Tolerance of potato to potato cyst nematodes (Globodera rostochiensis and G. pallida) in relation to the growth and efficiency of the root system

Potato cyst-nematode (Globodera rostochiensis) was shown to damage potato plants in several ways. A major cause of damage, affecting all cultivars to a similar extent, was a reduction in the top to root weight ratio. Intolerant cultivars also suffered a reduction in the weight and length of their root systems when grown in heavily infested soil, the combined damage resulting in a marked decrease in nutrient uptake and top growth. In addition intolerant cultivars tended to senesce prematurely when heavily infested, further decreasing their leaf area duration and yield. Cultivars tolerant of potato cyst-nematode (PCN) differed from intolerant cultivars in that their root systems tended to grow larger in heavily infested soil than in lightly infested or nematicide-treated soil, so partly compensating for the reduction in the top/root ratio. In a growth cabinet experiment Maris Anchor was more severely damaged at a soil temperature of 10 than at 15 °C. In a glasshouse, without temperature control, differences were obtained between cultivars in small pots (10 cm) in the effect of PCN on root growth which correlated well with differences in tolerance obtained in field trials.