Developement of micropropagation protocol for jackfruit (Artocarpus heterophyllus Lam.)

Abstract

The present study entitled, “Development of micropropagation protocol for jackfruit (Artocarpus heterophyllus Lam.)” was conducted at tissue culture laboratory, Regional Agricultural Research Station, Pilicode, Kasaragod, during 2018-2020. All the experiments were laid out in completely randomized design. The first experiment was done with the objective to find out the best medium for culture establishment. The treatment combinations include T₁: MS medium with 2 mg/L BA, T₂: ½ MS medium with 2 mg/L BA, T₃: Modified with 2 mg/L BA, T₄: Woody plant medium with 2 mg/L BA, T₅: Gamborge B₅ medium with 2 mg/L BA replicated four times. The result revealed that T1 took minimum days for shoot emergence (13.16), shoot multiplication & branching (15.83), produced maximum no. of shoots/ explant (1.83), Shoot length (1.13cm) and no. of leaves/ shoot (1.66). Second experiment was done with the objective to find out effect of growth regulator for shoot multiplication with 5 treatments replicated four times. The treatment combinations included T₁: Selected basal medium, T₂: Best medium from the 1st experiment, T₃: T₂ + 1 mg/L BA, T₄: T₂ + 2 mg/L BA, T₅: T₂ + 3 mg/L BA. The study clearly indicated that T₃ showed better response in multiplication in terms of minimum days for shoot emergence (13), no. of shoots/ explant (1.99), no. of leaves/ shoot (1.66) and highest shoot length was noticed in T2 (1.13). Another combination of growth regulators were also tried for multiplication with 8 treatments replicated thrice. The treatment combinations included T1 : MS medium + 1mg/L BA + 0.35mg/L GA3, T2 : MS medium + 1.5mg/L BA + 0.35mg/L GA3, T3 : MS medium + 2mg/L BA + 0.35mg/L GA3, T4 : MS medium + 2.5mg/L BA + 0.35 mg/L GA3, T5 : MS medium + 3mg/L BA + 0.35mg/L GA3, T6 : MS medium + 3.5mg/L BA + 0.35mg/L GA3, T7 : MS medium + 4mg/L BA + 0.35mg/L GA3, T8 : MS medium + 4.5mg/L BA + 0.35mg/L GA3. Results shows that MS medium + 2.5mg/L BA + 0.35 mg/L GA3 found to be superior in terms of minimum days for shoot emergence (8.22 days), highest shoot length(2.26 cm), no. of leaves/ explant (4.44) and MS medium + 3mg/L BA + 0.35mg/L GA3 produced maximum no. of shoots/ explant (3.88). Third experiment was conducted with the objective to find out best growth regulator for rooting with nine treatments replicated thrice. Treatment combinations included T₁: ½ strength of selected basal medium, T₂: T₁ + 1 mg/L NAA, T₃: T₁ + 3 mg/L NAA, T₄: T₁ + 0.5 mg/L IBA, T₅: T₁ + 1 mg/L IBA, T₆: T₁ + 1 mg/L NAA + 0.5 mg/L IBA, T₇: T₁ + 1 mg/L NAA + 1 mg/L IBA, T₈: T₁ + 3 mg/L NAA + 0.5 mg/L IBA,T₉: T₁ + 3 mg/L NAA + 1 mg/L IBA. 0.4 g/L of activated charcoal was added to each treatment. None of the treatments produced roots. Another combination of growth regulators were also tried for rooting with eight treatments replicated thrice. The treatment combinations include T₁: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 1 mg/L NAA, T₂: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 3 mg/L NAA, T₃: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 0.5 mg/L IBA, T₄: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 1 mg/L IBA, T₅: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 1 mg/L NAA + 0.5 mg/L IBA, T₆: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 1 mg/L NAA + 1 mg/L IBA, T₇: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 3 mg/L NAA + 0.5 mg/L IBA, T₈: MS + 2.5 mg/L BA + 0.35 mg/L GA3 + 3 mg/L NAA + 1 mg/L IBA. Rooting was not observed in all the treatment. It can be concluded that among the basal medium, MS medium fortified with 2 mg/L BA is good for culture establishment. MS medium fortified with 2.5-3 mg/L BA along with 0.35 mg/L GA3 can be used for shoot multiplication. Rooting was not observed because of basal callus formation and phenolic exudation.