Epsilon Archive for Student Projects

Abstract

Sweet basil of the variety Genovese Gigante is an economically important crop with common use in the gastronomic, medical and cosmetic fields, to name a few, due to the high content of essential oils (EO). Indoor cultivation is a viable alternative to grow sweet basil all-year-round, independent of the outdoor conditions. There is a need to optimize the cultivation conditions for indoor growth in terms of both high productivity and optimal EO content. The study aimed to explore various light and nutrient regimes in order to assess their effects on morphology, growth rate (RG), EO composition and nutrient uptake of basil grown in a hydroponic system.

Light emitting diode (LED) lights of blue and red were used and to generate various light treatment coloured cellophane are added. The light settings green, yellow and control (no added cellophane) were used. The light settings were combined with two nutrient regimes of the commercial fertilizers ‘Blomstra’ and ‘Hydro A+B’ by Gold Label. After two months of growth the sweet basil was assessed in terms of (a) the morphological and physiological traits plant biomass, height, leaf length and chlorophyll content (SPAD) as well as (b) the contents of EO and (c) the nutrient elements N, P, K, Ca, Na, Mg and S.

The results showed a significant increase in biomass, height, leaf size and SPAD as did nutrient uptake (N, P, K, Ca, Mg, Na, S) and the EO eucalyptol, linalool and eugenol with increasing PAR (green<yellow<control). The results showed no support for greater enrichment of EO in plants undergoing the light treatments of green and yellow light.

Nutrient ratios closest to the recommended concentrations for herbaceous plants were found in ‘Blomstra’ nutrient solution. N:P-ratio in the plants and biomass was negatively correlated for plants grown with ‘Blomstra’, indicating a more optimal concentration of nutrient supply. Lower biomass was found in the plants grown with ‘Hydro A+B’. The higher nutrient levels in ‘Hydro A+B’ could have worked toxic on the sweet basil and limited its growth. A possible trade-off effect was found optimizing for RG and EO concentrations using the fertilizer ‘Hydro A+B’, concluding that the combination of nutrient elements influences the correlation between biomass and EO. This discovery can practically be implemented in the farming system.

The combination of ‘Blomstra’ fertilizer and control LED-light treatment had over all positive effects on the studied traits of biomass, morphology and physiological traits, nutrient uptake and EO composition. The EO estragole, with antimicrobial properties, was found in high concentrations in a contaminated farming system. Estragole levels could be practically enforced as indicators of pollutants in the cultivation environment when growing sweet basil.