[Responses of mulberry seedlings photosynthesis and antioxidant enzymes to chilling stress after low-temperature acclimation].

Taking the seedlings of mulberry (Morus alba) variety 'Qiuyu' as test materials, this paper studied the changes of their leaf photosynthesis and antioxidant enzymes during low-temperature acclimation, chilling stress, and normal temperature recovery. The results showed that low-temperature acclimation at 12 degrees C for 3 days markedly increased the cold resistance of mulberry seedlings. After the acclimation, the leaf net photosynthetic rate (P(n)), stomatal conductance (G(s)), and maximum photochemical efficiency of photosystem II (F(v)/F(m)) under the chilling stress at 3 degrees C for 3 days increased obviously and recovered rapidly, compared with the control non-acclimation. During the period of the low-temperature acclimation and chilling stress, the leaf proline and soluble sugar contents increased. After the acclimation, the leaf malondialdehyde (MDA) content was obviously lower while the leaf ascorbate peroxidase (APX) activity was obviously higher than the control, illustrating that the increase of osmolytes content and APX activity played important roles in the cold resistance of mulberry seedlings.