One of the problems in the cultivation of K. alvarezii seaweed is that the seeds come from the results of previous cultivation which is used repeatedly and continuously so that the quality of seeds decreases. Efforts to increase seaweed production are using superior seeds, namely seedlings from tissue culture. Therefore, a multi-site test of tissue culture seaweed seedlings was conducted in Maluku Tengara Regency (Evu Village) and Tual City (Fiditan Village) to determine growth rate, gel strength and viscosity. The study involved planting tissue culture and local seaweed seedlings using the longline method in both locations for 45 days. Wet weight samples were measured every 15 days, and at the end of rearing, seaweed was harvested and dried to test gel strength and viscosity. The results of data analysis showed that the growth rate of tissue culture seaweed seedlings was better in both locations, the highest value at the location of Fiditan Village, Tual City at 5.61%/day. Likewise, the gel strength and viscosity of seaweed K. Alvarezii tissue culture seeds are higher than local seeds, where the highest gel strength is obtained in the waters of Evu Village, Southeast Maluku Regency, namely 165.5 g/cm2, while the highest viscosity is obtained in the waters of Fiditan Village, Tual City, namely 136.05 cP. So it is concluded that tissue culture seaweed seeds produced by the Marine Aquaculture Center Ambon are better than local seeds. ABSTRAK Salah satu permasalahan dalam budidaya rumput laut K. alvarezii adalah bibit berasal dari hasil budidaya sebelumnya yang digunakan secara berulang dan terus menerus sehingga kualitas bibit menurun. Upaya untuk meningkatkan produksi rumput laut adalah menggunakan bibit unggul yaitu bibit hasil kultur jaringan. Oleh karena itu, dilakukan uji multi lokasi bibit rumput laut kultur jaringan di Kabupaten Maluku Tengara (Desa Evu) dan Kota Tual (Desa Fiditan) untuk mengetahui laju pertumbuhan, kekuatan gel dan viskositas. Penelitian ini mencakup penanaman bibit rumput laut kultur jaringan dan lokal dengan metode longline di kedua lokasi selama 45 hari. Sampel berat basah diukur setiap 15 hari, dan diakhir pemeliharaan dilakukan panen rumput laut untuk dikeringkan sebagai bahan uji kekuatan gel dan viskositas. Hasil analisis data menunjukan bahwa laju pertumbuhan bibit rumput laut kultur jaringan lebih baik di kedua lokasi, nilai tertinggi di lokasi Desa Fiditan Kota Tual sebesar 5,61 %/hari. Begitu juga dengan Kekuatan gel dan viskositas rumput laut K. Alvarezii bibit kultur jaringan lebih tinggi dibandingkan bibit lokal, yang mana kekuatan gel tertinggi diperoleh di Perairan Desa Evu Kabupaten Maluku Tenggara yaitu 165,5 g/cm2, sedangkan Viskositas tertinggi diperoleh di perairan Desa Fiditan Kota Tual yaitu, 136,05 cP. Sehingga disimpulkan bibit rumput laut kultur jaringan hasil produksi Balai Perikanan Budidaya Laut Ambon lebih baik di bandingkan dengan bibit lokal setempat. Kata Kunci: Rumput laut, kultur Jaringan, laju pertumbuhan, kekuatan gel, viskositas