Potential And Water-Limited Growth And Productivity Of Fiber Sorghum In Central Greece Irrigated By Surface And Subsurface Drip Methods On A Rainy And A Dry Year

Growth evolution and biomass yield of fiber sorghum [Sorghum bicolor (L.) Moench] variety FS-5 were studied under field conditions in central Greece in the years 2001 and 2002, using a completely randomized block design with three treatments in four replicates.(including control) The project comprised two irrigation methods: conventional drip irrigation and modern subsurface drip irrigation. Both treatments received at regular intervals the same irrigation amount for matching half of the evapotranspiration needs (supplemental irrigation) in the first year (2001), and the total evapotranspiration needs (full irrigation) in the second year (2002). Irrigation in both systems was applied in laterals placed 1.6 m apart with a distance of 0.6 m between the self-regulated emitters, recharging 3.75 m3 h-1. The fully automatic subsurface irrigation system was placed at a depth of 0.45 cm from the soil surface. The growth (plant height, leaf area index) and biomass productivity of the crop was measured in periodical samplings throughout the growing period in both years. The results demonstrated a great superiority of the subsurface drip method on growth and total biomass production apparently due to the minimal evaporation losses and the better water distribution in the rooting zone occurring under subsurface irrigation. The crop irrigated with this system reached yields of 38.6 and 18 t ha-1, under full (in 2002) and supplemental (in 2001) irrigation, respectively. The respective yields under surface drip irrigation were significantly lower, i.e. 33.3 t ha–1 (in 2002) and 12 t ha–1 (in 2001). Moreover, the obtained results demonstrated the great potentiality of fiber sorghum as alternative commodity for biomass production in Greece, according to the focus of the sustainable, alternative agriculture under both high and low irrigation inputs. Key-words: fiber sorghum, biomass production, bio-energy crops, modern irrigation, water conservation