Effect of Phytohormones on In Vitro Morphogenesis of Citrus Cultivars Using Shoot Tip Explant

Saima Mumtaz, Syed Ijaz Ul Haq, Syed Jahanzaib Rasool, Muhammad Atif, Mehwish Yaseen, Touqeer Ahmad, Muhammad Rizwan


An attempt was made to examine the effect of varied concentrations and combinations of phytohormones on morphogenic response of four citrus cultivars viz., Rough lemon (C. Jambhiri), Kinnow (C. reticulata), Feutrell‘s early (C. reticulate × C. sinensis) and Musambi (C. sinensis) from shoot tip explants. To achieve in vitro shoot regeneration, in vitro maintained healthy shoot tips of four cultivars were excised and positioned on modified MS (Murashige and Skoog, 1969) medium fortifying the following benzylaminopurine (BAP)/Indole acetic acid (IAA) concentrations: 0.5/0.4, 1.0/0.4, 1.5/0.4, 2.0/0.4 and 2.5 mg L-1/0.4 mg L-1. Synergetic effect of BAP with IAA was best found on MS medium containing 1.0/0.4 mg L-1 concentration of BAP to IAA for shoot number/plant (2.25), shoot length (2.52cm) and leaf number/plant (10.58). The shoot multiplication rate was decreased in all four cultivars when BAP concentration was increased from 1.0-2.5 mg L-1. In order to assess the impact of different concentrations of auxins, well proliferated shoots were shifted to the rooting medium ((MS micro & macro elements, 100 mg L-1 myo-inositol, MS vitamins, 2 mg L-1 glycine, 30 g L-1 sucrose and 7.0 g L-1 agar) augmented with varied naphthalene-1-acetic acid (NAA)/ indole-3-butyric acid (IBA) concentrations i.e. 0.5/0.3, 1.0/0.3, 1.5/0.3, 2.0/0.3 and 2.5/0.3 mg L-1. Regenerated shoots started to rooting within 22.25 days, had more number of roots/plant (4.25) and root length (3.35cm) on medium containing 1.0 mg L-1 NAA and 0.3 mg L-1 IBA. Sub or supra optimal concentrations of phytohormones resulted in low plant regeneration in all the four cultivars assessed. It was also found that the morphogenic response was genotype dependent in citrus cultivars


Phytohormones, Citrus, Feutrell’s early, Shoot regeneration, Root induction

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