Abstract

The present investigation was conducted at Giza Agricultural Experiments and Research Station, Agricultural Research Center (ARC), Egypt during the two successive seasons 2016 and 2017 to evaluate water consumption and insect infestation of three soybean cultivars under different intercropping systems with maize to increase land usage and economic return. Nine treatments were the combinations between three intercropping systems (alternating ridges “2 maize: 2 soybean and 2 maize: 4 soybean”and mixed intercropping systems) and three soybean cultivars (Giza 22, Giza 35 and Crawford) in addition to sole plantings of both the crops. A split plot distribution in randomized complete block design with three replicates was used. Intercropping systems were randomly assigned to the main plots and soybean cultivars were allocated in sub-plots. Growing soybean cultivar Giza 22 with maize gave higher water consumptive use (WCU) in mixed intercropping system than the others. Conversely, intercropping soybean cultivar Crawford with maize had the lowest WCU in alternating ridges 2: 4. Lower aphids infestation was observed on leaves of soybean cultivar Giza 22 in mixed intercropping system than the others. Lower whitefly infestation was recorded on leaves of cultivar Giza 35 in alternating ridges 2: 4 than the others. Lower leaf miner fly infestation was obtained on soybean cultivar Giza 22 leaves in alternating ridges 2: 4 than the others. Lower thrips infestation was obtained on leaves of soybean cultivar Giza 35 in alternating ridges 2: 2 than the others. Mixed system had the highest most maize traits. Maize grain yield and its attributes were not affected by soybean cultivars or the interaction. Alternating ridges 2: 4 had higher all soybean parameters than the others. Soybean cultivar Giza 22 had higher plant height, seed yields per plant and per ha, as well as harvest index than the other soybean cultivars. Growing cultivar Giza 22 in alternating ridges 2: 4 had higher seed yields per plant and per ha than others. Higher land equivalent ratio (LER) and economic return were achieved by growing soybean Giza 22 with maize in mixed system than those of maize sole planting. Growing two rows of soybean cultivar Giza 22 in middle of maize beds achieved 1.11 and 1.21 ton of soybean seeds/ha and 8.38 and 8.94 ton of maize grains/ha in the first and second seasons, respectively. This treatment had the highest WCU (893 and 897 mm), LER (1.26 and 1.26) and net return (USD 1234 and 1391/ha), as well as the lowest number of aphids per soybean leaf (4.2 and 5.2) in the first and second seasons, respectively, compared with the other treatments.