Effects of Plant Growth Regulators on Micropropagation of Black Pepper (Piper nigrum) in Commercial-Scales

Abstract

Aim: Black pepper (Piper nigrum) is renowned as a popular spice used to flavor dishes around the world and is also an agricultural export commodity that brings high economic value to many countries. However, traditional propagation methods by seed, cuttings, layering, and grafting reveal many limitations such as the low multiplication coefficient, the low survival rate of seedlings, and especially when there is an outbreak of disease, the ability to control the disease source is exceedingly difficult, leading to the spread of disease. Therefore, an alternative method through apical meristem micropropagation has been applied to contribute to sustainable and disease free pepper cultivars. Propagation by apical shoot meristem gives high propagation efficiency, good and uniform seedling quality, and can be propagated in large numbers in a brief period. Methodology: This study is conducted to contribute to optimizing the process of micropropagation of pepper plants to meet the needs of producing excellent quality seedlings, serving the Vietnamese pepper industry. The two steps in the micropropagation sequence studied in this project are shoot formation and bud cluster multiplication. In this study, we investigate the effects of BA (6-Benzylaminopurine) and NAA (α-Naphthalene acetic acid) in shoot formation. Regenerated shoots were then cultured in MS media supplemented with different combinations of Kinetin (6-Furfurylaminopurine) and NAA in bud cluster multiplication experiment. Results: The results showed that the apical shoot meristem cultured on MS medium (Murashige and Skoog, 1962) supplemented with 0.5 mg L-1 NAA and 2.0 mg L-1 BA was the optimal medium for shoot formation rate (100%). Besides, MS culture medium supplemented with Kinetin 1.5 mg L-1 + NAA 0.5 mg L-1 produced superior results in bud cluster multiplication compared with other treatments (8, 20 buds) after 8 weeks (about 2 months). Conclusion: BA, Kinetin and NAA give important rules on micropropagation of black pepper in commercial-scale.