Screening And Application Of Cold Resistant Germplasm Materials In Brassica Napus.L.

Brassica napus is one of the major oil crops in China.In addition to oil,it can also be used for vegetables,fodder,fertilizer and honey.And for plant breeders,the use of heterosis is the most common breeding method.In China,Brassica napus.L.(n=19)is formed by natural hybridization with Brassica oleracea(n=9)and Brassica campestris(n=10).Brassica napus,holding low erucic acid,low glucosinolates and high oil content,has been sought after by the society.However,its cold resistance is not as good as that of Brassica oleracea.Therefore,it is necessary to screen out new materials with strong cold resistance to provide a new way for breeding work.In this research,4 materials of H1,H2,H3 and H4,provided by rapeseed research group of agricultural college.DAB staining,related physiological and biochemical enzymes(CAT,POD,SOD,ASA-POD)activity were measured in the young leaves at seedling stage,then the comprehensive analysis was carried out to identify cold-resistant materials..We had the results show that the cold resistance of different materials is H1>H2>H3>H4.Hybrid combination had formed by screening results.Due to the worst cold resistance of H4,it was abandoned with the hybrid combination.Thus,there were 3 hybridized combination,H1×S01,H2×S02,H3×S03.Then,low temperature treatment had been used in harvested hybrids.At low temperature of 20 ?,10 ? and 5 ?,the germination status,germination index(GI)and seedling vigor index(SVI)of the three hybrids were calculated.As the results,there are 5 conclusions in the following paragraph:1.DAB staining,which could calibrate the active oxygen production site.And brown spots had generated at the site.The area from large to small was H1>H2>H3>H4.Generally,the oxidation resistance is positively correlated with the area size.The cold resistance is H1>H2>H3>H4.2.The activity of CAT,POD,SOD and AsA-POD were measured for H1,H2,H3 and H4.Under different low temperature stress,the activity of CAT,POD,SOD and AsA-POD would increase first and then decrease.The activity of enzyme reflected the resistance of rape to cold stress.The activity of the four enzymes was H1>H2>H3>H4,and the cold resistance was H1>H2>H3>H4.3.Among 4 materials,the activity of SOD did not increase due to the low temperature.And it may be inhibited by other enzymes in the whole enzyme system,resulting in a decrease sensitivity to low temperature.In the whole Brassica.napus tissue,SOD mainly existed in the chloroplast.When the temperature was lowered,the chloroplast has been damaged,resulting in the loss of SOD.This caused the SOD activity in the measurement results to be insensitive to low temperature.4.Among the three hybrid combination,the germination rate of the hybrid offspring under the treatment of(20°C,10°C,5°C)was H1×S01>H2×S02>H3×S03.5.Three hybrid combinations prepared with three cold-resistant materials were used for field planting,and the results showed that combination H1×S01 showed creeping growth,small stomatal area,developed root system and strong growth at seedling stage.After overwintering,the field fatality rates of H1×S01,H2×S02 and H3×S03 were 1%±0.65,15%±0.83 and 20%±0.42,respectively.The germination of hybrid offspring indicated that the use of cold-resistant materials as parents could improve the cold resistance of hybrid offspring.