Induction of tolerance by chlorocholine chloride in Sequoia sempervirens seedlings under natural cooling and drought

Two-years-old Sequoia sempervirens seedlings were foliar sprayed once and twice with chlorocholine chloride (CCC) at 0, 100, 500, 1 000, 1 500 and 2 000 mg.l-1. The purpose was to investigate the effect of CCC on the growth and photosynthetic activity of S. sempervirens seedlings under natural cooling and drought in autumn and winter. The findings showed that the increments of plant height and crown diameter were significantly decreased with the increase of chlorocholine chloride concentration, and the increment of root collar diameter, net photosynthetic rate, actual photochemical quantum yield and photosynthetic electron transport rate showed the trend of increasing first and then decreasing, and reached the maximum at concentrations of 1 000~2 000 mg.l-1. There was not a significant difference between two applications and single application. It suggests that 1 000~2 000 mg.l-1 chlorocholine chloride can protect the photosynthetic activity of S. sempervirens seedlings and alleviate the stress induced by low temperatures and drought in autumn and winter.