THE EFFECT OF ARBUSCULAR MYCORRHIZE (AM) FUNGI ON THE ESTABLISHMENT OF DATE PALM (PHOENIX DACTYLIFERA L.) UNDER SALINE CONDITIONS IN THE UAE

The date palm (Phoenix dactylifera L.) has great socio-economic importance in the UAE and the Arabian Peninsula. Research at the International Centre for Biosaline Agriculture (ICBA) has shown that date palms are obligatory dependent on arbuscular mycorrhiza (AM) fungi for growth under saline field conditions. One-year-old in vitro seedlings of the date palm variety ‘Khenizi’ were inoculated with commercial AM inoculum, BioMyc^Vital in a pot trial conducted at the ICBA plastic house. Plants were irrigated with fresh water as control and 5 and 15 dS m^-1 salinity levels. Two fertilizer levels, full fertilizer level (15, 30 and 5 g/month/plant of NPK (20:20:20), compost mix and Osmocote (12:13:13+TE), respectively) and low fertilizer level which was 1/3 of the full fertilizer level were used as fertility treatments. The results showed significant differences among treatment means. However, no interaction among treatment factors was found. The mycorrhizal inoculum stimulated growth of date palm under all salinity conditions. Within 6 months, plant height and trunk diameter of plants inoculated with BioMyc^Vital was increased by 60.7 and 28.8% respectively, with fresh water whereas, 45.0 and 51.8% respectively with high salinity water (15 dS m^-1) irrigation compared to the non-inoculated plants. Interestingly, best growth was obtained at low fertilizer level. Inoculation coupled with low fertilizer level increased the plant height by 20.4% and trunk diameter by 18.4% over the full fertilizer level. The experimental data showed that date palms should be associated with AM fungi at nursery stage using the inoculants. Plants can then better withstand salinity stress and they are available for field transplanting in comparatively shorter periods saving up to one year in the nursery. The results also showed that date palms will grow better under natural conditions when effectively associated with AM fungi. Also, less chemical fertilizer and inputs are required to grow date palms when they are effectively mycorrhized. The implications of mycorrhizal inoculation with commercial inoculum for date palm production in UAE and in the Arabian Peninsula are discussed.