CEA cultivation strategies for essential mineral elements in Mesembryanthemum crystallinum

Controlled Environment Agriculture (CEA) offers innovative strategies for optimizing crop production and nutritional quality. Specific features of halophytes, such as the ice plant (Mesembryanthemum crystallinum), require diverse cultivation conditions compared to leafy vegetables grown in CEA. This study aimed to assess how light intensity, spectrum, and photoperiod, as well as the pH and salinity of the nutrient solution, affect the growth, macro (P, K, Mg, Ca) and micro (Fe, Mn, Na, Zn) element content, and the elements' distribution in the leaves and roots of the ice plant. Ice plants were grown in walk-in chambers, and five cultivation experiments were performed, comparing the impact of (I) photosynthetically active photon flux densities (PPFDs) of 150, 200, 250, and 300 µmol m^-2 s^-1 over a 16 h photoperiod; (II) the spectral composition of red (R), blue (B), RB, and RBFR (far-red) at 250 µmol m^-2 s^-1 and a 16 h photoperiod; (III) 12 h, 16 h, and 24 h photoperiods at 250 µmol m-2 s-1; (IV) hydroponic solutions of pH 5.0-5.5, 5.5-6.0, and 6.0-6.5, and (V) hydroponic solution salinity concentrations of 0, 50, 100, 150, and 200 mM L^-1 NaCl under optimized lighting conditions. Other cultivation parameters were kept constant in all experiments. The results demonstrate that ice plant biomass productivity is resilient to different lighting and hydroponic cultivation conditions in CEA; however, the lighting conditions significantly affect Mg and Ca contents in plant leaves, while hydroponic nutrient solution pH and salinity have selective effects for different mineral nutrients.