Crop physiological responses to infection by potato cyst nematode (Globodera spp.)

Abstract

Fresh potato tuber yields are determined by the total amount of photosynthetically active radiation intercepted by the green foliage of the crop, its conversion efficiency into dry matter, the proportion of dry matter allocated to the tubers and the tuber dry matter concentration. Reduced light interception at the beginning and at the end of the growing season, best explain yield losses following infection by potato cyst nematode (Globodera spp.). Retarded canopy closure during canopy establishment is due to a reduced photosynthetic rate (caused by reduced nutrient uptake rates, hormonal signalling and disrupted plant water relations), increased dry matter allocation to the roots, the formation of fewer stems and the leaves being smaller and thicker. In the second half of the growing season crops infected by potato cyst nematode senesce earlier because the reduced assimilation rate leads to reduced formation of new leaves and the reduced water and nutrient uptake is aggravated because rooting depth is less whereas water and nutrients are depleted in the rooted zone leading to increased leaf shedding. Moreover, tuber fresh yields are reduced because infection by potato cyst nematode reduces the number of tubers and increases the tuber dry matter concentration.

The short-term and long-term effects of potato cyst nematode infection on crop functioning are illustrated and their implications for plant breeding for tolerance, cultural practices and modelling are discussed.