Optimization of Sucrose, Plant Hormones and Photoperiod for in vitro Propagation of Lemon (c. limon) and Macrophylla (c. macrophylla) using Shoot Tip

Abstract

Although citrus is an important fruit in Ethiopia, its production is limited by different factors like shortage of planting material and disease transmission. This study was conducted to investigate the combined effect of growth regulators and sucrose concentration for in vitro propagation of citrus using shoot tip. Seeds were extracted from mature fruits and cultured on hormone free MS media in the light and dark condition for initiation. Initiated shoots were cultured in MS medium supplemented with different concentrations of BAP and Sucrose. The treatments arranged in 2x4x4 factorial experiment laid out in CRD with three replications. Macro-shoots were then transferred onto 1/2 MS medium supplemented with different combination of NAA (0, 1, 2, 3, 4, 5 mg/l) for rooting. Statistical analysis revealed that there was highly significantly difference (P<0.01) among all treatments in shoot initiation, shoot multiplication and rooting experiments. Hundred percent shoot initiation was obtained in light condition for lemon. Maximum number of shoots per explant (10 ±0.55) and (7 ±0.0) was obtained from MS medium containing 2.5 mg/l BAP combined with 30 g/l sucrose for lemon and  macrophylla respectively. The highest number of roots per shoot (20.3±0.6) obtained at 1 mg/l NAA for lemon. Among the rooted plantlets used for acclimatization, 65% of them survived. According to the result obtained in this study, shoot initiation in light condition, MS medium supplemented with 2.5 mg/l BAP combined with 30 g/l sucrose for shoot multiplication and 1/2 MS medium supplemented with 1 mg/l NAA for rooting were recommended for in vitro propagation of lemon and macrophylla.

Keywords/Phrases: BAP, NAA, germination, shoot multiplication, rooting