| The experiment started in Black Burrant Germplasm Resources Garden and Small Berry Germplasm Resources Laboratory of Northeast Agricultural University in2010-2012years, selecting four kinds of one-year-old Black Currant cutting seedlings C4(R.nigrumL.C4), Black Fung (R.nigrumL. heifeng), Asia Germany(R.nigrumL.yade) and Dai Sha (R.nigrumL.daisha) as test materials, which all had different heat tolerance ability, setting different high temperature (35and42degrees) processing the same time (5d) and the same high temperature (42degrees) stressing different times (3d,5d,7d), with25degrees of normal growth as control, so as to explore the effect of high temperature stress on photosynthesis, chlorophyll fluorescence parameters and physiological and biochemical indexes (included the relative permeability of cell membrane, content of MDA, activity of SOD, POD, CAT, content of proline and soluble protein). The experiment also analysised the principal component of the seven physiological indexes, and screened the related indexes of heat-resistance, so as to provide a theoretical basis for the high quality production and suitable cultivation area of Black Currant. The main experimental results were as follows:1. No matter they were the heat-resistant varieties of Black Fung and C4, or the not heat resistant varieties Asia Germany and Black Sand, the MDA and membrane permeability all increased significantly after high temperature stress of42degrees for7d. The increased amplitude of Asia Germany was the largest, which was higher than the other three varieties significantly. The increased amplitude of heat-resistant varieties black Fung was only1/3of Asia Germany, which indicated that the membrane electrolyte of Asia Germany was massive extravasate under high temperature, the peroxidation degree of membrane lipid became serious, and with the stress time increasing, the damage aggravated.2. The Black Currant produced self protection mechanisms under high temperature stress, No matter under35degrees or42degrees, the activity of antioxidant enzymes (SOD, POD, CAT) all elevated under the initial stress, and the content of osmotic adjustment substance-free proline increased. But there were differences between different varieties, the content of free proline of heat-resistant varieties Black Fung continued to increase under high temperature of42degrees, while the other three varieties began to decreased after the stress with5d, which indicated that the heat-resistant variety could accumulated the content of free proline continuously and finally reduced the damage of high temperature to cells.3. Relative to the high temperature of42degrees, under the temperature of35degrees and stressed the same days of5d, the increased size of the relative permeability of cell membrane, content of MDA, SOD, and the activity of POD enzyme of Black Currant all lessened, which indicated that with the temperature increasing, the peroxidation degree of membrane lipid became serious, the permeability of electrolyte increased, and the membrane system was also seriously damaged. To different varieties, the enzyme activity of Black Fung’s SOD, POD all higher than Asia Germany significantly under high temperatures of35and42degrees, especially at42degrees for5d, the enzyme activity of Black Fung’s POD reached25.00U/g, which was2.7times than Asia Germany’s, all of those showed that the antioxidant capacity of heat-resistant varieties was obvious stronger than the not heat-resistant varieties.4. The high temperature stress had obvious influence on the photosynthetic rate of Black Currant’s leaves, different temperature (35and42degrees) and different varieties differed obviously. Under42degrees, the Pn of Black Currant continued to decline; while under35degrees, the Pn presented trend of first rise then fall. Under35degrees and stressed the third days, the Pn of Black Currant varieties was supreme, which was14.75umolm.-2s-1, while Asia Germany’s was minimum, only4.09umolm.-2s-1.5. Under different high temperature stress, the causes for the deterioration of the Black Currants Pn were different. Under the stress of35degrees, the decline of C4leaves’s Pn was mainly caused by stomatal factors, while the other three varieties was mainly caused by non-stomatal factors. Under the stress of42degrees, the decline of Black Currants Pn was mainly caused by stomatal reasons.6. The high temperature had influence not only on the net photosynthetic rate of Black Currants, but also had influence on the structure of light system Ⅱ significantly. Under the stress of35degrees, the Fv/Fm of Black Currants just had small degree decreased in the early times of stress, which showed that the high temperature had less effect on the structure of light system Ⅱ under high temperature stress of42degrees for7d. While compared with the initialization, under the stress of35degrees high temperature for the seventh days, the Fv/Fm of Black Currants fell by70%, qp fell by50%, ETR fell about20%, which showed that under the high temperature of42degrees, light system Ⅱ was obvious damaged. The NPQ increased by about40%, the heat-resistant variety Black Fung increased by70%, which showed that under high temperature, Black Currants could reduced the high temperature damage to the photosynthetic institutions through heat consumption of releasing excess light energy.7. Using the method of principal component analysis, dividing the seven physiological and biochemical indexes such as the membrane permeability, content of MDA and antioxidant enzymes into two main components, the first main component were the MDA, conductivity and CAT activity, and the second main component were the content of soluble protein and POD activity. The contribution rate of the first principal component was54%, which could be used to evaluate the heat-resistant of Black Currants seedlings. |
PDF Full Text Request