Algae-based biofertilizer for date palm cultivation in Qatar

Abstract

Date palm (Phoenix dactylifera L.) is the main fruit crop found in the arid and semi-arid regions of the world. It naturally adapts to the adverse environments of extreme heat and water scarcity and prevents further desertification in addition to producing fruits with high nutritional value. It is seen in many parts of the world that traditional cultivation practices such as mixed planting and chemical fertilizers have led to low fruit quality resulting in low market values. Long generation time also hinders production of the dates. Tissue culture is therefore considered the most promising solution for rapid large-scale production of true-to-type clonal plants. The plantlets originating from in vitro callus proliferation are transferred from synthetic media to soil. The conventional method of using chemical fertilizers also leads to low plantlet viability with increased environmental and health risk. The current research targets the use of a local microalga, Tetraselmis sp. QUCCCM8, identified as an organic source of nutrients, a substitute for chemical fertilizers to acclimatize cultured date palmlets to soil. Soil was supplemented with different concentrations of algal biomass and plant growth was monitored for 3 months. Soil without any fertilizer and soil amended with 1 g conventional fertilizer were used as negative and positive control, respectively. Supplementation with 0.5 g of algal biomass led to higher plant growth rates, 100% survival rates, high ability of rooting (3.17 ± 0.14 roots), higher number of leaves (2.5 ± 0.25 leaves), largest stem thickness, longer shoot (33.75 ± 1.56 cm), and higher total chlorophyll (159.61 ± 9.6 mg L⁻¹) as compared to conventional fertilizer. These stated findings are significantly higher than the control. Furthermore, elemental analysis of the soil showed that supplementation with algal biomass increased the soil total nitrogen, potassium, and phosphorus contents essential for plant growth. Finally, the comparison of heavy metals composition between soils amended with conventional fertilizer and algae-based fertilizer highlights the potential use of algae as a safe and efficient biofertilizer post tissue culture mode of plantlet generation. This enhanced the viability of healthy plantlets without affecting the environment, averting usage of chemical fertilizers