Study On Physiological Characteristics Of Drought Resistance And Fruit Quality Of Blackcurrant

This study combines the century light and century star pot varieties of Ribes nigrum L.with experimental test materials in a field experiment. The pot experiment seedlings weretreated with3different gradients of soil drought. The relative water content of the soil wasmaintained at80%(CK)，60%(mild stress)，and40%(moderate stress) for30days to studythe biological drought resistance indexes of Ribes nigrum L. and photosyntheticcharacteristics respectively．The field experiments used the century light and century starplants cultivated in Xinjiang Agricultural University’s Three Ping Farm Field．Regularsampling was conducted to determine the related indexes of quality fruit．１．The results showed that the relative water content of the soil was80%under ordinaryconditions．The free proline in century light and century star of Ribes nigrum L. along withthe soluble protein content，K+content，the cytomembrane permeability，the leaf relative watercontent，SOD，POD，CAT activity，MDA，O2-.，and H2O2content were all remained in stablecondition after the30day mild treatment of60%soil moisture content．Under moderatetreatment of40%soil moisture content，the proline content in century light and century starand the soluble carbohydrate content of K+，and a kind of osmoregulation substanceincreased．However，the leaf relative water content and soluble protein content decreasedï¼›SOD，POD，and CAT enzyme activities increased．MDA，O2-. and H2O2content alsoincreased．In century light，the free proline and soluble sugar levels in the osmoregulationsubstance were more than that of the century star．Also，century lights’s increase in SOD，POD，and CAT was greater than that of century star．The levels of MDA, O2-.，and H2O2inthe leaves of century star were more than that century light．Leaf relative plasmalemmapermeability increased with the soil drought stress and was gradually aggravated bytime．Under mild stress treatment after30days，the relative permeabilities of the plasmamembranes for the two varieties were not more than20%and there was no fatal damage．Under moderate stress treatment on the twenty-fourth day，century light had a plasmamembrane relative permeability of more than50%，while the century star’s was more than50%on only the eighteenth day and reached the half lethal level．There was a significantdifference between the level of each soil drought (P<0.01)．In century light leaves，effectiveosmolyte proline and soluble sugar content，as well as protection enzymes’(SOD，POD，CAT)activity increased，while the amount of MDA，reactive oxygen species，the relativepermeability of plasma membrane，as well as enhanced the water retention ability alldecreased．This shows that century light’s drought resistance is stronger than that of centurystar．ï¼'．At80%relative soil water content，photosynthesis changes．The net photosyntheticrate，the diurnal variation of transpiration rate，and utilization of water rate all presented asingle peak corresponding with the photo index．But，under mild and moderate stress，thesethree rates gave two peaks，rising and falling twice during the course of the day．The averagephotosynthetic rate under the mild stress treatment measured on clear days and the diurnalvariation of transpiration rate in century light were more than that of century star by6.72%，61.13%，respectively．Century light’s water consumption was less than that of century starby36.18%．The average photosynthetic rate under moderate stress treatment throughout cleardays and the diurnal variation of transpiration rate in century light were more than that ofcentury star by9.85%，37.32%，respectively．Century light’s water consumption undermoderate drought conditions was less that that of century star by44.63%．３．The5different period sampling and measurements of Ribes nigrum L. century lightand century star fruit quality study found，the century light and the century star fruit solublesugar content and vitamin C content was constantly increasing，while the organic acid contentdecreased．In the fully ripe fruit，the soluble sugar content，vitamin C content and organic acidin the century light fruit were higher than the century star by22.05%，24.40%，16.03%，respectively．...