Studies On Genetic Diversity And Photosynthetic Characters During Bud Stage Of Oil-utilized Safflowers

Safflower(Carthamus tinctorius L.) has been grown commercially for edible oil, medicinal materials and dye sources around the world for centuries.As safflower is more drought and salt tolerant than some other oil seed crops,it has been planted all over the world.Actually,safflower has been planted in China for centuries and Sichuan province is one of famous safflower cultivated areas for flower utilization, but not for oil utilization.Safflower oil main contains linoleic acid(18:1),which account for about 70%-89%of the total fatty acids.High-linoleic safflower oil once largely used in the preparation of paints alkyd resins,varnishes and automobile finishes.Currently,in view of its reported role in reducing blood cholesterol levels,it is being utilized as premium edible oil.In this research,87 safflower accessions were introduced into Sichuan province, the main agronomic characters,the contents of oil and fatty acids of seed oil,and the relationships of these characters were analyzed.The genetic diversity of gliadin of safflower seeds was detected by A-PAGE technology.Photosynthetic characteristics of the leaves at the different positions in three safflower varieties were monitored using portable LI-6400 photosynthesis system.The main results showed as following:1.Using A-PAGE(Acid-polyacrylamide gel electrophoresis),genetic diversity of prolamine was analyzed among 79 safflower accessions.The abundant variations of prolamine were observed,and 15 prolamine bands were detected,ranging from 5 to 12 bands per accession with the average of 8.5.The genetic similarity(GS) varied from 0.1333 to 1,with the average of 0.5303.The diversities among continents were more abundance than inter-continents.At the GS 0.512 level,all accessions were clustered into 4 groups.It suggested that there were some correlations between the cluster results based on prolamine bands of C.tinctorius and geographical distribution, but not significant.2.The results of the effects of main agronomic traits on the seed yield per plant by using correlation and path analysis showed that the affected order of these factors to seed yield per plant was as follows:number of effective cones per plant,number of total cones per plant,number of non-effective cones per plant,100-seed yield,number of total branches,number of secondly branches,number of primary branches,plant height,diameter of cones.Multiple regression analysis showed that number of effective cones per plant,number of total cones per plant,number of non-effective cones per plant,100-seed yield and diameter of cones were the main traits affected seed yield per plant.The number of effective cones per plant and number of total cones per plant had more direct effect to the seed yield per plant.Both of them were the focus on the high yielding breeding and cultivation of safflower varieties.Totally, the high yield oil-utilizated safflower varieties should be more number of effective cones per plant and number of total cones per plant,less number of none-effective cones per plan,higher 100-seed yield and diameter of cones,moderate plant height and number of branches.3.The results of the analysis on the contents of oil and fatty acids of seed oil showed that safflower presented great variability for the contents of seed oil and fatty acids. As compared with the data obtained in GRIN,the oil contents decreased significantly as safflower accessions introduced to Ya an,but the contents of each fatty acid changed a little,the significant difference was just found in the content of palmitic acid.There was significant correlation between the contents of palmitic,oleic and linoleic acid.All the correlation coefficients between the contents of the oil and each fatty acid were insignificant.Most of the correlation coefficients between agronomic traits and fatty acids were insignificant.4.Photosynthetic characteristics of the leaves at the different positions in three safflower varieties were monitored using portable LI-6400 photosynthesis system,and correlations among the net photosynthesis rate and the yield,agronomy characters were analyzed within 16 safflower varieties from 7 different countries.The results showed that the maximal photosynthesis rate(P_nmax),light compensation point(LCP), light saturation point(LSP),dark respiration rate(R_d),apparent quantum yield(AQY) were in the order of upper leaves＞middle leaves＞lower leaves.Lightphotosynthesis curves indicated that the photosynthetic rate of all the leaves decreased significantly under the high light intensity except the upper leaves of PI401470 and Chuan hong No.1.And under the low light intensity,there was no marked difference between the photosynthetic rates of the leaves at the different positions,but as the PFD exceed 400μmolm^-2 s^-1,the photosynthetic rate of the upper leaves was significantly higher than the lower ones.The diurnal variation pattern of photosynthesis in the leaves at the different positions and varieties were different,the time and the value of the peaks were also different.Diurnal changes of the photosynthetically available radiation,air temperature,relative humidity,vapor pressure deficit and CO₂ concentration in the air were all one-peak curve.The ecological factors affecting the P_n could be ranked,from the highest to the lowest,as PFD＞VPD＞H_r＞C_a＞T_a.Correlation analysis between the some photosynthetic parameters of the upper leaves at flower bud stage and the yield,main agronomy characters and quality characters of seeds showed that photosynthetic parameters were significant correlated with flower yield per plant,100-seed yield and the diameter of top fruit ball and the content of oil.