Enhancement in Bell Pepper (Capsicum annuum L.) Plants with Application of Roholtiella sp. (Nostocales) under Soilless Cultivation

Abstract

Cyanobacteria are found to be renewable and sustainable additives for growth improvement in crops. Extracts and biomass of three nitrogen-fixing cyanobacteria namely, Roholtiella sp. (QUCCCM97), Nostoc ellipsosporum (QUCCCM99), and Desmonostoc danxiaense (QUCCCM112) isolated from Qatar desert environment were tested for their ability to enhance the growth of bell pepper (Capsicum annuum L.) seedlings. Soilless cultivation experiments were carried out by applying the biomass and the aqueous extract of the three cyanobacteria separately. Seedlings were transplanted to Hoagland’s solution under regulated conditions. In total, 2, 4, and 6 mL L−1 of the three microalgae extract as well as 1 and 2 mg L−1 of the three microalgae biomasses (as biofertilizer) were added to the Hoagland solution. An assessment of seedling growth parameters such as shoot length, root length, fresh weight, dry weight, spad index, number of leaves per plant, and growth rate was performed. However, among the different doses and concentrations of investigated QUCCCM97, 99, and 112, our findings revealed that shoot length (cm), root length (cm), fresh weight (g), the number of leaves per plant, and growth rate were positively affected and significantly increased at maximum dose/concentration compared to control plants. With QUCCCM97, shoot length, root length, fresh weight, the number of leaves, and the growth rate increased by 17.5%, 40.3%, 26.0%, 21.6%, and 22.8%, respectively, compared to the control. Additionally, with QUCCCM99, the same parameters increased by 12.3%, 25.3%, 15.1%, 9.3%, 51.8%, respectively. While in presence of QUCCCM112, they increased by 8.7%, 30.1%, 15.6%, 5.4%, 48.6%, respectively. Our results demonstrated that extracts and biomass of cyanobacteria strains investigated here, and particularly Roholtiella sp. (Nostocales), have an enhancement potential of the seedling growth and could be used in modern agriculture to enhance productivity under the soilless system and ensure sustainability.