Evaluation of growth characteristics of Aspergillus parasiticus inoculated in different culture media by shortwave infrared(SWIR) hyperspectral imaging

The growth characteristics of Aspergillus parasitic us incubated on two culture media were ex-amined using shortwave infrared(SWIR,1000-2500 nm)hyperspectral imaging(HSI)in this work.HSI images of the A.parasiticus colonies growing on rose bengal medium(RBM)and maize agar medium(MAM)were recorded daily for 6 days.The growth phases of A.parasiticus were indicated through the pixel number and average spectra of colonies.On score plot of the first principal component(PC1)and PC2,four growth zones with varying mycelium densities were identified.Eight characteristic wavelengths(1095,1145,1195,1279,1442,1655,1834 and 1929 nm)were selected from PC1 loading,average spectra of each colony as well as each growth zone.F urthermore,support vector machine(S VM)classifier based on the eight wavelengths was built,and the classification accuracies for the four zones(from outer to inner zones)on the colonies on RBM were 99.77%,9935%,99.75%and 99.60%and 99.77%,9939%,99.31%and 98.22%for colonies on MAM.In addition,a new score plot of PC2 and PC3 was used to differ-entiate the colonies incubated on RBM and MAM for 6 days.Then characteristic wavelengths of 1067,1195,1279,1369,1459,1694,1834 and 1929 nm were selected from the loading of PC2 and PCg.Based on them,a new SVM model was developed to diferentiate colonies on RBM and MAM with accuracy of 100.00%and 9999%,respectively.In conclusion,SWIR hyperspectral image is a powerful tool for evaluation of growth characteristics of A.parasiticus incubated in diferent culture media.

Challenges in bermudagrass production in the southeastern USA

Bermudagrass(Cynodon dactylon(L.)Pers.)is one of the primary perennial forages in the southeastern USA.Newer hybrid cultivars have superior production and nutritive value compared to common ecotypes.However,there are many challenges facing bermudagrass production in the region.First,the bermudagrass stem maggot(BSM;Atherigona reversura Villeneuve)has severely damaged bermudagrass throughout the region.Strategically timed pyrethroid applications significantly reduce adult BSM populations,but efforts are needed to develop integrated pest management plans.Second,an increasing number of producers are noting challenges with green-up following winter dormancy.This may be attributed to disease,unbalanced soil fertility,and weed pressure.Perhaps one of the most limiting factors for continued production is the deficit of sprigs and trained personnel to sprig hybrid bermudagrasses.This research is critically important as the need for cold-tolerant bermudagrass is increasing as tall fescue(Lolium arundinaceum(Schreb.)S.J.Darbyshire)is declining due to changes in temperature and precipitation throughout the northern parts of the region.Plant breeders are investigating hybrid bermudagrass at latitudes>35°with respect to freeze or cold tolerance.Despite the many challenges facing hybrid bermudagrass in the southeastern USA,researchers are working to ensure its persistence,productivity,and availability for the future.