Effect of varying plant population density on aphid infestation level and yield of faba bean

Four plant populations: 8, 16, 24 and 32 plants per square meter were tested for their effects on aphid infestation levels and yield potentiality of faba bean (Vicia faba L.) Giza 843 variety, grown under natural infestation in Sids Agricultural Research Station, Beni-Suef Governorate, throughout two consecutive seasons of 2009/10 and 2010/11. Results indicated that a greater number of cowpea aphids infested the lower dense plant populations. Insect population increased with time in all plant populations tested. Dense planting satisfactorily decreased the proportion of plants infested with cowpea aphid by 27.55 and 34.53 % in 2009/10 and 23.10 and 27.26 % during 2010/11 season at plant population of 24 and 32 plants /m². There has been negative relation between aphid abundance and plant density per unit area observed. Also, there was a positive response of seed yield with higher plant population densities; 24 and 32 plants /m² confirmed in the two successive seasons. The seed yield of faba bean crop cultivated at the rate of 24 and 32 plants /m² increased by (19.02 % and 20.50 %), and (14.66 and 34.02 %), over the two lower plant population densities 8 and 16 plants /m²., in the first and second seasons, respectively. The overall results lead to the conclusion that yields of faba bean Giza 843 variety under environment of infestation with cowpea aphid, A. craccivora in middle Egypt region, could be successfully maximized by planting the crop at 24-32 plants /m² plant density (sowing at 2 seeds /hill in double rows or one seed /hill in three rows, 20 cm hill to hill distance on ridges 60 cm apart).