Kappaphycus alvarezii merupakan tanaman thallus yang tumbuh diperairan bersalinitas asin dan mampu menghasilkan karaginan. kultur jaringan merupakan alternatif yang dapat digunakan para petani rumput laut. metode longline merupakan metode yang paling banyak digunakan petani rumput laut karena bersifat fleksibel dalam memilih lokasi dan biaya. tujuan dari penelitian ini adalah untuk mengetahui pertumbuhan rumput laut varietas bibit kultur jaringan lampung dengan perbedaan waktu triwulan penanaman untuk kegiatan budidaya rumput laut di pantai amal kota tarakan. penelitian ini dilaksanakan pada bulan april 2021 sampai bulan juni 2021. rancangan penelitian kontruksi longline berbingkai, pengikatan dan penanaman serta uji pengamatan pertumbuhan mutlak, laju pertumbuhan spesifik, produksi, tingkat kelangsungan hidup, pengamatan kualitas air kemudian di analisis statistik menggunakan uji duncan dengan taraf kepercayaan 95%, berdasarkan hasil penelitian yang telah dilaksanakan dapat disimpulkan bahwa pertumbuhan rumput laut terbaik terjadi pada bulan juni dengan nilai rata-rata 3.082 gram. berdasarkan produksi rumput laut menunjukkan hasil terbaik di bulan juni yaitu 205.49 (g/m). kata kunci: kappaphycus alvarezii, kultur jaringan, produksi rumput laut

Kappaphycus alvarezii is a thallus plant that grows in salty saline waters and is capable of producing carrageenan. tissue culture is an alternative that can be used by seaweed farmers. the longline method is the method most widely used by seaweed farmers because it is flexible in choosing locations and costs. the purpose of this study was to identify the growth of seaweed varieties of lampung tissue culture seedlings with differences in the time of planted quarters for seaweed cultivation activities at amal beach, tarakan city. this research was carried out in april 2021 - june 2021. the research design for the preparation of framed longline construction, binded and planted as well as absolute growth observation tests, specific growth rates, production, survival rates, water quality observations were then analyzed statistically using duncan's test with a level 95% confidence, based on the results of research that has been carried out, it can be concluded that the best seaweed growth occurred in june with an average value of 3.082 grams. based on seaweed production, the best results were in june, which was 205.49 (g/m). keywords: kappaphycus alvarezii, tissue culture, absol, seaweed production