, the choice of cultivars, and the resulting cultivars portfolio, involves the farmer comparing benefits and costs. Among the many costs involved, we focus on diversity's management costs. Our results rely on original data collected during the spring 2009 in the study area, and involve a sample of 86 economic units growing rice. We estimated a count data model, in which the endogeneous variable is the number of cultivars grown on the farm. After that, we studied the factors explaining the portfolio choice in terms of commercial rice grain, and the on-farm repartition between these different types. A multinomial logit model was used, with three alternatives, be specialized into a particular type of rice grain (long or round), or grow simultaneously these two types, or finally be diversified with niche market varieties. And finally we estimated the percentage of long rice compared to the percentage of round rice with a linear regression model. The results confirm the importance of the interactions between market related benefit and the management constraints on land and labor.
