Kappaphycus alvarezii cultivars selected using a ‘common garden’ approach demonstrate improved performance in on-farm trials leading to farmer adoption in Indonesia

Abstract

A ‘common garden’ experimental approach was used to evaluate the production and carrageenan properties of Kappaphycus alvarezii cultivars collected from ten different locations throughout Indonesia. The evaluation was done with three 45-day culture cycles reproducing the longline cultivation method generally used by Indonesian seaweed farmers. The advantage of the common garden approach is that it isolates genetic variability amongst cultivars by effectively removing the influences of environment and cultivation methods. In the first cycle, four cultivars exhibited high growth rates yielding 146–213 g m −1 compared with others which produced only 23–47 g m −1 . One cultivar, sourced from Mamuju, was amongst the best performing cultivars in all three cycles and demonstrated consistently high survival of clumps (79–88%). The Mamuju cultivar was subsequently provided to seaweed farmers across South Sulawesi, and its performance compared with that of ‘local’ cultivars in on-farm trials at three sites (Barru, Jeneponto and Wajo). Production of the Mamuju cultivar in these trials was higher (24–416%) than that of the local cultivars, as was its carrageenan content (up to 32.3% dry weight). The Mamuju cultivar was subsequently adopted by farmers in four locations and, in interviews conducted ~ 5 years later, farmers identified their continued use of the Mamuju cultivar because of its perceived superior growth and morphology. This long-term program of work began with an experimental evaluation of existing cultivars from across Indonesia. We highlight the value of this common garden approach in identifying cultivars with superior performance for provision to commercial seaweed farms.

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