Effects of Different Nutrient Formulations Supplied at Different Crop Growth Stages on Yield in Bell Pepper (Capsicum annuum L.) Plants Grown in Stonewool

Effects of fertigation with different pre-mixed fertilizers on growth, yield, leaf chlorophyll content and photosynthesis of bell pepper (Capsicum annuum L.) cultivar 'California Wonder' plants grown hydroponically in stonewool were investigated. Three different pre-mixed fertilizer formulations (Scotts Peters Professional water soluble fertilizer) were used: 20-20-20; 20-10-20; and 21-07-21 to provide NPK concentrations of (F1) 126-55-106; (F2) 256-55-214; and (F3) 385-55-321 mg/L respectively. P concentration (55 mg/L) and the ratio of N:K concentrations (1.2:1.0) were kept constant whilst N and K concentration trebled from F1 to F3. Fertigation regimes were applied according to plant physiological stage: (S1) vegetative stage, (S2) flowering stage, and (S3) fruiting stage. The experiment comprised of seven treatments replicated three times in a completely randomised design. Water and fertilizer solution was supplied automatically to the roots with five irrigation schedules per day (8:00; 10:00; 12:00; 14:00 and 16:00 h) and given similar volumes of nutrient solutions per irrigation event in each stage (6 min (S1), 8 min (S2) and 10 min (S3) daily. This study showed that fertigation with N and K gradually increasing from 126-106 to 265-214 and finally 385-321 mg/L (treatment 1) increased fruit yield of bell pepper significantly by 8% over the control. Higher yield in treatment 1 was associated with the higher leaf area, total dry matter production, number of fruits per plant and higher fertilizer-use efficiency.