Closed-loop soilless cultivation system of Curcuma alismatifolia under moderate saline stress

Closed or virtually­closed (no­drain) growing systems, where water is recovered and reused, can maximize resources use efficiency and minimize the runoff­related environmental pollution in protected floriculture. Nevertheless these systems have high investment and running costs and must rely on high quality water, which is not always available in Mediterranean coastal regions. With the aim of contributing to the improvement of hydroponic cut flower cultivation in Southern Italy, experiments were carried out on two cultivars of Curcuma alismatifolia Gagnep (‘Pink’and 'White') to verify the response of this species to a closed growing systems. In addition, the effects of increasing the salinity of the recirculating nutrient solution (0%; 0.125% and 0.25% NaCl) were investigated on the cultivar ‘Pink’. During the experiment plant growth, number of cut flower per plant, gas exchange, water relations and leaf mineral concentration were measured. The results demonstrated that nutrients and water use efficiencies can be considerably improved upon introduction of closed soilless systems. These systems are suitable for cultivation of crops with short growing cycle such as Curcuma and other bulbous crops also in presence of moderately saline water. Indeed, since to an increasing water salinity corresponded decreasing leaf area end total plant biomass, the water uptakes were reduced. There was also a clear effect of salinity on cut flower yield and mineral composition of leaves and rhizomes that suggested to adjust the fertilizer concentration to the growth phases of the plant.