Heliyon (Nov 2021)
Methods for vegetative propagation of wild enset (Ensete ventricosum (Welw.) Cheesman) that make genotype conservation possible
Abstract
The declining trends in crop wild relative genetic resources in many crop centers of origins including Ethiopia require short and long-term conservation strategies. Enset (Ensete ventricosum) is arguably the most important cultivated food security crop of Ethiopia with dwindling wild stocks. The cultivated enset is propagated clonally through adventitious bud sprouting from the corm after the distraction of the apical meristem. Shoot regeneration in the cultivated enset has been induced by humans and has not been observed to occur naturally. The technique of shoot induction has not been extended to the wild enset. To determine whether the capacity for shoot regeneration existed in wild enset and optimize the technique, a series of experiments were conducted. These involved: (i) sucker production from corms of wild enset with and without apical meristem removal; (ii) sprouting capacity of corms ranging 22–49 cm diameter, with removed apical meristem; and (iii) a factorial experiment involving two populations of wild enset (from Shebena and Getiba localities in Sheka zone), two ways of preparing or cutting the corms: tero and tubo, i.e. cutting the pseudostem at the corm junction and cutting it at 25–30 cm height, respectively, and three extents of parting the corm (whole, half, and quarter) using corms with a diameter of 45 ± 2.9 cm. The experiments revealed that wild enset can be successfully propagated vegetatively in the same way as the cultivated enset. It also revealed that the regeneration process involved callus formation and adventurous bud proliferation from corms only after the apical meristem was removed. Corms of different sizes varied in their capacity for regeneration significantly with a linear increase in regeneration frequency with corm size. With a one cm increase in corm diameter, regeneration frequency increased by 3.138 %. The two populations of wild enset showed non-significant differences in regeneration capacity; however, the achieved regeneration was generally analogous to that observed among cultivated enset clones: whole corms resulted in a longer time to emergence and fewer sucker per corm than split corms. Specifically, halved corms emerged significantly (p < 0.05) earlier (71 ± 9 and 75 ± 7 days, for Shebena and Getiba populations, respectively) than whole corms (120 days). Regeneration frequency was higher (75–100%) for split than for whole corms (33–56%). The highest rate of suckering (94 ± 14 per corm) was achieved from quarter corms prepared by cutting the pseudo-stem at the junction. In conclusion, the adventitious bud propagation technique developed by farmers to propagate the cultivated enset can successfully be used for the clonal regeneration of wild enset. We recommend the adoption of this shoot induction to conserve and maintain the rapidly eroding wild enset genetic resources in Ethiopia. In addition, wild enset plants with promising characteristics may be fixed using the method to enrich the gene pool of the cultivated enset.
