Yuyu Li

Harvest time and storage time had significant effects on nutrient quality and Volatile Organic Compounds (VOCs) of alfalfa. The objective of this study was to use headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) to analyze alfalfa at different harvest periods (budding stage, early blooming, full blooming), and storage for 0 d, 90 d, 180 d, 270 d, and 360 d, the dynamic changes in VOCs and nutritional quality. Results indicated that ketones, aldehydes, alcohols and esters were the main volatile components of alfalfa VOCs, accounting for 87.41%, 88.57% and 90.85% of the total volatile components at budding stage, early blooming and full blooming, respectively. VOCs and nutrient quality of alfalfa varied significantly in different harvest periods; delayed harvesting significantly reduced alfalfa aldehydes, alcohols, crude protein (CP), and total digestible nutrients (TDN) and significantly increased ketone, dry matter (DM), acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents (p < 0.05). After Comprehensive consideration ofthe yield, nutritional quality and VOCs of alfalfa, the best harvest time was determined to be the budding stage. The VOCs and nutrient quality of alfalfa were significantly different at different storage durations, and ketones, ADF and NDF were significantly increased and significantly reduced DM, CP and TDN (p < 0.05). Ketone content and neutral detergent fiber (NDF) content had a significant positive correlation, (NDF F = 5.5, p = 0.024). Storage 360 d 2-methylbutyraldehyde (musty), 1-octen-3-one (earthy musty odor) content increased. These may be the key compounds that causes the smell of fresh alfalfa to fade away and a musty smell to emerge.

This study aimed to characterize the fungal diversity and mycotoxin concentrations of native grass hay in various storage periods. In the present study, the native grass hay samples were collected when stored for 0 d (D0 group), 30 d (D30 group), and 150 d (D150 group), respectively. Here, mycotoxin analyses combined with ITS gene sequence were performed to reveal the changes in response to the storage period. There were notable differences in deoxynivalenol and aflatoxin B₁ concentrations among the three groups. Compared to the D150 group, the diversity of the fungal community was higher in the D0 and D30 groups, which indicating the diversity was significantly influenced by the storage period. No significant (p > 0.05) difference was observed among the three groups on the dominant phyla. Interestingly, a significant (p < 0.05) difference was also observed in Chactomella and Aspergillus among the three groups, the abundance of the Chactomella was significantly (p < 0.05) decreased and the abundance of Aspergillus was statistically (p < 0.05) increased in the D150 group. Correlation analysis of the association of fungi with mycotoxin could provide a comprehensive understanding of the structure and function of the fungal community. These results indicated that the good practices of storage are essential for the prevention of mycotoxin. The information contained in the present study is vital for the further development of strategies for hay storage with high quality in the harsh Mongolian Plateau ecosystem.

L. indica L. cv. Mengzao, a medicinal plant of the Ixeris genus, is rich in flavonoids. In order to thoroughly analyze the the distribution and dynamic change of major flavonoids in its various parts from different growth periods, the flavonoids extracted from L. indica L. cv. Mengzao were identified and quantitatively analyzed by ultra-high-performance liquid chromatography mass spectrometer (LC-MS/MS). Results indicated that 15 flavonoids were identified from L. indica L. cv. Mengzao, and rutin, luteolin, luteolin-7-O-glucoside, kaempferol, quercetin, and apigenin are the major flavonoids in L. indica L. cv. Mengzao. In general, the total flavonoids’ content in different parts of L. indica L. cv. Mengzao followed the order flowers > leaves > stems > roots. Flowers and leaves are the main harvesting parts of L. indica L. cv. Mengzao, and the flowering period is the most suitable harvesting period. This study provides valuable information for the development and utilization of L. indica L. cv. Mengzao and determined the best part to harvest and the optimal time for harvesting.