Breaking Dormancy and Effects of Shade Level and NPK Fertilizer Rates on Yield of Zingiber zerumbet (L.) Smith (Lempoyang)

Zingiber zerumbet (L.) Smith, known as Lempoyang in Malaysia, belongs to the family Zingiberaceae. Previous studies on Lempoyang mainly focused on the chemical properties and biological activities of the rhizome extracts of this plant. Despite the tremendous demand for the rhizomes of Z. zerumbet , there is a lack of information on cultivation practices and a scarcity of planting materials. By using the pre-soaked technique, the challenges posed by Z. zerumbet dormancy can be overcome, obtaining good quality and uniform planting material throughout the year. Besides that, it is also crucial to determine the optimum shade level and NPK fertilizer rates to obtain a high yield and good quality rhizomes of Lempoyang. Six concentrations of 6-benzylaminopurine (BAP, 0, 50, 100, 150, 200, and 250 mg/L) and ethephon (0, 150, 300, 450, 600, and 750 mg/L) were tested to evaluate their effects on breaking rhizome dormancy. Three different shade levels (full sun, 30%, and 50% shade levels) and four combinations of Nitrogen (N), phosphorus (P), and potassium (K) (NPK) fertilizer at different rates were evaluated to study their effects on plant growth and yield performance. The results showed that BAP at 100 mg/L and ethephon at 300 mg/L performed better than the other compound concentrations tested in promoting the breaking of bud dormancy. A significant interaction effect was observed between shade levels and NPK fertilizer rates in all the growth parameters examined, except for the number of tillers per plant. Plants grown under 30% shade with NPK 4 produced the highest rhizome fresh weight, dry weight, and yield, but plants grown under 50% shade with NPK 4 showed the highest plant height and number of tillers per plant.