By in vitro culture, increased sucrose concentration and addition of naringenin, myricetin and myricitrin to the culture medium increased CHS activity of Walnut shoots. On the contrary, darkness, privation of sucrose and addition of cerulenin and gibberelic acid to the culture medium decreased CHS activity. Concomittant variations of phenolic compounds have been measured. An auxinic treatment followed by rooting tests of above shoots have shown a correlation between the importance of the root system and a decreased CHS activity of leaves. These observations lead to an easy-to-control model for the study of Walnut rejuvenation.