Rapid Assessment Of Seed Vigor Of Brassica Based On Near Infrared Spectroscopy

Brassica whose origin is temperate areas of Asia, the western zone of Europe,the Mediterranean zone is one of375species of Brassicaceae, which has been widelydistributed in the north temperate zone and subtropical regions; There are about40species Brassica plants in the world, and there are15species in China which arecommon in the Yangtze River and the west of the mountain zones of Yellow River.Seed vigor is the germination of seed, the potential of seedling growth, the potentialof stress resistance and production of plants, which is an important indicator of seedquality. Seed of high vigor has obvious advantages of growth and potentialproductivity, and is of great importance to agricultural production. Currently,conventional determination methods of seed vigor have the disadvantages of needingto be pretreated of seeds, time-consuming, complicated operation, and damage toseeds, which greatly limit rapid and non-destructive testing of Brassica seeds.Brassica pekinensis, Brassica juncea, Brassica parachinensis seeds were used asexperimental material in this study, and seeds of artificial accelerated aging,germination potential, germination rate and vigor index were detected, OD values ofseed leachate and EC values were detected, soluble sugar and soluble protein contentwere determined, SOD, POD and CAT antioxidant enzyme activity were detected.The indicators above were analyzed to study the mechanism of seed aging. Nearinfrared spectra (wavelength range350～1800nm) were recorded on Brassica seedsusing FT(Filter Transform Near Infrared Spectrometer), multiplicative scattercorrection (MSC) and standard normal variable transformation (SNV) pretreatmentmethods were utilized, and principal component regression (PCR) and partial leastsquares (PLS) were adopted to model, then the correlation coefficient (R) model, theroot mean square error correction (RMSEC) and root mean square error of crossvalidation (RMSECV) were compared, finally the best model was selected to predictseed vigor. The results are as follows:1、For three vegetable seeds, with longer aging time, germination potential,germination rate and vigor index tended to decrease, when seeds aged0～2d,germination potential and germination rate showed a slight downward trend, but when aged3～5d, they had a greater decline, so these two indicators could responseof the change of seed vigor to a certain extent; when seed was aged1～5d, decline ofvigor index was obvious, so it could better respond of the change to seed vigor.2、OD values and EC values of seed leachate increased with the extension ofaging time. OD values of Brassica pekinensis seeds which were aged0～4d had asimilar increasing rate, but it increased rapidly on the5th day; the increasing rate ofOD values of Brassica juncea seeds leachate which were aged2～5d was greaterthan the rate of0～2d; and the increasing rate of OD values of Brassicaparachinensis seeds leachate which were aged3～5d was greater than which wereaged0～3d. With aging time increasing, EC values of the three seeds leachategradually increased, which rose relatively slower during0～2d, while it rose fasterduring3～5d. With increasing of aging time, seed vigor index gradually decreased,seed leachate OD values and EC values gradually increased, so seed vigor had anegative correlation with these two physiological indicators at0.01level, so theseindicators could response to the change of seed vigor to a certain extent.3、With the extension of aging time, soluble sugar content had a significantdecline trend, soluble sugar content of Brassica pekinensis, Brassica juncea andBrassica parachinensis decreased by56.6%,44.7%,32.3%when aged5d. Thechange of soluble protein content was not obvious. So, the seeds of soluble sugarcontent and vigor index were positively correlated at0.01level.4、With the aging time increasing, antioxidant enzymes SOD, POD and CATactivity of seeds decreased. For Brassica pekinensis seeds, when aged1d SODactivity was significantly lower than the control group, with the growth of the agingtime, SOD activity decreased more significantly, trends of POD and CAT activitywere the same with SOD, and had a greater degree of decline. Brassica juncea seedswhen aged1～2d, SOD and CAT activity decreased to a lesser extent, the longer theaging time, the greater the decline, when aged5d, the two decreased30.71%,39.69%respectively, and POD activity declined significantly, when time was2d and5d, these declined by16.62%and48.04%respectively. Compared with the controlgroup, Brassica parachinensis seeds aged1～3d, SOD activity showed a slightdownward trend, the trend become larger during4～5d, and decreased by18.52%, 52.03%respectively; when aged1d, POD and CAT activity were significantlydecreased, when aged5d, these decreased by69.61%,29.77%respectively.5、The results showed that near-infrared spectroscopy and chemometrics methodwas a quick and nondestructive detecting method to detect Brassica seed vigor. First,using near-infrared spectroscopy collected signals of seed surface, and established themodel by principal component regression, research had shown that Brassicapekinensis validation set prediction model established by SNV pretreatment, R,RMSECV and RMSEC were0.979,0.527and0.360; Brassica juncea validation setprediction model established by no pretreatment, R, RMSECV and RMSEC were0.959,0.637and0.482; Brassica parachinensis validation set prediction modelestablished by no pretreatment, R, RMSECV and RMSEC were0.959,0.637and0.482.