Effects of Maize Row Spacing on System Productivity and the Growth of Intercropped Maize in Intercropping System

The change for row spacing of intercropped maize directly affects production of intercropping system, therefore, it is necessary for high yield of intercropping system to match reasonable row spacing. Two field experiments (a experiment was conducted at Wuwei in 2010 and another at Zhangye in 2014 in Gansu Province) were carried out to determine the effect of row spacing of intercropped maize on intercropping system production and growth of intercropped maize in two intercropping systems (wheat/maize and faba bean/maize). The experiments included 5 maize row spacing treatments (D0:0 cm, D20:20 cm, D40:40 cm, D60:60 cm, D80:80 cm),the yield, agronomy traits and growth of intercropped maize were investigated. The results showed that there were no significant effects of row spacing of intercropped maize on yield of intercropped companion crops, row spacing change mainly affected the yield of intercropped maize; the yield of intercropped maize, the total yield of intercropping system and SP (system productivity) under D60 in 2010 and D40 in 2014 were the greatest in both intercropping systems. With increasing of row spacing of intercropped maize, SP increased firstly, and then decreased, a inflection appeared at D60. The ear grain number, the 100-grains weight and grain weight per plant were significantly affected by different row spacing treatments, the peak value was 132 g·plant^-1 (D60) in 2010 and 216 g·plant^-1 (D40) in 2014 in wheat/maize intercropping system, and 158 g·plant^-1 (D40) in 2010 and 220 g·plant^-1 (D40) in 2014 in faba bean/maize intercropping system. The growth rate of intercropped maize during co-growth period was significant lower than those during single growth period, the growth rate under D40 and D60 was always greater than other treatments in any sampling period. Therefore, the reasonable row spacing of intercropped maize was 40 cm and 60 cm in wheat/maize and faba bean/maize intercropping in Hexi corridor, the system production was the greatest