Inoculation with arbuscular mycorrhizal fungi improves seedlings growth of two sahelian date palm cultivars (Phoenix dactylifera L., cv. Nakhla hamra and cv. Tijib) under salinity stresses

This study presents an analysis of the impact of mycorrhizal inoculation on growth under salt stress of date palms cultivars Nakhla hamra (NHH) and Tijib known in the Sahel for their earliness in flowering and fruiting. The seedlings were grown in a greenhouse on a sandy substrate watered to field capacity every two days and were subjected to increasing levels of NaCl (0, 1, 2, 4, 6, 8 and 16 g·L-1) and then inoculated with 5 strains of Glomus (G. aggregatum, G. intraradices, G. verriculosum, G. mosseae, G. fasciculatum). The experimental design was a randomized complete block with three factors (cultivars: Tijib and Nakhla Hamra x seven levels of NaCl concentrations x six levels of inoculum). The results showed that in the absence of NaCl, G. verriculosum significantly enhanced shoot growth: 33.5 cm against 30.3 cm in the control and roots growth: 81.5 cm against 78 cm in NHH, while in Tijib, the growth is stimulated by Glomus fasciculatum: 33.8 cm against 32.7 cm for stems and 90 cm against 86 cm for the roots of inoculated plants and controls. In contrast, in the presence of NaCl 8 g·L-1, NHH has a better growth in the presence of G. intraradices: 37.3 cm against 30.6 cm for stems and 77 cm against 73 for roots, while Tijib grows better in the presence of G. fasciculatum with respectively 31.9 cm against 31.7 cm and 51.27 cm against 51.6 cm for stems and roots of inoculated plants and controls. Biochemical analysis revealed that changes in levels of proline depend on the cultivar, the mycorrhizal strain used and concentrations of NaCl applied. These results open the prospect of using mycorrhizal fungi to improve the productivity of palm trees in the Sahel.