Studies On Response To Heat Stress And In Vitro Selection Of Heat-Tolerant Variants In Senecio×Hybridus

Cineraria (Senecio × hybridus) is the most popular ornamental plant in the world. Which is an ideal pot-flower for the blossom season of lasting over 2 to 3 months during winter and spring, which covers the New Year and the Chinese Rural New Year, as well as the flower is beautiful and elegant, but the heat-tolerant capability of cineraria is very poor, in the most southern province of china, its seedling survival rate is very low, especially in summer. In order to study the physiological and biochemistry mechanism of cineraria seedling affected by high temperature stress , using the uniform clonal plantlet (their mother genotype were numbered B₁,N₁,N₂,N₃,N₄, Z₁,Z₇ respectively) as materials, effects of heat stress on cineraria were studied, and in order to obtain the new heat-tolerant germ plasm, in vitro culture and plant regeneration and in vitro selection of heat -tolerant variants in cineraria were studied by using different organ as explants,. The main results and conclusions were as follows: 1. Response of physiological and biochemistry of cineraria to heat stressCineraria were tolerant to 30℃ , 35℃ stress for 20 h, almost wilting leaves under 30℃ , 35℃ stress were renew, and the heat-tolerant capability of different germ plasm to 40℃20 h stress were significantly difference, Z₁ which the leaves were smaller, thicker, higher water content and larger stomata index were the strongest, B₁ with bigger, thinner, lower water content and lower stomata index were the weakest, and the heat-tolerant capability of N₁,N₂,Z₇ were N₁>N₂>Z₇; Heat acclimation can enhance the tolerance of cineraria to 40℃stress, and lessen heat injury, lower heat injury index 0.04-0.10; The variation of contents of dissolvable protein and proline concerns the heat-resistant capability of cineraria closely. The relative electrolyte leakage (IL) and the contents of malondialdehyde(MDA) increased follow the stress temperature rising, IL and the contents of MDA in the germ plasm with strong heat-resistant capability were lower than in the germ plasm with weak heat-resistant capability, and activity of superoxide dismutase(SOD) and peroxidase(POD) had a positive correlation with the heat-resistant capability of germ plasm, and IL, the contents of MDA, activity of SOD and POD of the cineraria leaves under high temperature stress were suggested as the indicators of...