Pengaruh Kombinasi 2,4-D dan BAP terhadap Induksi Kalus Jeruk Sitrun (Citrus limon L.)

Abstract

Lemon (Citrus limon L.) is a horticultural crop with high economic value and is widely utilized in the food, health, and cosmetic industries. Conventional propagation still faces several constraints, particularly the availability of uniform seedlings, propagation efficiency, and the risk of disease contamination; therefore, an alternative method through tissue culture is required. One important stage in tissue culture is callus induction, whose success is influenced by the balance of plant growth regulators, particularly auxins and cytokinins. This study aimed to determine the in vitro callus induction response of lemon to several levels of 2,4-D and BAP combinations and to identify the most effective plant growth regulator combination. The study was conducted at the Tissue Culture Laboratory, Faculty of Agriculture, Universitas Negeri Gorontalo, using in vitro lemon seedling explants consisting of cotyledons, hypocotyls, and epicotyls. A non-factorial Completely Randomized Design was used with four treatments: M0, MS medium without plant growth regulators; M1, 1 mg L⁻¹ 2,4-D + 1 mg L⁻¹ BAP; M2, 2 mg L⁻¹ 2,4-D + 2 mg L⁻¹ BAP; and M3, 3 mg L⁻¹ 2,4-D + 3 mg L⁻¹ BAP, with each treatment replicated three times. The observed parameters included the time of callus emergence, percentage of callus growth, and callus morphological characteristics. The results showed different responses among treatments. The fastest callus emergence was observed in M1, at 15.33 ± 3.59 days after inoculation, whereas the longest was recorded in M3, at 20.40 ± 2.00 days. The highest percentage of callus growth was obtained in M1 at 44.64%, followed by M3 at 41.11% and M2 at 31.64%. The callus was generally compact in texture, with colors ranging from yellowish white to brownish yellow. The combination of 1 mg L⁻¹ 2,4-D and 1 mg L⁻¹ BAP was the best treatment under in vitro conditions.