The writer draws attention to some factors influencing the breeding of agricultural crops in the Netherlands . The mutual influence of breeding new varieties, research on varieties, seed production, agricultural production and export is explained .
In the Netherlands, farmers on average purchase approved seed potatoes once in three years, which equals the frequency of replacement of the seed of rye . On the area covered by wheat five-eighths is sown with approved seed and of peas and oats, onehalf. In the case of sugar beet, fodder beet and some other crops (including vegetables) 100 % original seed is used .
The writer draws attention in particular to the reasons why there is a continuous need for new seed and seed potatoes . As causes are mentioned : 1 . the fact that a farmer did not grow a particular crop in the previous year ; 2 . that he had difficulties with the seed production of a given variety or the variety deteriorated owing to impurity, diseases or admixtures ; 3 . the wish to choose a new variety of better yielding capacity or other favourable properties ; 4 . purchase of original seed of a variety in demand for increase to once grown original seed or purchase of first rate starting material from the clonal selection farms for growing seed potatoes of a variety in demand .