THE INFLUENCE OF ARBUSCULAR MYCORRHIZAL COLONISATION ON KEY GROWTH PARAMETERS OF FIVE CITRUS ROOTSTOCK CULTIVARS UNDER SALT STRESS

A study was conducted to compare the efficacy of mycorrhization on five citrus rootstocks (Poncirus trifoliata, rangpur Lime, Citrus macrophyla, carrizo Citrange and Mandarin cleopatre). The plants were mycorrhized by placing the inoculum (soil+roots) next to the roots. The plants were placed in a greenhouse and irrigated twice a week with a nutrient solution (Hoagland solution). Salt stress was applied by supplementing the nutrient solution with NaCl at three different concentrations (0g/l, 2g/l and 5g/l) for seven weeks. Irrigations were performed twice a week. The experimental setup used was a split-plot. After two months of growth, the plants were harvested and subjected to various analyses to determine biomass (fresh and dry weights), root and plant mass, soluble sugars in the leaves, proline and total chlorophyll. The results obtained show that the response of the rootstocks varies according to the mycorrhization and the salt concentration used. Mycorrhization improved growth in non-stressed plants (with the higher value detected in Citrus macrophyla plants with 36.93cm and 2.20g respectively in linear and root biomass growth). This growth drops significantly in the case of salt stress but remains comparatively higher than that recorded in non-infected plants (linear growth in Mandarin cleopatre in non-infected plant is 10.26cm for 13.93 in infected ones). The comparison of the different parameters measured (morphological and biochemical) allowed us to conclude that the rootstocks differed significantly at 5% under the different NaCl treatments and mycorrhization.