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 r elationships of the crop, was used to analyse this relation, using dat a from experiments in the Netherlands carried out over 5 years. Dry ma tter allocation to the tuber in these field experiments was simulated well when the tuber was considered as a dominant sink that affects ear liness of a potato crop in two ways: early allocation of assimilates t o the tubers stops foliage growth early in the season and reduces the longevity of individual leaves. In a sensitivity analysis the influenc e of tuber initiation, leaf longevity and the maximum relative tuber g rowth rate (R(tb)) on assimilate allocation and crop earliness was eva luated. It was found that the maximum relative tuber growth rate can i nfluence crop earliness more than the other two factors, but when cond itions for tuber growth are optimal, the leaf longevity is most import ant. (C) 1996 Annals of Botany Company