[On the best time for harvesting Dendrobium candidum Wall. ex Lindl].

OBJECTIVE: To explore the theory on the best time for harvesting Dendrobium candidum so that the production of the herb can be directed more effectively.
METHOD: Based on a component analysis in combination with mathematical calculation, a synthetical appraisal on the yield, contents of effective components and efficacy of D. candidum in different growing periods has been made, and different appraisal indexes and synthetical harvesting indexes have been worked out. RESULT: The harvesting indexes from the first year to the fourth year are as follows: 5.69, 9.54, 17.9, 22.2 (curing throat and eye diseases); 11.2, 14.6, 21.6, 17.6(strengthening immunity); 8.44, 12.1, 19.7, 19.9(the above-mentioned indexes and yield factor considered together).
CONCLUSION: The best time for harvesting D. candidum is in the fourth year for curing throat and eye diseases; in the third or first year for strengthening immunity; and in autumn of the third year if the above-mentioned indexes and yield factor are to be considered together.