Author(s): M. Sakellarioumakrandonaki; N. G. Danalatos; S. Dassios; A. Chatzinikos
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Keywords: Irrigation; Fiber sorghum; Biomass; Energy crops
Abstract: Growth and biomass yield of the fiber sorghum [Sorghum bicolor (L.) Moench] variety FS-5 were studied under field conditions in central Greece in 2001, using a randomized block design with 3 different irrigation methods (plus non-irrigated control) in four replicates. The irrigation methods were drip irrigation; subsurface irrigation and overhead irrigation with gun sprinkler. All treatments received at regular intervals the same irrigation amount for matching half of the evapotranspiration needs. Overhead irrigation was applied via a gun sprinkler recharging 34 m3/h (operating pressure 4.5 Atm). Drip and subsurface irrigation were applied in rows of 1.6 m apart and 0.6 m between the self-regulated emitters, recharging 3.6 m3/h. The fully automatic subsurface irrigation system was placed at a depth of 0.45 cm from the soil surface. The growth of the crop was measured by means of plant height and leaf area index, which were recorded in periodical samplings throughout the growing period. Biomass production was measured in three harvests during the end of growing period. The results of the first year demonstrated a great superiority of the subsurface irrigation method on total biomass production comparing with the other two methods. The crop irrigated with this system reached a maximum yield of 18 t/ha, rather higher than the yield performed by the drip irrigated plants (12 t/ha), apparently due to the minimal evaporation losses and the better water distribution in the rooting zone occurring under subsurface irrigation. The yield of the crop receiving overhead irrigation did not exceed 10 t/ha due to the substantial water losses through evaporation, deep percolation and nonuniform water application, associated with the use of this system which, however, is currently the most commonly used in central Greece. Maximum yield was attained by late September, before crop maturation, and this should be taken in to consideration for choosing the best harvesting time of the crop. After late September, large negative growth rates were recorded resulting in an appreciable drop in the final dry matter yield.
Year: 2003