TWO EXPERIMENTS were conducted during the growing summer seasons 2008-2009 at Shandaweel Agric. Res. St., (Upper Egypt) to study the effect of intercropping maize with sorghum, soybean and cowpea on yield and yield components. There were three intercropping crops: A1 (maize + sorghum), A2 (maize+ soybean) and A3 (maize + cowpea) in three intercropping patterns P1, P2 and P3 (2:2, 2:4 and 4:4), respectively. The experiments were established as split plots intercropped in randomized complete block design (RCBD) with three replications. The results show significantly higher values of yield and yield
components were recorded by the maize + soybean intercrop followed by the maize + cowpea intercrop in both seasons. The yield and yield components of intercropped crops (sorghum, soybean and cowpea) were decreased as compared
with solid. The reduction in yield and yield components of this crops due to the shading of maize plants, that results in decrease interception of solar radiation from top of maize crop to top of intercropped crops (soybean and cowpea). The reductions in light intensity of the treatments maize + soybean and maize + cowpea intercrops were 39 and 38% in the combined of the two
seasons as compared with solid planting. The highest of yield and yield components were recorded by 2:4 pattern (P2) compared with the other patterns (2:2 and 4:4) due to light interception that was greater in 2:4. The reduction in yield were 51,44 and 52% for maize 61,43 and 59% for sorghum, 60,33 and 60% for soybean and 53.33 and 58% for cowpea in 2:2, 2:4 and 4:4
patterns compared with solid in both seasons, respectively. The total land equivalent ratio (LER) value was (1.22) when intercropped with soybean or cowpea. A similar trend to that of the LER was observed for relative crowding coefficient (Rcc), aggressivity (Agg) and competition ratio (CR). The highest values of monetary advantage index (MAI) (1044.46) were observed when intercropping with soybean at 4:4 pattern, while the lowest value was observed in maize + sorghum intercrop at 2:4 pattern. The data of aggressivity showed that maize was the dominant (Ag positive) and the intercropped crops were
dominated (Ag negative).