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 hempgenotypes, 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 andnet photosynthesis of Futura 75 hemp cultivar were studied. Experiments were carried out in SouthernItaly 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 fordioecious late genotypes. Higher biomass and stem dry yields were achieved with genotypes developedfor 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, I1and I0corresponding 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 2.73 g l-1in goodwater conditions and 3.45 g l-1in water stress conditions. The highest light extinction coefficient (k) wasobserved 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 24oC; higher and lowervalues of air temperature led to a decrease of net photosynthesis.