Biological Engineering and Its Relationship to Nematode Resistance

The management of plant parasitic nematodes and related crop techniques applied in Egypt are reviewed. Methods used to manage soil nematodes include growing leguminous plants with cereals to exploit crop interference, through plant competition for above and belowground resources. Intercropping aims at increasing agricultural productivity, maximizing land usage with fewer inputs. Using available agricultural resources, this biological engineering approach represents a promising solution for nematode management. The crop planting geometry must be assessed to understand its influence on intercrops and the impact on the biological engineering plan. The optimum spatial arrangement of intercrops is the basis to define a suitable crop planting geometry. Different forms of biological engineering treatments can affect resistance/tolerance towards soil nematodes. They may consider crop species that interfere strongly with each other, particularly when water, temperature, and mineral nutrients are limiting. In this chapter, we discuss the role and influence of crop geometry on plant parasitic nematodes in a soybean-corn mix cropping patterns. Experimental field data showed that the nematode counts were higher in soybean alone than in the intercropped soybeans, during two repeated seasons. Soybean cv Crawford showed total nematode counts higher than those of cvs Giza 22 and Giza 35. When the latter cvs were grown in a mixed system, they recorded higher land equivalent ratio (LER) values and lower nematode counts than in other treatments, during two seasons. Soybean cv Giza 111 consistently outperformed the other treatments regarding LER and reduced nematode counts, at the highest density of intercropped plants. The overall numbers of nematodes in the soybean rhizosphere and the yield of soybean seeds were greatly impacted by the interaction between cropping systems and the densities of plants.