Seaweed Kappaphycus alvarezii is a pre-eminent commodity in the field of marine and fisheries Indonesia which has been widely cultivated in coastal waters. Currently, the main problem faced by the cultivators is the limited stock of seeds, both in terms of quality and quantity. Selection is one method that is expected to increase the rate of seaweed growth quickly, cheap, easy, bulk, and sustainable.This study aims to determine the effect of selection on the growth of seaweed so that it can be done superior seed production for cultivation purposes. Seaweed cultivation was done in Kulu Village, Wori District, North Minahasa Regency, North Sulawesi by using long line method in April-June 2015. Selection is based on the daily growth rate parameter (DGR) and the selection method refers to the selection protocol that has been developed on K. alvarezii seaweed. Results showed that DGR of selection seedlings were higher (P <0.05) compared to controls, in which DGR of selection reached 5.87%/day, while DGR of control was 1.89%/day. From three seed production cycles (G-1 - G-3), the average DGR resulted from the selection was 5.53%/day and control 2.19%/day. Carrageenan content of selection result is relatively higher (47.66%) than control (31.28%) with mean for three cycle (G-1 - G-3) that is 43.55% for selection and 33.20% for control. Water quality (temperature, salinity, nitrate, phosphate) during the study is still within the appropriate range for seaweed growth. Therefore it is concluded that with the application of the method of seaweed selection can increase the daily growth rate and carrageenan content of seaweed K. alvarezii which directly affects the increase of production both in quantity and quality.

AbstrakBudidaya rumput laut Kappaphycus alvarezii dengan metode vertikultur telah diperkenalkan sejak tahun 2013. Walaupun demikian masih diperlukan kajian ilmiah dalam aspek teknis lainnya untuk dapat meningkatkan kualitas, kuantitas, dan kontinuitas produksi serta pemanfaatan lahan secara maksimal dan produktif. Satu di antaranya adalah perbedaan jarak tanam antar rumpun bibit rumput laut. Tujuan penelitian ini adalah untuk menentukan jarak tanam optimal antara rumpun bibit pada metode vertikultur rumput laut. Konstruksi budidaya menggunakan rakit apung ukuran 10x10 m 2 yang memuat 36 jaring vertikultur berukuran 5x2 m 2 / jaring. Bibit rumput laut dengan bobot awal 50 g diikat pada jaring vertikultur dengan jarak antar simpul pada jaring vertikultur yaitu 15 cm, 25 cm, dan 35 cm. Budidaya rumput laut dilakukan selama 3 kali siklus (1 siklus = 45 hari) dan dilakukan secara berkesinambungan dalam siklus musim tanam. Unit-unit percobaan disusun dengan Rancangan Acak Lengkap (RAL) dengan 3 kali ulangan. Hasil penelitian menunjukkan bahwa laju pertumbuhan harian (LPH) dan kandungan karaginan rumput laut yang ditanam dengan jarak 15 cm, 25 cm, dan 35 cm antar rumpun tidak berbeda nyata (P>0,05). Penerapan jarak 25 cm antar rumpun bibit disarankan untuk diterapkan pada metode vertikultur. Kata Kunci: Jarak tanam, Kappaphycus alvarezii, rumput laut, vertikultur AbstractKappaphycus alvarezii cultivation by the verticulture method has been introduced since 2013. However, scientific studies on some technical aspects are still needed to improve the quality, quantity, and continuity of production and utilization of area in a maximum and productive manner. One of them is the planting distance between seed clumps. The purpose of this study was to determine the optimal planting distance between seed clumps on seaweed verticulture method. Seaweed was cultured using a 10x10 m 2 floating raft containing 36 vertical nets of 5x2 m 2 /net. Seaweed seeds with an initial weight of 50 g were tied to a vertical net with a distance between knot on the verticulture net of 15 cm, 25 cm, and 35 cm. Seaweed cultivation was done for 3 cycles (1 cycle = 45 days) continuously in the cycle of planting season. The experimental units were prepared with Completely Randomized Design (RAL) with 3 replications. The results showed that daily growth rate (DGR) and carrageenan content of seaweed planted with a distance of 15 cm, 25 cm, and 35 cm between clumps were not significantly different (P>0.05). However, it is recommended to apply 25 cm distance between seed clumps in the verticulture method.Key Words : Planting distance, Kappaphycus alvarezii, seaweed, verticulture Pengantar Kebutuhan dunia terhadap rumput laut yang meningkat mendorong meningkatnya kegiatan budidaya, karena panen alami kurang dapat menjamin kepastian produksi yang diperlukan. Eucheuma cottonii merupakan salah satu jenis rumput laut merah (Rhodophyceae) dan berubah nama menjadi Kappaphycus alvarezii karena karaginan yang dihasilkan termasuk fraksi kappa-karaginan (Wenno et al., ...

Seaweed of Kappaphycus alvarezii is generally cultivated by the long line method through the water surface. The verticulture method might be an alternative method by using water column. This research aimed to evaluate the effects of depth on the growth and carrageenan content of K. alvarezii which was cultivated vertically. Cultivation was carried out in the floating raft (10 x 10 m) 2 contained of 36 vertical nets. The size of each net was 5 x 2 m 2 whereas the depth was 0.2, 1, 2, 3, 4, and 5 m. Seaweed seedlings of 50 g was each tied to the vertical nets; the distance between the knot was 20 cm. The results showed that the depth was significantly different to the daily growth rate of K. alvarezii (p<0.05) but did not affect carrageenan content (p>0.05). Therefore, this method might be applied as an alternative method to optimally increase seaweed production in narrow area without affecting seaweed quality.

Tujuan penelitian ini adalah untuk mengetahui pertumbuhan rumput laut Gelidium sp. yang dibudidayakan dengan kantong pada dua metode berbeda yaitu long line dan lepas dasar.Rancangan percobaan yang digunakan yaitu Rancangan Acak Lengkap (RAL) yang terdiri dari dua metode (long line dan lepas dasar) dan dua perlakuan yaitu : 1. Uji coba bobot awal rumput laut (bobot bibit 10 g, 20 g, 30 g, 40 g, 50 g, 75 g, 100 g, dan 125 g) dan 2. Uji coba jarak tanam antar rumpun bibit (10 cm, 15 cm, 20 cm, dan 25 cm). Masing-masing perlakuan diulang tiga kali.Hasil penelitian menunjukkan bahwa pertumbuhan Gelidium sp.menggunakan metode long line dan lepas dasarberpengaruh nyata terhadap bobot awal dan jarak tanam antar rumpun bibit (P<0,05). Pertumbuhan mutlak perlakuan bobot bibit awal terbesar pada metode long line dan lepas dasar sama yaitu pada bobot 125 g. Laju pertumbuhan harian perlakuan jarak tanam antar rumpun terbesar pada metode long line dan lepas dasar pun sama yaitu pada jarak 15 cm.Budidaya rumput laut Gelidium menggunakan kantong pada metode long line dan lepas dasar memiliki teknis yang sama baik dari segi bobot awal dan jarak tanam antar rumpun bibit.