Effects of Exogenous Salicylic Acid on Nitrate Accumulation and Reduction and Assimilation in the Leaves of Chinese chive Effects of Exogenous Salicylic Acid on Nitrate Accumulation and Reduction and Assimilation in the Leaves of Chinese chive Effects of Compound Sodium Nitrophenolate on Growth and Nitrate Reduction and Assimilation in the Leaves of Chinese Chive