Stimulatory effects of aluminum on the growth of cultured roots of tea

Abstract

The effect of Al on the growth of excised tea (Camellia sinensis L.) roots differentiated from stem segments in vitro was investigated in shaking liquid culture.

1) The optimum initial pH for tea root growth in modified MS medium was 5.5. Growth of main and lateral roots was affected by the difference in NAA concentrations. Main root growth was stimulated by 5×10^-7 and 1×10^-6 M NAA, and lateral root growth was stimulated by 5 × 10^-6 and 1 × 10^-5 M NAA.

2) Main root growth showed a progressive increase for 3 weeks, then became stationary. Lateral roots began to grow at 2 weeks, with a progressive increase over the following 6 weeks.

3) The growth of the tea roots in the main or lateral root growth medium was stimulated by the supply of Al and P together, but was not affected when Al and P were supplied separately.

4) The pH of the culture medium decreased gradually to about 4.0 during the shaking culture, and remained stable. Growth of roots supplied with Al was stimulated after the decrease of medium pH, but when the Al supply ceased, growth stopped.

Key Words:

• aluminum
• cultured roots
• low pH
• phosphorus
• tea plants