Study On Cold-resistance Of New Weigela Varieties

Weigela florida’Red Prince’and Weigela florida’Gold Rush’are two excellent plants for landscape application. They both have beautiful leaves and flowers. The gold-color leaf of Weigela florida’Gold Rush’is really glorious. But they can not be widely used in Harbin area because of the limitation of their cold-resistance. Heilongjiang Forest Plant Garden have made hybridized breedings between Weigela florida’Red Prince’, Weigela florida’Gold Rush’and local species Weigela florida, Weigela florida f. alba. The hybridized varieties Weigela florida’Royal’and Weigela florida’Ruby’had stronger cold-resistance and better ornamental characters. The study was to identify their concrete cold-resistance for the further application in hard-cold area.Morphologies of the two new hybridized varieties overwintering in outside field were observed. Indicators of relative conductivity, MDA content, SOD activity, POD activity, soluble protein content, soluble sugar content of one-year branches treated at different temperatures were tested. Weigela florida, Weigela florida’Red Prince’and Weigela florida’Gold Rush’were the controls. Methods of variance analysis, multiple comparison and subjection analysis were used to identify comprehensively the cold-resistance of the Weigelas. The results are as follows:1The plants of Weigela florida’Royal’, Weigela florida’Ruby’and Weigela florida overwintering in outside field had no injury during the period of overwintering in Harbin area. The plants of Weigela florida’Red Prince’and Weigela florida’Gold Rush’had different-degree injuries.2The phenological phase of Weigela florida’Royal’and Weigela florida’Ruby’in Harbin area were near to Weigela florida, ahead of10-15days compared with Weigela florida’Red Prince’and Weigela florida’Gold Rush’. Plants of the two new varieties growed vigorously with more glorous flowers and leaves, and the flower period was as long as two months, from middle May to middle July. The gold-color leaves of Weigela florida’Ruby’were from late April to middle October.3Relative conductivity of the five Weigela branches rosed with the temperatures lowing, and the temperature had a significant influence on relative conductivity (P<0.01). The relative conductivity of Weigela florida’Royal’and Weigela florida’Ruby’had no significant difference with Weigela florida, and was significantly lower than Weigela florida’Red Prince’and Weigela florida’Gold Rush’.4The LT50of Weigela florida’Royal’, Weigela florida’Ruby’, Weigela florida, Weigela florida ’Red Prince’and Weigela florida’Gold Rush’were respectively-40.24℃,-39.6℃,-41.59’C,-32.08℃and-30.46℃ 5MDA content of the five Weigela branches showed a rising trend with the temperatures lowing, and the temperature had a significant influence on MDA content(P<0.01). MDA content of Weigela florida was the lowest, then the two new varieties, and Weigela florida’Red Prince’and Weigela florida’Gold Rush’were higher. There was significant difference between the three groups.6With the temperatures lowing, SOD and POD activity of the five Weigela branches rose in the beginning then declined, and the temperature had a significant influence on SOD and POD activity (P<0.05). The changing trend of SOD and POD activity of Weigela florida’Royal’and Weigela florida’Ruby’were near to Weigela florida, and were significantly higher than Weigela florida ’Red Prince’and Weigela florida’Gold Rush’.7The changing trend of soluble protein content of Weigela florida’Royal’and Weigela florida ’Ruby’were concordant with Weigela florida, and showed a rising trend with the temperature lowing. Soluble protein content of Weigela florida’Red Prince’and Weigela florida’Gold Rush’rose in the beginning then declined. The temperature had no obvious effect on the change of soluble protein content.8The change trend of soluble sugar content of Weigela florida’Royal’and Weigela florida’Ruby’ were concordant with Weigela florida, and showed a rising trend with the temperature lowing. Soluble sugar content of Weigela florida’Red Prince’and Weigela florida’Gold Rush’ rose in the beginning then declined. The temperature had a significant influence on soluble sugar content(P<0.01). The soluble sugar content of Weigela florida’Royal’and Weigela florida ’Ruby’were significantly higher than Weigela florida’Red Prince’and Weigela florida’Gold Rush’.9Relative conductivity was positively correlative to MDA content, and negatively correlative to soluble sugar content. Relative conductivity, MDA content and soluble sugar content could be used as the main indicators for cold-resistance identification of Weigelas. SOD activity, POD activity and soluble protein content could be used as the auxiliary indicators.10The order of cold-resistance of the five Weigelas was:Weigela florida> Weigela florida’Royal’> Weigela florida’Ruby’> Weigela florida’Red Prince’> Weigela florida’Gold Rush’. Cold-resistance of Weigela florida’Royal’and Weigela florida’Ruby’was near to Weigela florida, and was obviously stronger than Weigela florida’Red Prince’and Weigela florida’Gold Rush’.