Clovers are amongst important forage crops native to Iran. Salinity is a major constraint to agricultural productions world wide. Salt affected soils of the world are stimates to comprise approximately 20% of areable lands. Salt stress is particulary severe in arid and semi-arid areas of the world including Iran. Rhizosphere microorganisms may enhance the nutritional acquisition ability of many plant species from their soil environment. The latter effect of these microorganisms may vary both with plant species and environmental conditions. VAM mycorrhiza are a major contributor to plant rhizosoheric flora and may influence plant growth through altering nutrient availability of the soil. In order to investigate the effect of mycorrhiza and phosphorus amendment on clovers response to salt stress, a factorial 2-replicate randomized complete block pot experiment was conducted at the Isfahan University of Technology, Iran. Four levels of salinity, consisting, control, 15, 30 and 45mM of NaCl and four levels of mycorrhiza consisting, mycorrhiza, phosphorus, mycorrhiza+phosphorus and control (no mycorrhiza+no phosphorus) were applied on 3 clover species consisting Iranian clover ( Trifolium resupinatum ) , red clover ( Trifolium pratense ) and Egyptian clover ( Trifolium alexandrinum ). Shoot dry mass, SPAD, chlorophyll flourescense, and concentrations were measured in 75-day old plants. Salinity led to significant decreses in shoot dry mass, SPAD, maximum efficiency of PSII and . Maximum flourescense, minimum flourescense and . Decresed with increase in NaCl level. Egyptian clover out-performed the remaining species in terms of SPAD and shoot dry mass. Mean shoot dry mass , maximum efficiency of PSII, maximum flourescense and minimum flourescense of clovers were higher when they were subjected to the mycorrhiza and phosphorus level of mycorrhiza treatment. It may be concluded that NaCl leaves negative impact on clover growth and physiological attributes and magnitude of this effect varies with clover species. Furthermore, mycorrhiza may alleviate the negative effect of NaCl if applied with an appropriate level of phosphorus.
