Influence of nitrate and calcium increments on development, growth and early yield in sweet pepper plants

The intensification of transplant production in recent years has led to a wider use of containers, and artificial substrates and greater knowledge of greenhouse conditions. Nevertheless, little work has been reported on the use of nutrient manipulation in vegetable transplant growth control. It is necessary to understand the effect of nutrient level on the ability of the plant to resume growth and produce adequate yield after transplanting. It should be possible to regulate the growth rate of pepper seedling by controlling the concentration of N and Ca in the growing medium. Transplant quality parameters and early yield production of pepper plants may be modified by the composition of nutrient solution both in nursery and in initial greenhouse stages. Levels of NO3- and Ca2+ exceeding normal concentration resulted in decreased seedling growth, shorter internodes, lower shoot/root relations, and higher SLA. These effects are presumably due to the increase in solution salinity and the greater osmotic potential in the growing medium. An adequate balance between growth rates and transplant quality parameters was obtained with 8 meq·L-1. NO3- and 5 meq·L-1 Ca2+ in nursery fertigation solution. When different cultivars of transplanted pepper (Capsicum annuum L) were subjected to very high concentrations of NO3- (32 meq·L-1) and low concentrations of Ca2+ (5 meq·L-1) in nutrient solution, the vegetative growth rate, leaf area expansion parameters and leaf biomass production were positively affected. The effect of these concentrations on reproductive growth stages varied among the different cultivars, but overall the number of early fruit was negatively affected. From a practical standpoint, the nutrient conditioning approach in nursery and osmotic stress in greenhouse may be useful, in conjunction with sanding techniques, to regulate vegetative and reproductive growth patterns of pepper in very warm climatic conditions, such as those in summer in Mediterranean greenhouses.