Abstract
Crop growth rate (CGR) response of three warm season C 4 -grasses (cereals) namely: corn ( Zea mays L., cv. Hybrid-5393 VT3), grain sorghum ( Sorghum bicolor L. Moench, cv. Hybrid-84G62 PAT), and foxtail millets ( Setaria italica , cv. German Strain R) grown in pure and mixed stands under low and high water levels was investigated at one month interval namely: 30, 60 and 90 days after emergence (DAE), in pot experiment at Dryland Agriculture Institute, West Texas AM but the CGR was reduced by 42% in the three crops mixed stand than the average of two crops mixed stand at 90 DAE. Corn mixed stand in two crops (average of corn + sorghum and corn + millets) had 78, 75 and 74% higher CGR than the mixed stand of sorghum and millets at 30, 60 and 90 DAE, respectively. Corn and millets mixed stand had 16, 9 and 38% higher CGR than the corn and sorghum mixed stand at 30, 60 and 90 DAE, respectively. Corn had higher CGR under high water at 30 DAE. There was no difference in the CGR of sorghum under low and high water levels at different growth stages. Millets had higher CGR under high water level at 30 DAE, but had lower CGR under high water level at 90 DAE. Among the three crops, corn plants had the higher CGR due to the highest total dry matter accumulation in both shoots and roots and was considered the best competitor in all the mixed stands. Grain sorghum ranked second, while foxtail millets ranked in the bottom in terms of competitiveness in the mixed stands. Keywords: Zea mays , Sorghum bicolor , Setaria italica , competition, water levels, crop growth rate. African Journal of Biotechnology , Vol 13(30) 3036-3051
Highlights
Crop growth rate can be affected by competition among crop plants, because the crops are the members of community and each individual interact with its neighbors (Sadras and Calderini, 2009); and that the competition may have an impact on both above- and below-ground total biomass (Rubio et al, 2001)
German Strain R) was investigated in pure and mixed stands under low water level (50 % less water was applied that required for the high water level) and high water level in pot experiment at Dryland Agriculture Institute, West Texas A&M
The crop growth rate (CGR) declined to 4.5 g m-2 day-1 when corn was grown mixed with sorghum, followed by 4.6 g m-2 day-1 when corn was grown alone in pure stand
Summary
Crop growth rate [the total dry matter accumulation (shoot plus root dry weights) per unit ground area per unit time]. Khan is used to measure the primary productivity of crop plants (Youshida, 1981). Crop growth rate can be affected by competition among crop plants, because the crops are the members of community and each individual interact with its neighbors (Sadras and Calderini, 2009); and that the competition may have an impact on both above- and below-ground total biomass (Rubio et al, 2001). Crop growth requires a limited number of resources, which are light, nutrients and water. Several studies have shown that below-ground competition for water and nutrients can be stronger and can involve more neighbors than aboveground competition for light (Casper and Jackson, 1997).
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