Effects of Fertilization, Arbuscular Mycorrhiza, and Salinity on Growth, Yield, and Bioactive Compounds of Two Aloe Species

Three greenhouse experiments were carried out to compare the responses of Aloe arborescens and Aloe barbadensis with organic fertilization (standard or reduced fertilization level), arbuscular mycorrhiza [with AM(+AM) or without AM (–AM)], and salinity (1 or 80mM NaCl) in terms of plant growth, leaf yield, mineral composition, and nutraceutical value. In all experiments, the yield of fresh leaves was significantly higher by 320%, 252%, and 72%, respectively, in A. barbadensis in comparison with A. arborescens. Doubling the fertilizer dose, plant growth parameters increased, but the bioactive compounds were negatively affected. The highest antioxidant activity was recorded with A. barbadensis using both fertilization regimes, whereas the highest values of anthraquinones aloin were observed in A. barbadensis using a reduced fertilization regime and when plants were inoculated with AM fungi. b-polysaccharide concentration was significantly higher in A. barbadensis in comparison with A. arborescens and was increased by 33%when plants were inoculated with AM fungi. In both Aloe species, increasing the salinity decreased the leaf freshweight and total dry biomass but increased the aloin and b-polysaccharides content by 66% and 21%, respectively. The results suggest that cultural practices such as organic fertilization, inoculation with AM fungi, and irrigation with saline water can represent effective tools to achieve a more favorable phytochemical profile.