Volatile components of Rhizoma Alpiniae Officinarum using three different extraction methods combined with gas chromatography-mass spectrometry

Volatile components from Rhizoma Alpiniae Officinarum were respectively extracted by three methods including hydrodistillation, headspace solid-phase microextraction （HS-SPME） and diethyl ether extraction. A total of 40 （hydrodistillation）, 32 （HS-SPME） and 37 （diethyl ether extraction） compounds were respectively identified by gas chromatography-mass spectrometry （GC/MS） and 22 compounds were overlapped, including β-farnesene, 7-muurolene, 2,6-dimethyl-6- （4-methyl-3-pentenyl）bicyclo[3.1.1]hept-2-ene, eucalyptol and cadina-1（10）, 4-diene and so forth, varying in relative contents. HS-SPME is fast, sample saving and solvent-free and it also can achieve similar profiles as those from hydrodistillation and solvent extraction. Therefore, it can be the priority for extracting volatile components from medicinal plants.

Effects of Different Irrigation Modes on Internal Quality of Flue-cured Tobacco Leaves

[Objective] This study aimed to investigate the effects of different irrigation modes on chemical constituent and aroma substance contents and sensory quality in flue-cured tobacco leaves. [Method] Field experiments were conduced with two treatments, including watering irrigation and micro-spraying irrigation. In watering irrigation treatment, flue-cured tobacco seedlings were respectively watered by artificial root irrigation once at rosette stage（May 26） and vigorous growth stage（June 18）, 1kg/plant each time; in micro-spraying treatment, flue-cured tobacco seedlings were watered by artificial root irrigation once at rosette stage（May 26）, 1 L/plant. [Result]Compared to watering irrigation mode, micro-spraying irrigation could extremely significantly increase the content of main aromatic substance in middle and upper leaves.Contents of main aromatic substance non-volatile organic acids, volatile organic acids, petroleum ether extracts, neophytadiene and neutral aromatic substances in C3F tobacco leaves were improved by 24.4%, 32.6%, 20.7%, 33.8% and 26.3%, respectively; contents of main aromatic substance non-volatile organic acids, volatile organic acids, petroleum ether extracts, eophytadiene and neutral aromatic substances in B2F tobacco leaves were improved by 16.3%, 6.0%, 6.1%, 10.8% and8.1%, respectively. In addition, micro-spraying irrigation could extremely significantly reduce the nicotine content in middle and upper leaves and improve the aromatic coordination, mellow taste and smoldering property. [Conclusion] In flue-cured tobacco production, micro-spraying technology is an important means to improve the internal quality of flue-cured tobacco leaves, which can be adopted to effectively solve the problem of declining quality of flue-cured tobacco leaves resulted from the dry climate at maturation stage in seasonal frequent-drought areas.

Insecticidal Activity of Crude Extracts of Hyptis suaveolens(Bush Mint)on Anopheles Mosquitoes Collected from Lafia,Nasarawa State,Nigeria

Anopheles gambiae is a vector that is responsible for the transmission of malaria parasites which causes high morbidity and mortality in Nigeria and the world at large.Human-vector contact can be reduced by the use of conventional repellents being sold in the market,though some of these repellent are not environmentally friendly and An.gambiae have developed resistance to some of these repellents.To this end,the phytochemical constituents and insecticidal activity of crude extracts of Hyptis suaveolens(bush mint)was determined on adult An.gambiae mosquitoes collected from Lafia,Nasarawa State,Nigeria to evaluate its effect in controlling them.Here,70%ethanolic and diethyl ether fat crude extracts were made from H.suaveolens dried leaves and used to carry out the experiment.The phytochemical screening of the ethanol extract revealed the presence of alkaloids,flavonoid,saponins,tannins,steroids and reducing sugar.Glycoside was not detected in the ethanol extract.Only steroids was detected in diethyl ether extract the rest of the phytochemical tested were absent.An.gambiae larvae were collected from the field and were raised to F1 progeny adults that were used for the study.WHO protocol for carrying out human bait repellency cage test was used.Human hand treated with the extracts was exposed to a cage containing 30 female mosquitoes for each of the extracts respectively.The ethanolic crude extract treatment proved to be more effective in repelling mosquitoes with 0%(0/30)mosquito landing than diethyl ether extract which had 40%(12/30)mosquitoes landing and the control hand(untreated left hand)had the highest landing rate 63.3%(19/30)which showed very high significant difference(χ^(2)=27.2619,df=2,P<0.00001)in relation to the treatments.After 24 hours holding period,the mortality rate of exposed mosquitoes was observed to be highest in the ethanolic treatment 73.3%(22/30).In conclusion,H.suaveolens extracts have repellency potential in controlling adult An.gambiae.

Effect of Long-term Experimental Warming on the Nutritional Quality of Alpine Meadows in the Northern Tibet

The nutritional quality of grasslands is closely related to recruitment of young and population dynamics of livestock and wild herbivores. However, the response of nutritional quality to climate warming has not been fully understood in the alpine meadow on the Tibetan Plateau, especially in the Northern Tibet. Here, we investigated the effect of experimental warming(beginning in 2008) on nutritional quality in three alpine meadows(site A: 4313 m, B: 4513 m and C: 4693 m) in the Northern Tibet. Crude protein(CP), neutral detergent fiber(NDF), acid detergent fiber(ADF), crude ash(Ash), ether extract(EE) and water-soluble carbohydrate(WSC) were examined in 2018–2019. Experimental warming only increased the content of CP by 27.25%, ADF by 89.93% and NDF by 41.20%, but it decreased the content of Ash by 57.76% in 2019 at site B. The contents of CP and WSC both increased with soil moisture(SM). The content of CP decreased with vapor pressure deficit(VPD). The combined effect of SM and VPD was greater than air temperature(Ta) in controlling the variations of the CP content, ADF content and nutritional quality. Compared to Ta, VPD explained more of the variation in NDF and Ash content. All of these findings suggest that warming effects on nutritional quality may vary with site and year, and water availability may have a stronger effect on the nutritional quality than temperature in the alpine meadow of the Northern Tibet.