EFFECTS OF ENVIRONMENTAL AND AGRONOMIC FACTORS ON KENAF (HIBISCUS CANNABINUS L.) IN PO VALLEY

ABSTRACT: Kenaf (Hibiscus cannabinus L.) is a fibre crop that can be used as a biomass crop. Results of trials conducted in the 90’s years by University of Bologna in several places of the Po Valley have shown useful indications about the effects of environmental and agronomic factors on yield and duration of the crop cycle. The year effect seemed to be very important on the life cycle duration, from 85 to 160 days between the sowing and the harvest time. The fresh stem yield ranged from 20 to 80 t ha-1, seemingly related to the amount of rainfall. The optimal harvest time seemed to be in the end of September for most of genotypes, whereas long cycle varieties harvested twenty days later have increased production. Trials testing several genotypes without water supply have shown that long cycle cultivars were more productive with a field variation from 11.5 to 16.5 t ha-1 of dry matter. In Northern Italy climatic conditions only rescue irrigation seemed to be necessary during dry years. The restoration of 50 % of ETM increased the dry biomass yield of 15-25%, but irrigation did not seemed to be economically convenient. The density trials have shown that the limit of 100-120 plants m-2 as the optimal for biomass production