Studies On Cold Tolerance In Tomato (lycopersicon Esculentum)

Tomato was an important vegetable crop, it was cultivated everywhere on the world, but chilling injury occurred in production frequently, especially in protected field. It caused flower drop, abscission of fruits, fruit abnormality, quality drop and so on. In the experiment, some cultivar which had different cold tolerance were selected, physiological, biochemical, anatomical and genetic methods were adopted, the seed germination characters, physio. and bioch. items of seedling, pollen formation, pollination, changes of plant hormone at flower stage and relationship between different stage under low temperature were studied. The main results are as follows:?The appraised index at seed germination stage was germination index at 15 C. The inheritance of low temperature germination was in accordance with additive, dominance and epistatic model. The dominance and epistatic effects were predominance. h2(B)=93 .34%, h2(N)=48.96%, so the breeding to resistant cold at germination stage should adopted heterosis breeding primarily. The wild tomato types had a potential to germinate under low temperature.?With the temperature decreasing, change of POD activity and MDA content showed inverse ?letter; activity of CAT showed ?letter, activity of SOD increased first and then decreased; SFA decreased, USFA increased and so IUFA increased; The soluble sugar content, pro-aa and relatively conductivity rate increased; The soluble protein content decreased.?Low temperature postponed blooming date, decreased pollen viability and percentage of fertile fruit, slowed pollen germination and pollen elongation; Pollen viability was correlated with percentage of fertile fruit significantly. The meiosis was susceptible period to low temperature.?Low temperature increased IAA content, but decreased the ratio of flower to apical point,ZR was similar to IAA. The change of GA was complicate, ABA content increased;Parthenocarpical cultivar had a higher ratio of flower to apical point which more than one atABA and ZR, the ratio was the highest among cultivars at GA and IAA.?The cold tolerance at seedling stage was correlated with that at germination stage significantly, but not correlated with flowering stage. Relatively conductivity rate can be used as a rapid and accurate appraisal index for cold tolerance.?Cold acclimation temperature should be above 10 C, To utilize parthenocarpical cultivar would be a solution for cold injury in tomato production.Doctorate student: Wang PuMajor:Genetics and breeding of cropsTuter:Professor Li Jingfu...