| Siberian apricot(Prunus sibirica L.)is an excellent woody oil tree in northern China.The kernel oil can be used as raw material for producing health-care products,skin-care products and industrial utilizations,also can be regarded as edible oil after being detoxified.However,the apricot trees were mainly distributed in hilly,barren and sandy areas in China.Most of them were in the wild or semi-wild state.The supply of nutrients to Siberian apricot trees was insufficient,which could affect the oil quality of kernels restricting its industrialization.Kernel characteristics,oil contents and fatty acid compositions were studied in Siberian apricot seed developing for analyzing the rule of oil accumulation.And the correlations between the oil triats and mineral elements in the period of maximum oil accumulation were studied as well.The effects of mineral elements on the characteristics of kernel and oil in the period of maximum oil accumulation were investigated,which may provide a reference for improving the oil quality of Siberian apricot kernel.The results were as follows:(1)The development period of Siberian apricot kernels was approximately 60 days.Variation of kernel length(9.62 mm~12.19 mm),kernel breadth(7.66 mm~10.52 mm),kernel thickness(1.37 mm~5.59 mm)and kernel dry biomass(0.05 g~0.34 g)were significant(P<0.01).The development process could be divided into two stages,including rapid growth stage(3 WAA~5 WAA)and slow growth stage(5 WAA~10 WAA).The accumulation of kernel dry biomass during 3 WAA~5 WAA accounted for 59% of the total accumulation in kernel developing.The slow growth stage,at which the variation of the kernel characteristic was small accounted for 2/3 of the total development period.(2)Oil content increased in pattern of “S”,and the highest oil content was up to 51.6% at 8 WAA.Three representative kernel development stages can be identified: slow oil accumulation stage(3 WAA~4 WAA),rapid oil accumulation stage(4 WAA~8 WAA),and stable oil accumulation stage(8 WAA~10 WAA).Eight long-chain fatty acids that the chain length ranging from 16 to 20 carbons were detected during seed development.The content of oleic acid and lenoleic acid varied significantly(P<0.01)and presented an opposite trend in seed developing.Oleic acid increased from 28.45% to 71.24%,whereas linoleic acid decreased from 58.91% to 23.85%.Siberian apricot methyl esters could meet the specifications in biodiesel standards when seeds were harvested at 8,9 and 10 WAA.(3)The content of P,Mg,Fe and Zn was 0.44 mg/g,2.21 mg/g,0.03 mg/g and 0.05 mg/g,respectively at 8 WAA.The content of Mg was 5 times of that of P,and was 73 times of that of Fe and Zn.There were no significant correlations between kernel shape index and Mg,P,Zn and Fe.The content of Fe showed a positive correlation with PUFA(r=0.829*)and significant negative correlation with Mg(r=-0.949**).The content of Mg showed a negative correlation with PUFA(r=-0.886*)and positive correlations with oil content(r=0.895*)and MUFA(r=0.814*).(4)Under different magnesium concentration treatments,kernel morphology,oil content and fatty acid composition varied at 8 WAA.The maximum dry biomass of kernels was 0.39 g under 1.0 % Mg SO4 treatment,which was significantly higher than CK treatment(0.33 g).The lowest oil content was 52.37% under 0.5% Mg SO4 treatment.The highest oil content(57.19%)and the lowest PUFA content(22.55%)could be obtained by spraying 2.5% Mg SO4.There was no significant difference in MUFA content between 2.5% Mg SO4 treatment(73.13%)and 2.0% Mg SO4 treatment with the maximum value of 73.67%.Foliar spraying of Mg SO4 at a concentration of 2.5% was beneficial to obtain the kernel materials with high oil content and ideal biodiesel property. |
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