OBJECTIVETo study the suitable growth density and the optimal harvest time of Tribulus terrestris.

METHODFour growth densities were set with 60 cm breadth ridge and individual distance of 10, 20, 30 and 50 cm. The yield per individual and per unit area under the different growth densities were determined. Using yam saponin as a standard substance, the total saponin of T. terrestris was determined by UV spectrophotometry.

RESULTThe individual yield decreased with the density increase, but the difference between 30 cm and 50 cm individual distance was not substantial. The yield per unit area increased with density increase, and the difference between all densities was significant. The yield peak was in the last ten-day of August. The best leaves area index was 1.4 at the growth peak time. The total saponins content reached peaks respectively in the last ten-day of June and August, but the peak in last ten-day of August was consistent with the one of yield per unit area, and the total ashes content was the lowest at the same time.

CONCLUSIONThe suitable growth density is 10 cm individual distance on the 60 cm breadth ridge. The optimal harvest time is in the last ten-day of August. The yield per unit area is 1 400 - 2 000 kg x hm(-2).