The ultraviolet (UV) band edge photorefractivity of LiNbO₃:Zr at 325 nm has been investigated. The experimental results show that the resistance against photorefraction at 325 nm is quite obvious but not as strong as that at 351 nm, when the doping concentration of Zr reaches 2.0 mol%. It is reported that the photorefractivity in other tetravalently doped LiNbO₃ crystals, such as LiNbO₃:Hf and LiNbO₃:Sn, is enhanced dramatically with doping concentration over threshold. Here we give an explicit explanation on such seemly conflicting behaviors of tetravalently doped LiNbO₃, which is ascribed to the combined effect of increased photoconductivity and the absorption strength of the band edge photorefractive centers.