Abstract: An effective regeneration system is the pre-requisite for genetic transformation of bamboos. Medium components for callus proliferation of Bambusa multiplex were studied, 5 basal medium, 6 organic additives, 7 sugars, and 5 macronutrients were compared. The results showed that Murashige and Skoog (MS) basal medium was effective, callus increased 2.8 times at 20 days, white to yellowish, compact; 1.0 g·L^-1 proline was suitable the organic additive, callus increased 3.64 times, yellowish, compact and even; 30 g·L^-1 maltose was the optimal carbon source, callus increased 2.96 times, white to yellowish, even. Among five macronutrients, NH₄NO₃ has significant influence on callus proliferation (α＝0.05) and its optimal concentration was 825 mg·L^-1, callus could increase over 5 times at 29 days, with some rooting; KNO₃ 475 mg·L^-1+NH₄NO₃ 825 mg·L^-1+MgSO₄·7H₂O 185 mg·L^-1+KH₂PO₄ 340 mg·L^-1+CaCl₂·7H₂O 440 mg·L^-1 is a suitable combination for callus proliferation.

Key words: Bambusa multiplex, callus, proliferation, medium, optimization