A field study of the relationship between pre‐planting density of Globodera pallida and the growth and yield of two potato cultivars of differing tolerance

Abstract

Non-resistant but tolerant cv. Cara and non-resistant but relatively intolerant cv. Pentland Dell were grown in split plots encompassing a range of population densities of potato cyst nematode, Globodera pallida. Light interception and its efficiency of conversion were estimated by regular ground cover measurements and plant harvests. It was concluded that increasing levels of infestation with G. pallida only slightly decreased the efficiency of utilisation of intercepted radiation. Heavy infestation of G . pallida initially decreased the top growth and light interception of both cultivars by similar proportions, but in later harvests, this adverse effect markedly decreased for Cara whereas it slightly increased for Pentland Dell. This difference was due to the heavily infested Cara eventually achieving and maintaining 100% ground cover whereas the equivalent Pentland Dell never exceeded 75% ground cover. Consequently, final tuber yields were decreased much more for Pentland Dell than for Cara though the decreases in tuber yield were less than those for top growth. The importance of nematode effects on top growth, and hence on light interception, with regard t o both yield losses and tolerance differences, were clearly demonstrated. Both linear and logarithmic models were used to describe the relationship between the initial population density of G. pallida and yield, and the implications of differences in tolerance on the parameters in the logarithmic model are discussed.

The influence of drought and cyst nematodes on potato growth. 4. Effects on crop growth under field conditions of four cultivars differing in tolerance

“…This largely reinforces the hypothesis of Wallace (1987) that selection for drought tolerance may yield genotypes which are tolerant for potato cyst nematodes and vice versa. Trudgill et al (1990) suggested that late cultivars which intercept the highest amount of intercepted radiation in the absence of nematodes will also show the highest degree of tolerance. This is partly confirmed by the data presented in this paper: 'Elles' intercepted the highest amount of solar radiation in fumigated and irrigated conditions in each year (Table 2) and it also proved to be the most tolerant.…”

Analyses of the effects of potato cyst nematodes (Globodera pallida) on growth, physiology and yield of potato cultivars in field plots at three levels of soil compaction

“…Yield loss is often associated with reduced light interception by the crop due to reduced crop leaf area (Trudgill, Marshall & Phillips, 1990;Haverkort, Boerma, Velema & Van de Waart, 1992). Whether infection by nematodes reduces leaf area by decreasing leaf growth, accelerating leaf senescence, lowering the specific leaf area, or by a combination of these mechanisms, is unclear.…”

Field trials using single potato plants as whole plots, with and without nematicide treatment, to assess tolerance of attack by Globodera rostochiensis

“…The relationship between yield and nematode density is described by the equation of Seinhorst (1986). This equation was used by Trudgill, Marshall & Phillips (1990) to compute values of T(the nematode population density below which plant damage is negligible) at 0.91 and 3.27 eggs/g soil and values of tn (minimum yield expressed in proportional terms) at 0.00 and 0.74 for Pentland Dell and Cara respectively. The slope of the curve relating yield 63 1990 Association of Applied Biologists to nematode density is much steeper for Pentland Dell than Cara and this is due to its relative intolerance of nematode attack.…”