Nutrient uptake concentrations of a pepper crop under Mediterranean climate conditions

Knowledge of nutrient to water uptake ratios which are commonly termed "uptake concentrations", are especially important in greenhouse crops when plants are grown in closed-cycle cultivation systems. In such systems, the input ratio between the mass of a nutrient and the volume of water should be equal to the corresponding nutrient to water uptake ratio by the plants, so as to avoid accumulation. Thus, if data about the mean uptake concentrations are known, they can be used to establish nutrient solutions for closed-cycle hydroponic cultivations. Preliminary observations indicated that the nutrient-to-water uptake ratios in crops grown hydroponically in Mediterranean greenhouses may be substantially different than in north-European greenhouses, due to differences in climatic conditions. Furthermore different genotypes or different rootstocks in the case of grafted plants may have an impact on nutrient and water uptake. In the present study, the uptake of water and nutrients was measured in 4 different pepper genotypes ['Orangery', 'Bellisa', 'Sondela', 'Sammy' self-grafted and 'Sammy' grafted onto a commercial rootstock 'RS10' (Capsicum annum L.)]. All plants were grown in a closed NFT system. Mean water uptake ratios (uptake concentrations) of macro- and micronutrients for two time intervals, namely vegetative and 1st reproductive stage, were determined through the estimation of nutrient removal from the recycled nutrient solution. The results of this study indicated that 'Sondela' exhibited the highest uptake concentrations of NO3, Mg nd Ca in comparison with all other treatments In contrast, the uptake concentrations of all nutrients were similar in the grafted and the nongrafted 'Sammy' plants and that must be due to the genotype of the rootstock and the specific combination of the rootstock-scion. © 2017 ISHS