An experiment was conducted to determine optimum fertigation duration for cucumber grown using aquaculture effluent (AE) from Nile tilapia, with and without nutrient supplementation compared to conventional hydroponic (cHP) nutrient solution. A split plot design nested in a randomized complete block with four replications was used . Main-plot factor was f ertigation duration ( 1, 2, 3, or 4 minutes) and subplot factor was nutrient solution type (cHP, supplemented AE , or non-supplemented AE ). Fertigation was supplied every 30 during daylight hours . Analysis of variance showed that, plants grown in cHP solution had significantly (p=0.0343) lower (19.55 µ mol [CO2] m -2 s-1) leaf photosynthetic capacity (Amax ) than both supplemented and non-supplemented AE (21.13 and 20.78 µmol [CO2] m-2 s-1 respectively) . The effect of fertigation duration on Amax also depended on nutrient solution type (interaction effect; p=0.0342) . Stomatal conductance decreased with increasing fertigation duration, significantly lowering at 4 minutes ( 432.9 mmol [H2O] m-2 s-1) . The chlorophyll index ( SPAD value) measured at 28 days after transplanting showed significant ly (p=0.0339) lower value for non-supplemented AE (34.84 ) than cHP (36.45 ) and supplemented AE ( 36.02) but was not affected by fertigation duration or its interaction with nutrient solution type. There was no significant (p>0.05) effect of the factors or their interaction on yield recorded so far . By adjusting fertigation duration and achieving significantly similar yields imply reducing fertigation duration could increase water and nutrient use efficiency. Also, the comparative yield performance of non-supplemented TE with cHP and supplemented TE shows promising potential in using tilapia effluent for soilless cucumber production.
Keywords : aquaponics, nutrient use efficiency, cucumber fertigation , timer clock