Adaptability And Low Temperature Stress Of Different Peony Cultivars In Open Field Adaptability Evaluation

Peony is known as the king of flowers,but there is no natural distribution of peony in Northeast China.In order to better introduce peonies in Northeast China,selecting varieties with good adaptability to low temperature environment is the key to successful introduction.Fourteen peony varieties introduced in Shenyang were studied and their plant growth,flowering traits and indexes related to photosynthetic capacity were measured after overwintering in open field cultivation to evaluate the adaptability of open field cultivation.Three 15-20 cm long branches of each peony species were intercepted and placed in sealed plastic bags in a low temperature incubator(LRX-580B-LED)with a light level of 2400 Lx for low temperature stress,with treatment gradients of 5°C,0°C,-5°C and-10°C for 24 h.The physiological indexes were measured by taking the leaves located in the middle and upper part of the branches.Each index was repeated three times for low temperature acclimatization evaluation.Paraffin sections of the leaves of some varieties with different levels of acclimatization were selected to study the relationship between the anatomical characteristics of the leaves and their cold resistance.The results of the study are as follows.I.Adaptability evaluation of open field cultivation1.14 peony varieties sprouted in early spring between April 18 and April 24.The varieties with early sprouting time included Guifeichacui,Huihe,Fenjinyu,Huawang and Taohuayushuang;those with middle sprouting time included Daojing,Juanyehong,Morunjvelun and Jinge;those with late sprouting time included Caozhouhong,Heilongtan,Xiongmao,Juhesanbian and Xinshiji.2.The net photosynthetic rates(Photo)of different varieties under open field cultivation conditions were ranked in order of magnitude: Huawang >Taohuayushuang > Xinshiji > Guifeichacui > Xiongmao > Caozhouhong >Morunjvelun > Jinge> Juanyehong > Fenjinyu > Huihe > Heilongtan > Juhesanbian >Daojing.3.14 peony varieties were evaluated under the open field cultivation conditions according to the hierarchical analysis method,and the results of which were: those rated as III: Huawang,Xiongmao,Juhesanbian and Heilongtan;those rated as II:Juanyehong,Morunjvelun,Xinshiji,Huihe and Daojinh;those rated as I:Caozhouhong,Jinge,fenjinyu,Guifeichacui and Taohuayushuang.II.Evaluation of low temperature adaptability1.Changes in physiological indicatorsCompared with the control,the Rec and MDA of all varieties increased,but the rising trend was different.-5℃ compared with 0℃.the relative conductivity(Rec)of all 14 varieties of peony increased significantly(P<0.05),and the beginning of a sharp rising trend of each variety indicated that the low temperature stress had caused serious damage to the cell membrane,resulting in a large amount of electrolyte extravasation;the rising trend of MDA became larger in most varieties from-5℃ to-10℃.5℃ to-10℃,and this sharp rising trend indicates that under low temperature stress,the cell membrane peroxidation is serious,which leads to the accumulation of MDA,and also,indicates that the cell membrane is seriously damaged.Translated with www.Deep L.com/Translator(free version)The low temperature stress effectively induced the increase of soluble sugar(SS)of each peony species,and the content of soluble sugar(SS)of each species increased significantly(P < 0.05)under all low temperature treatments compared with CK.The soluble protein(SP)content of all varieties,except Guifeichacui,decreased significantly(P < 0.05)compared with CK.The proline(Pro)content of the varieties Panda,Guifeichacui,Xinshiji and Juanyehong increased significantly(P < 0.05)compared to CK,among which the increase was greater in Guifeichacui and showed a pattern of gradual increase in content with temperature reduction.The SOD activity of all species except Huihe increased significantly(P < 0.05)compared with CK.2.The cold resistance of each variety was ranked from strong to weak by the subordinate function method as follows: Guifeichacui > Fenjinyu > Juhesanbian >Juanyehong > Jinge > Daojing > Taohuayusahung > Huawang > Heilongtan >Morunjvelun > Huihe > Caozhouhong > Xinshiji > Xiongmao.3.The five varieties studied were ranked according to leaf tightness index as,Guifeichacui > Juanyehong> Huihe > Jinge > Heilongtan.This ranking result is more consistent with the comprehensive ranking of the affiliation function of physiological indicators under low temperature stress and the comprehensive evaluation of growth and ornamental indicators after overwintering in the open field.Comparing the results of the hierarchical analysis method of evaluation of open field cultivation and the affiliation function method of evaluation of cold resistance,the commonalities were identified and the following conclusions were drawn: In Shenyang,the well-adapted varieties are Guifeichacui and Fenjinyu,which are recommended to be introduced as a priority.The middle ones are Juanyehong and Daojing;the less adaptable ones are Xiongmao and Heilongtan.