An analysis of the relation between dry matter allocation to the tuber and earliness of a potato crop.

Compared with late cultivars, early potato cultivars allocate a larger part of the available assimilates to the tubers early in the growing season, leading to shorter growing periods and lower yields. A dynamic simulation model, integrating effective temperature and source –sink relationships of the crop, was used to analyse this relation, using data from experiments in the Netherlands carried out over 5 years. Dry matter allocation to the tuber in these field experiments was simulated well when the tuber was considered as a dominant sink that affects earliness of a potato crop in two ways: early allocation of assimilates to the tubers stops foliage growth early in the season and reduces the longevity of individual leaves. In a sensitivity analysis the influence of tuber initiation, leaf longevity and the maximum relative tuber growth rate (Rtb) on assimilate allocation and crop earliness was evaluated. It was found that the maximum relative tuber growth rate can influence crop earliness more than the other two factors, but when conditions for tuber growth are optimal, the leaf longevity is most important.