For the payment of such bonds and the interest thereon, the full faith, credit, and taxing power of the State of Mississippi are hereby irrevocably pledged. If the Legislature finds that there are sufficient funds available in the General Fund of the State Treasury to pay maturing principal and accruing interest of the bonds, and if the Legislature appropriates such available funds for the purpose of paying such maturing principal and accruing interest, then the maturing principal and accruing interest of the bonds shall be paid from appropriations made by the Legislature from the General Fund of the State Treasury. However, if there are not sufficient funds available in the General Fund of the State Treasury to pay the maturing principal and accruing interest of the bonds, or if such funds are available but the Legislature fails to appropriate a sufficient amount thereof to pay such maturing principal and accruing interest as the same becomes due, then there shall be levied annually upon all taxable property in the State of Mississippi an ad valorem tax at the rate sufficient to provide the funds required to pay the bonds at maturity and the interest on the bonds as it accrues.