Here's a study done in roses. They found that spray intervals of 3min on every 15min resulted in roses with improved growth: length and
thickness of flowering stems, length and thickness of flower buds and total leaf
number were enhanced. This was compared to intervals of 3min on every 30min. So in this case more frequent sprayings were better.
EFFECTS OF AMMONIUM RATIO AND
NUTRIENT DELIVERY INTERVAL ON ROSES
GROWING IN AEROPONICS
Authors: A. Jowkar, M. Kafi, M. Babalar, R. Naderi
Keywords:
Rosa L., soilless culture, mist chamber, pressurized air
Abstract:
Roses have been grown for centuries because of their aesthetic value in
landscapes, pots or vases as well as their nutritional and therapeutic
significance. This has led growers to search for means of improving its
production by changing the mode of cultivation and the fertilization regime. The
development of a new aeroponic system is reported here. Stentings of Rosa ×
hybrida Prestige were placed on top of separate mist chambers and nutrient
solutions were sprayed on their bare roots by means of pressurized air.
Aeroponically-grown roses were treated with four NH4
+/total N ratios (0.14,
0.03, 0.02 and 0.00
of a complete nutrient solution and two spray intervals
(3/15 min and 3/30 min on/off). Subsequent growth of plants was measured by
number of flowers, length and thickness of flowering stems, length and
thickness of flower buds, leaf and total dry weight and total leaf number. The
middle range proportions of ammonium-N in the nutrient solutions (0.03 and
0.02) improved the growth characteristics of plants including number of flowers,
leaf and total dry weight, and length and thickness of flower buds. The shorter
spray interval (3/15 min) resulted in roses with improved growth: length and
thickness of flowering stems, length and thickness of flower buds and total leaf
number were enhanced.