Interactive effect of nutrient concentration and container volume on flowering, fruiting, and nutrient uptake of sweet pepper

Flower abortion and low fruit set has long been a problem in sweet pepper (Capsicum annum L.), especially when the flowers are cross-pollinated. Restrictions of nutrient element supply and root volume affect plant vigor and size. To study the interactive effects of nutrient element supply and container volume on pepper flowering and fruiting, a complete interactive experiment (3 x 3) containing three concentrations of nitrogen (N), phosphorus (P), and potassium (K) at a constant ratio and three volumes of containers were conducted using a hydroponic system in a temperature control-greenhouse during a autumn-winter season. The cultivar of sweet pepper was cv. 'Hazera' 1195 and only cross-pollinated flowers were allowed to set fruits. The mean minimum root zone temperature was maintained at 16.3-16.6°C in the middle (18-dm³) and big (33-dm₃) containers at night during the fruit developing stage, it dropped at night to 14.1°C in the small (9-dm³) container. The low concentration nutrient solution containing 3-0.5-1.25 mM of N-P-K, when combined with the small container induced an early flowering and short duration of flowering, that led to early fruit set and maturation. No difference in flowering, fruit set and total fruit yield of pepper was found between middle (6-1-2.5 mM) and high (9-1.5-3.75 mM) nutrient element level when the small and middle containers were used. Plants in the large container significantly delayed the flowering and fruit set when high concentration of nutrient elements was applied, but the total number of fruit set and total plant yield was higher than in the small container. High nutrient element concentration and larger container size produced high fruit yield only when allowed to grow and set fruits for a long period.