Irrigation uniformity and wind drift and evaporation losses (WDEL) are major concerns for the design and management of sprinkler irrigation systems under arid or semi-arid conditions. Field trials were carried out to ...Irrigation uniformity and wind drift and evaporation losses (WDEL) are major concerns for the design and management of sprinkler irrigation systems under arid or semi-arid conditions. Field trials were carried out to assess irrigation uniformity and WDEL under various wind velocities, sprinkler spacings and operating pressure heads. Based on experimental data, a frequency analysis was performed to infer the occurrence probability of a given uniformity coefficient (UC). In addition, statistical regressions were used to model WDEL as a function of different climatic variables. Increasing the operating pressure head improved uniformity at low wind speeds. It was shown that UC has been severely impaired at wind speeds above 4 m/s. In the prevailing wind conditions, the frequency analysis showed that a sprinkler spacing of 12 m × 12 m provided the best uniformity. In the local conditions, it is recommended to stop irrigation when wind velocity exceeds 4 m/s. Moreover, it was shown that wind speed and relative humidity were the main significant variables influencing WDEL.展开更多
Objective:To assess the chemical components and toxicity of Artemisia herba-alba(A.herba-alba)essential oil against two major stored cereal pests,Tribolium castaneum(T.castaneum)and Trogoderma granarium(T.granarium).M...Objective:To assess the chemical components and toxicity of Artemisia herba-alba(A.herba-alba)essential oil against two major stored cereal pests,Tribolium castaneum(T.castaneum)and Trogoderma granarium(T.granarium).Methods:Two bioassay actions were tasted:repellent and fumigant actions against adult and larvae,respectively,to assess the effect of A.herba-alba essential oil.Results:Gas chromatography-mass spectrometer analyses of the essential oil contained β-thujone(12.50%),α-thujone(8.78%),sabinyl acetate(8.56%),terpinene-4-ol(8.51%),α-terpineol(3.35%),1,8-cineol(5.45%),γ-terpene(4.82%),camphor(4.52%),dimethylethylbenzene(3.93%)and α-terpinene(3.35%)as the major components.Fumigant toxicity tests showed that A.herba-alba oil was more toxic than T.granarium(LC_(50)=2.09 mg/mL,LC_(90)=4.12 mg/mL)and T.castaneum(LC_(50)=6.39 mg/mL,LC_(90)=10.10 mg/mL).Conclusions:This study has highlighted a bioinsecticide activity of A.herba-alba against two insect pests of stored foodstuffs(T.castaneum and T.granarium).The Artemisia essential oil offers an interesting potential insecticide that could be studied more deeply to isolate and identify the active substances,to study their physiological impact on other insects.展开更多
Objective:To evaluate toxic activities of essential oils obtained from Rosmarinus officinalis and Lavandula stoechas against the fourth larval instars of Orgyia trigotephras.Methods:A total of 1200 larvae were divided...Objective:To evaluate toxic activities of essential oils obtained from Rosmarinus officinalis and Lavandula stoechas against the fourth larval instars of Orgyia trigotephras.Methods:A total of 1200 larvae were divided into three groups-I,II,III.Group I was to investigate the effect of extracted essential oils from these aromatic plants as gastric disturbance.Bacillus thuringiensis was used as referencee and ethanol as control.Group II was used as contact action and Group III was used as fumigant action.For both Groups II and III,Decis was used as reference and ethanol as control.During the three experiments,the effect of essential oils on larvae was assessed.Results:The chemical composition of essential oils from two medicinal plants was determined,and their insecticidal effects on the fourth larval state of Orgyia trigotephras were assessed.They presented an insecticidal activity.Rosmarinus officinalis essential oil was less efficient compared to Lavandula stoechas.Conclusions:The relationship between the chemical composition and the biological activities is confirmed by the present findings.Therefore the potential uses of these essential oils as bioinsecticides can be considered as an alternative to the use of synthetic products.展开更多
文摘Irrigation uniformity and wind drift and evaporation losses (WDEL) are major concerns for the design and management of sprinkler irrigation systems under arid or semi-arid conditions. Field trials were carried out to assess irrigation uniformity and WDEL under various wind velocities, sprinkler spacings and operating pressure heads. Based on experimental data, a frequency analysis was performed to infer the occurrence probability of a given uniformity coefficient (UC). In addition, statistical regressions were used to model WDEL as a function of different climatic variables. Increasing the operating pressure head improved uniformity at low wind speeds. It was shown that UC has been severely impaired at wind speeds above 4 m/s. In the prevailing wind conditions, the frequency analysis showed that a sprinkler spacing of 12 m × 12 m provided the best uniformity. In the local conditions, it is recommended to stop irrigation when wind velocity exceeds 4 m/s. Moreover, it was shown that wind speed and relative humidity were the main significant variables influencing WDEL.
文摘Objective:To assess the chemical components and toxicity of Artemisia herba-alba(A.herba-alba)essential oil against two major stored cereal pests,Tribolium castaneum(T.castaneum)and Trogoderma granarium(T.granarium).Methods:Two bioassay actions were tasted:repellent and fumigant actions against adult and larvae,respectively,to assess the effect of A.herba-alba essential oil.Results:Gas chromatography-mass spectrometer analyses of the essential oil contained β-thujone(12.50%),α-thujone(8.78%),sabinyl acetate(8.56%),terpinene-4-ol(8.51%),α-terpineol(3.35%),1,8-cineol(5.45%),γ-terpene(4.82%),camphor(4.52%),dimethylethylbenzene(3.93%)and α-terpinene(3.35%)as the major components.Fumigant toxicity tests showed that A.herba-alba oil was more toxic than T.granarium(LC_(50)=2.09 mg/mL,LC_(90)=4.12 mg/mL)and T.castaneum(LC_(50)=6.39 mg/mL,LC_(90)=10.10 mg/mL).Conclusions:This study has highlighted a bioinsecticide activity of A.herba-alba against two insect pests of stored foodstuffs(T.castaneum and T.granarium).The Artemisia essential oil offers an interesting potential insecticide that could be studied more deeply to isolate and identify the active substances,to study their physiological impact on other insects.
文摘Objective:To evaluate toxic activities of essential oils obtained from Rosmarinus officinalis and Lavandula stoechas against the fourth larval instars of Orgyia trigotephras.Methods:A total of 1200 larvae were divided into three groups-I,II,III.Group I was to investigate the effect of extracted essential oils from these aromatic plants as gastric disturbance.Bacillus thuringiensis was used as referencee and ethanol as control.Group II was used as contact action and Group III was used as fumigant action.For both Groups II and III,Decis was used as reference and ethanol as control.During the three experiments,the effect of essential oils on larvae was assessed.Results:The chemical composition of essential oils from two medicinal plants was determined,and their insecticidal effects on the fourth larval state of Orgyia trigotephras were assessed.They presented an insecticidal activity.Rosmarinus officinalis essential oil was less efficient compared to Lavandula stoechas.Conclusions:The relationship between the chemical composition and the biological activities is confirmed by the present findings.Therefore the potential uses of these essential oils as bioinsecticides can be considered as an alternative to the use of synthetic products.
