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Saabunud / Received 29.01.2021 ; Aktsepteeritud / Accepted 01.05.2021 ; Avaldatud veebis / Published online 01.05.2021 ; Vastutav autor / Corresponding author: Budi Winarto budi.winarto67@yahoo.co.id Finding optimal shoot growth performances under different treatments and revealing different growth responses of different explant types as main objectives were assessed in the research. Different treatments of 5 000; 8 000 and 11 000 lx in light intensities; 0, 25, 50, 75 and 100 ml l–1 in coconut water (CW) concentrations; culture media (CM) of Murashige and Skoog (MS) medium supplemented with 1.5 vitamin strength in the medium in combination with 100 mg l–1 myoinositol, 1 mg l–1 calcium pantothenate (CaP), and 0.1 mg l–1 gibberellic acid-3 (GA3) (CM-1); 200 mg l–1 myoinositol, 1 mg l–1 CaP dan 0.1 mg l–1 GA3 (CM-2); 1 mg l–1 CaP and 100 ml l–1 CW (CM-3); and MS medium supple-mented with 1.5 total vitamin strength in the medium (CM-4 as control) and shoot tip, first, second, third, fourth and fifth nodes as explant types were gradually tested in the research. Virus-free Solanum tuberosum L. 'Muhzoto' explants and MS medium containing 1.5 strength of vitamin were used as explant source and basic medium. Four experiments were arranged in a completely randomized design (CRD) with 6–9 replications. Maximal shoot growth performances indicated by shoot height, stem diameter, internode length, greener leaves per shoot, leaf length and width were established in explants incubated under 11 000 lx light intensity applied continuously. Adding different concentrations of CW could not improve the growth of shoots, but they induced high contamination. Though MS medium containing 1.5 vitamin strength with 200 mg l–1 myoinositol, 1 mg l–1 CaP and 0.1 mg l–1 GA3 slightly improved shoot growth, there was no significant difference compared to control. Exploring shoot growth responses derived from different types of explants revealed that the shoot tips, 1st and 2nd nodes regenerated high branched shoots with the higher length of internodus; while 3rd, 4th and 5th nodes stimulated low branched shoots with higher stem diameter and the number of leaves per shoot. The branched shoots were a serious problem in preparing high-quality regenerants for 'Muhzoto' explants and significantly overcome by choosing, selecting and applying the right time on subculturing of the 'Muhzoto' explants. |
