Abstract
This study was carried out to improve the critical stage of artichoke (Cynara scolymus) micro propagation by using shoot tip of offshoots cv. Herous. After multiplication stage, micro shoots were subjected to pre rooting modified M.S. medium treatments as follow: 100%, 75% and 50% strength of ammonium nitrate and potassium nitrate. either indole butyric acid and naphthalene acetic acid (NAA) at 0. 1.0, 2.0 mg/l and beta-cyclodextrin at 0. 2 and 4 g/l and under darkness and light conditions were studied. A complete randomized design was adopted for all in vitro experiments. Root induction (%), root number, root length (cm) and leaf number/young rooted/shoot were recorded. Also, total phenolic compounds were determined in basal parts of rooted and without rooted micro shoots and anatomical structure of basic part of shoots at rooting stage were investigated. Results indicated that, adding 2.0 mg/l NAA produced the highest root induction % (82.75), root number (1.64) and root length (10.85 cm)/young rooted shoot under darkness conditions. Also, results showed that adding NAA at 2.0 mg/l + beta-cyclodextrin 4g/l under darkness conditions, gave the highest root % (86.80), root number (1.89) and root length (5.64 cm) / young rooted shoot and the least content of total phenolic compounds. Anatomically study on rooting phase indicated that there were no structure differences between rooted and rootless plantlets. It could be concluding that using half strength of ammonium nitrate and potassium nitrate pre rooting MS medium is the superior to obtain the healthy and vigor shoot quality. Also, supplemented with 2.0 mg/l NAA + 4g/l (beta-cyclodextrin under darkness conditions is the best treatment for rooting globe artichoke.