FOLIAR CALCIUM-CONCENTRATION OF POTATO AND ITS RELATION TO GENOTYPE LATENESS AND TOLERANCE OF CYST NEMATODES

In field trials during three years respectively 18, 22 and 57 potato g enotypes were grown on soils moderately or heavily infested with potat o cyst nematodes (Globodera pallida) after soils were fumigated or not . Nematode infection increased leaf calcium contents but genotypes tha t were relatively tolerant of potato cyst nematodes (Globodera pallida ) had lower leaf calcium concentrations on a particular sampling date. Tolerance of potato cyst nematodes was closely linked to genotype lat eness and may be related to tolerance of drought. When using the metho d in plant breeding and screening for genotypes with tolerance, plants may be planted in infected or in uninfected soils, without influencin g the outcome. The relationship between tolerance and calcium contents was dearest when sampling took place towards the end of the growing s eason when the variability was at it highest with a good distinction b etween newly formed leaves in late maturing genotypes and aged leaves in early maturing cultivars.