Abstract

The present investigation was carried out 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 soybean mosaic virus (SMV) infection of intercropped three soybean cultivars with maize under different soybean plant densities to increase land usage and economic return. The experiment included nine treatments which were the combinations of three soybean plant densities (two rows, three rows and four rows per ridge were expressed as 50, 75 and 100% of sole soybean plant density) and three soybean cultivars (Giza 21, Giza 82 and Giza 111) under intercropping system, as well as sole plantings of both the crops. A split plot distribution in randomized complete block design with three replicates was used. Soybean plant densities were randomly assigned to the main plots and soybean cultivars were allocated in sub-plots. With respect to WCU, increasing soybean plant density of soybean cultivar Giza 111 from 50 to 100% of sole planting increased WCU of the intercrops (100% maize + 100% soybean cultivar Giza 111). Conversely, decreasing soybean plant density of soybean cultivar Giza 21 from 100 to 50% of sole planting decreased WCU of the intercrops (100% maize + 50% soybean cultivar Giza 21). With regard to SMV infection and transmission, leaves of soybean cultivars Giza 21 and Giza 111 had lower SMV infection and transmission by increasing soybean plant density from 50 to 100% of sole planting under intercropping system than the other treatments in both the seasons. Leaf storage proteins revealed variations among the tested soybean cultivars under different soybean plant densities in intercropping system. Soybean cultivar Giza 21 had presence of six protein bands (35, 75, 100, 135, 180 and 245 kDa) by increasing soybean plant density from 50 to 100% of sole planting under intercropping system. Meanwhile, soybean cultivar Giza 82 was susceptible cultivar to SMV infection and transmission by increasing soybean plant density from 50 to 100% of sole planting under intercropping system. Soybean cultivar Giza 111 had one protein band was newly formed by increasing soybean plant density from 50 to 100% of sole planting under intercropping system. With respect to maize crop, All the studied maize traits were not affected significantly by soybean plant densities, soybean cultivars or the interaction. With respect to soybean crop, Most of the studied soybean parameters were significantly affected by soybean plant densities in both the seasons. Soybean cultivar Giza 111 had lower light intensity at middle and bottom of the plant than the others in both the seasons. Increasing soybean plant density of cultivar Giza 111 from 50 to 100% of sole planting had lower light intensity at middle of plant and higher seed yield per ha than the others under intercropping system in both the seasons. With regard to land equivalent ratio (LER) and economic return, the highest LER and economic return were achieved by increasing soybean plant density of cultivar Giza 111 from 50% to 100%.