Evaluation of European developed fibre hemp genotypes (Cannabis sativa L.) in semi-arid Mediterranean environment

In the present study two experiments, namely, (i) the adaptation and productivity of different hemp genotypes, both monoecious and dioecious, developed in Central-Northern and Southern Europe, and (ii) the water consumption, water use efficiency (WUE), radiation use efficiency (RUE), leaf transpiration and net photosynthesis of Futura 75 hemp cultivar were studied. Experiments were carried out in Southern Italy in two subsequent year periods. Sowing occurred in May in both years.Results show that fibre hemp, both monoecious and dioecious, performed well giving high productivity; however, fibre hemp needs almost 250. mm of water for monoecious early genotypes and 450. mm for dioecious late genotypes. Higher biomass and stem dry yields were achieved with genotypes developed for Central-Southern environments, such as the dioecious Dioica 88 and Fibranova.In order to estimate the water consumption and WUE of Futura 75, four water regimes (I3, I2, I1 and I0 corresponding respectively to 100%, 50%, 25% ETm restoration and irrigation until crop establishment) were tested.Futura 75 was strongly affected by water shortage and the WUE ranged between 2.73gl-1 in good water conditions and 3.45gl-1 in water stress conditions. The highest light extinction coefficient (k) was observed in water stressed (0.58) than in good watered conditions (0.40). The water stress reduced RUE, LAI and therefore aboveground biomass yield.Air temperature strongly influenced net photosynthesis with an optimum at 24. °C; higher and lower values of air temperature led to a decrease of net photosynthesis