Paclobutrazol and sucrose boost tuber size and survival rate of micro propagated Zantedeschia spp

Abstract

Micropropagation of Zantedeschia, commonly known as Calla lily, represents a valuable and economically feasible method for plant propagation. However, the success of in vitro cultivation is heavily dependent on the proper formation of tubers, as plants lacking well-developed tubers face reduced survival rates during subsequent transfer and acclimatization stages. This research aimed to investigate the effects of varying concentrations of sucrose, cycocel, and paclobutrazol on the size and production of microtubers in potted Zantedeschia cultivars, specifically Sun Club, Orania, and Zazu, under in vitro conditions. The study was conducted as two separate experiments using a completely randomized design. In the first experiment, the Zantedeschia cultivars were exposed to various concentrations of sucrose (3%, 6%, and 9%) combined with different concentrations of cycocel (0, 150, 200, and 250 mg/l). The second experiment involved the same sucrose concentrations combined with paclobutrazol (0, 0.5, 1.5, and 3 mg/l). The results indicate that Zantedeschia cultivars demonstrate varying responses in survival rates and tuber sizes following acclimatization. The control group exhibited survival rates of 40% for Sun Club, 32% for Orania, and 53% for Zazu, along with corresponding tuber sizes of 23.91 mm, 25.71 mm, and 20.55 mm, respectively. Notably, the application of 6% sucrose in combination with 0.5 mg/L paclobutrazol significantly enhanced survival rates to 86% for Sun Club, 80% for Orania, and 91% for Zazu, while also increasing tuber diameters to 48.72 mm, 50.41 mm, and 44.06 mm, respectively. These findings contribute to develop an efficient micropropagation protocol for the Calla lily by enhancing tuber size to improve survival rates, thereby addressing a critical bottleneck in its propagation.

Keywords: Calla lily; Growth retardants; Ornamental plant; Plant tissue culture; Tuber formation.

Fig. 1

Comparison of calla lily micro tubers growth in in vitro condition after using paclobutrazol and sucrose. Left: Control treatment (3% sucrose) including Sun Club, Orania and Zazu respectively and Right: 0.5 mg/L paclobutrazol with 6% sucrose treatment including Sun Club, Orania and Zazu respectively. Scale Bar: 20 mm.

Fig. 3

Comparison of calla lily micro tubers growth in the first period of dormancy (three months after acclimatization). Left: Control treatment (3% sucrose) including Sun Club, Orania and Zazu respectively and Right: 0.5 mg./L paclobutrazol with 6% sucrose treatment including Zazu, Sun Club and Orania respectively. Scale bar: 20 mm.

Fig. 2

Comparison of quality of calla lily acclimatized plants after plantlets transfer to ex vitro condition in two months later. Left: control treatment (3% sucrose) including Sun Club, Orania and Zazu respectively and Right: 0.5 mg/L paclobutrazol with 6% sucrose treatment including Zazu, Sun Club and Orania respectively. Scale bar: 6 cm.