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

Abstract

In field experiments carried out in 3 years with and without fumigation and irrigation 4 cultivars of potato differed in their tolerance of cyst nematodes (Globoderapallida). Ground cover, tuber and foliage fresh and dry yields were determined at regular intervals. From these measurements, intercepted radiation, radiation use efficiency for production of total and tuber dry matter and the apparent amount of intercepted radiation at tuber initiation were calculated and compared for all the treatments. The results indicate that cultivars which best maintained ground cover in the absence of nematodes also maintain it best in the presence of nematodes. Such cultivars gave the highest yields at all levels of nematode infestation because the radiation use efficiencies were far less affected by nematodes than was intercepted radiation. The similarity of the responses to nematode infection and to drought and the absence of interaction between these two stress factors facilitated crop simulation modelling. Th e relationships found here may well be wider used, though they will have to be validated for other cultivars and growing conditions.

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.…”

Relationship between potato cyst nematodes and their principal host. I. A literature review

“…In the case of nematode attack, there is little or no compensation, which consequently leads to poor foliar development and also tends to lead to premature senescence of the crop. This further decreases leaf area duration and yield (Trudgill & Cotes, 1983: Haverkort et al, 1992.…”

“…All these effects lead to a considerably reduced ground cover duration (Haydock, 1989: Haverkort et al, 1992. Plant development is delayed and the formation of tubers and flowering of infected plants is later than that of uninfected plants.…”

Using systems approaches to design and evaluate ideotypes for specific environments

“…The new rice crop type design, mentioned earlier in this paper, has a reduced tillering capacity to reduce the contribution of non productive tillers to increase yield potential. In view of designing crop ideosystems that meet objectives at the eco-regionallevel as stated in the introduction, it is essential to quantify the trade offs between the reduction of non productive tillers and g m -2 ), the amount of photosynthetically active solar radiation intercepted (~, J m -2 ), the conversion efficiency into dry matter (E, g J-1 ), and the proportion of total dry matter in the harvested parts (H,,-) and its dry matter content (Dmc) (Haverkort et al 1992 the compensation capacity to minimize pest damage after early leaf removal. Integrated experimental and modelling studies can help reveal these trade offs.…”

“…The effect of nematodes on potatoes was studied in detail by Haverkort et al ( 1991Haverkort et al ( , 1992. Figure 4 demonstrates the strong impact of nematodes and water stress on leaf area development (measured as infrared reflectance), resulting in a strong reduction of~.…”