Direct formation of axes in new plantlets of Kappaphycus alvarezii (Doty) Doty, as influenced by the use of AMPEP K+, spindle inhibitors, and plant growth hormones

In order to induce the direct formation of erect dark brown vegetative shoots of Kappahycus alvarezii, under micro-propagation conditions, the agricultural bio-stimulant Acadian Marine Plant Extract Powder (or AMPEP) K+ (a Canadian commercial extract of the brown seaweed Ascophyllum nodosum with enhanced levels of potassium) was used singly or in combination with colchicine or oryzalin at different concentrations plus (synthetic) plant growth regulators (i.e., PGR, IAA, and kinetin) over 45 days of incubation. Amongst the treatments tested, 5 mg L-1 AMPEP K+ with PGR produced the longest direct axis shoots (9.6 +/- 0.33 mm), followed by 0.1 mg L-1 AMPEP K+ + 1.0 mg L-1 oryzalin with PGR (8.7 +/- 0.00 mm), 10 mg L-1 AMPEP K+ + 0.5 mg L-1 colchicine with PGR (8.6 +/- 1.20 mm), and 0.5 mg AMPEP K+ only (5.3 +/- 1.8 mm). The shortest, direct axis shoots measured were the following: 8.3 +/- 0.33 mm with 0.1, 1 and 10 mg L-1 AMPEP K+ with PGR, 6.0 +/- 0.58 mm with 0.5 mg L-1 AMPEP K+ + 0.1 mg L-1 oryzalin with PGR, 5.3 +/- 0.89 mm with 0.5 mg L-1 AMPEP K+ + 0.1 mg L-1 colchicine with PGR, and finally, 2.7 +/- 0.33 mm with 0.1 mg L-1 AMPEP K+ only. The percentage of direct shoots formed ranged from 93 to 100 % and 87 to 100 % in AMPEP K+ with PGR and AMPEP K+ only, respectively, while 62-100 % and 87-100 % were observed in AMPEP K+ + colchicine with PGR and AMPEP K+ + oryzalin with PGR, respectively. The use of AMPEP K+ with the PGR resulted in the longest and highest percentage formation of direct axis shoots. These observations, taken together, suggested the efficacy of AMPEP K+ used as a protocol to induce direct, erect shoots for the micro-propagation of K. alvarezii plantlets under laboratory conditions.