Growth and yield of rose in a closed soilless system on two inert substrates
2003
Paradiso, R. | Raimondi, G. | De Pascale, S.
The experiment was carried out in Naples (40° 51’ N) during an 18-month period, beginning in January 1999, in a heated greenhouse. Water consumption, plant growth and cut flowers production were investigated on rose plants (CV Red France) grown on pumice and lapillus in a closed-loop system, in which the fertigation volume was adjusted to hydraulic properties of the substrates. The substrates differed in particle size distribution, which was higher in pumice than in lapillus (51.5 vs. 35.5% in weight of particles greater than 8 mm). The amount of Easily Available Water (EAW), in the suction range from 10 and to 50 cm, was 1.9% in volume in pumice and 2.5% in lapillus. Plants were grown in plastic channels and nutrient solution was supplied via a drip-system. Fertigation frequency was based on the crop transpiration rate: watering pulse started when ETp reached the threshold value of 0.55 mm and 1.4 mm was applied (equal to the mean value of the EAWs of the substrates). From September 1999 to August 2000, the number of irrigation pulses ranged from 3 to 8 per day and 193 L of fresh nutrient solution per plant were applied. Total water consumption was unaffected by growing media, reaching the mean level of 173 L plant-1. The recirculating nutrient solution lasted 50 days on average and, at the end of the year, the total volume of waste water discharged out of the system was approximately 10% of the supplied solution. The substrates did not affect significantly plant growth and cut flower yield and quality, with 23 flowers produced per plant and good qualitative standards.
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