Growth and biomass productivity of kenaf (Hibiscus cannabinus, L.) under different agricultural inputs and management practices in central Greece

The growth and biomass productivity of kenaf (Hibiscus cannabinus, L.) cultivars Tainung 2 and Everglades 41 were determined under three irrigation applications (low: 25%, moderate: 50% and fully: 100% of maximum evapotranspiration; ETm), four nitrogen dressings (0, 50, 100 and 150 kg hat), two sowing dates, and two plant densities (20 and 30 pl m(-2)) in two field experiments carried out on an representative aquic soil of western Thessaly plain (central Greece), in the period 2003-2005. The results demonstrated a paramount effect of sowing time (and thus the availability of the vegetative growing period) on crop growth and biomass productivity; delayed sowings (after mid-May) may reduce biomass production by 38%. Irrigation water had a significant effect (P < 0.05) on growth indices and biomass productivity fluctuating upon flowering from 15.1 to 18.5 and to 20.3 t ha(-1) (3-year average values) for the low, moderate and fully irrigated plants, respectively. Stems are the economic yield comprising about 87% of the total biomass in all cases. The relatively small effect of 50% irrigation to biomass production was attributed to the increased soil moisture status of the studied (aquic) soil. Contrarily, N-fertilization in the studied range did not affect significantly growth and productivity due the high fertility status of the soil, while plant population in the study range had a minor effect (P > 0.05) on biomass accumulation. Cultivars performed similar growth rates (no significant differences), which under full water and nitrogen inputs reached maximum growth rates of 180-220 kg ha(-1) day(-1) which may serve as reference for the assessment of crop performance under production situations at hierarchically lower input and management levels for central Greek conditions. (C) 2010 Elsevier B.V. All rights reserved.