Selection of fast-growing seaweed cultivars in Palawan, Philippines

Abstract

Seaweed farming in Palawan currently involves different local cultivars. At least 12 of these cultivars were successfully grown in an indoor facility employing the branch culture techniques and were sea-out planted in Puerto Princesa Bay since 2015. Six of these cultivars yielded relatively high daily growth rates and were selected for the year-round field-testing experiment to compare the growth rates among cultivars and species, between farming sites, and across seasons from 01 July 2021 until 15 August 2022. Monitoring of cultivars’ daily growth rates (DGRs) was conducted in 100 m2 experimental floating monoline plots in Green Island and Sitio Amogues of the municipalities of Roxas and Taytay, Palawan, respectively. Findings revealed that seaweed DGRs significantly varied among cultivars and species (p = 0.001; p = 0.008). The “spinosum” brown from Puerto Princesa and “sacol” green from Green Island, Roxas had higher DGRs, 4.28% and 4.10%, respectively. Grouping the cultivars per species, the cultivars of Eucheuma denticulatum (L. Burmann) Collins & Hervey had higher DGRs compared to Kappaphycus striatus (F. Schmitz) L. M. Liao and Kappaphycus alvarezii (Doty) L. M. Liao. Spatial and seasonal variabilities in cultivar DGRs were also evident. Four cultivars obtained significantly different DGRs between planting sites. The “tambalang” (p = 0.010) and “magnolia” (p = 0.006) with DGRs of 3.26% and 4.08%, respectively in Green Island Roxas, while the “spinosum” brown from Puerto Princesa (p < 0.001; 4.86% DGR) and San Vicente (p < 0.001; 4.45% DGR) in Amogues, Taytay. Three cultivars in Green Island, Roxas, obtained significantly higher DGRs during the wet season. These were the “tambalang” (p = 0.000; 3.98% DGR), “magnolia” (p = 0.000; 4.57% DGR), and “spinosum”-brown from Puerto Princesa (p = 0.006; 5.23% DGR). In Amogues, Taytay, all six cultivars obtained significantly higher DGRs during the wet season: “tambalang” (p = 0.210; 3.17% DGR); “lakatan” (p = 0.004; 2.69% DGR); “spinosum” brown from Puerto Princesa (p = 0.00; 3.97% DGR); and San Vicente (p = 0.00; 3.39% DGR). A cropping calendar that indicates the fast-growing cultivars to be planted at a particular site and season is provided in this study. This information shall aid local farmers in cultivar selection towards a sustainable seaweed farm management in Palawan.