Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and frag...Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.展开更多
OBJECTIVE This study aimed to optimize polysaccharides extraction from Urena lobata L.and investigate its antioxidant activity.METHODS The mathematical model was established by re.sponse surface method(RSM) based on t...OBJECTIVE This study aimed to optimize polysaccharides extraction from Urena lobata L.and investigate its antioxidant activity.METHODS The mathematical model was established by re.sponse surface method(RSM) based on the results of single factor experiments,using polysaccha.rides extraction rate as response value,and using the ratio of water to material,cellulase concentra.tion,extraction temperature and time as experimental factors,which was used to screen optimum poly.saccharide extraction conditions from Urena lobata L..Antioxidant activity of polysaccharides was stud.ied by DPPH and ·OH free radical elimination method.RESULTS The optimum conditions obtained by RSM were as follows:the cellulase level was 10.8 g·L^(-1),extraction time duration was 72 min,the ra.tio of water to feedstock was 7 mL·g^(-1),extraction temperature was 43℃,the pH value was 5.0.Under the optimal conditions,there was a difference of less than 5% between predicted extraction rate 13.37% and experimental extraction rate 13.32%.The polysaccharide yield was most significantly af.fected by cellulase concentration,followed by extraction time,water to material ratio and extraction tem.perature.IC50 of DPPH and ·OH were 1.082 g·L^(-1) and 3.202 mg·L^(-1),respectively.Antioxidant activity of sample polysaccharides was weaker than those of vitamin C.CONCLUSION The polysaccharide extraction process from Urena lobata L.by cellulase enzymolysis approach was obtained,which was convenient and feasible,and extracted polysaccharides had good free radical scavenging activity.展开更多
基金This project was financially supported by the National Natural Science Foundation of China(31601244 and 31971843)the Guangdong Provincial Key Field Research and Development Plan Project,China(2019B020221003)the Modern Agricultural Industrial Technology System of Guangdong Province,China(2020KJ105).
文摘Fragrant rice has a high market value,and it is a popular rice type among consumers owing to its pleasant flavor.Plantation methods,nitrogen(N)fertilizers,and silicon(Si)fertilizers can affect the grain yield and fragrance of fragrant rice.However,the core commercial rice production attributes,namely the head rice yield(HRY)and 2-acetyl-1-pyrroline(2-AP)content of fragrant rice,under various nitrogen and silicon(N-Si)fertilization levels and different plantation methods remain unknown.The field experiment in this study was performed in the early seasons of 2018 and 2019 with two popular indica fragrant rice cultivars(Yuxiangyouzhan and Xiangyaxiangzhan).They were grown under six N-Si fertilization treatments(combinations of two levels of Si fertilizer,0 kg Si ha^(−1)(Si0)and 150 kg Si ha^(−1)(Si1),and three levels of N fertilizer,0 kg N ha^(−1)(N0),150 kg N ha^(−1)(N1),and 220 kg N ha^(−1)(N2))and three plantation methods(artificial transplanting(AT),mechanical transplanting(MT),and mechanical direct-seeding(MD)).The results showed that the N-Si fertilization treatments and all the plantation methods significantly affected the HRY and 2-AP content and related parameters of the two different fragrant rice cultivars.Compared with the Si0N0 treatment,the N-Si fertilization treatments resulted in higher HRY and 2-AP contents.The rates of brown rice,milled rice,head rice,and chalky rice of the fragrant rice also improved with the N-Si fertilization treatments.The N-Si fertilization treatments increased the activities of N metabolism enzymes and the accumulation of N and Si in various parts of the fragrant rice,and affected their antioxidant response parameters.The key parameters for the HRY and 2-AP content were assessed by redundancy analysis.Furthermore,the structural equation model revealed that the Si and N accumulation levels indirectly affected the HRY by affecting the N metabolism enzyme activity,N use efficiency,and grain quality of fragrant rice.Moreover,high N and Si accumulation directly promoted the 2-AP content or affected the antioxidant response parameters and indirectly regulated 2-AP synthesis.The interactions of the MT method with the N-Si fertilization treatments varied in the fragrant rice cultivars in terms of the HRY and 2-AP content,whereas the MD method was beneficial to the 2-AP content in both fragrant rice cultivars under the N-Si fertilization treatments.
基金The project supported by Natural Science Foundation of Guangxi Zhuang Autonomous Region of China (2016GXNSFBA380040) and Scientific and Technological Research Projects of Yulin City of China (20173104 and 20173102)
文摘OBJECTIVE This study aimed to optimize polysaccharides extraction from Urena lobata L.and investigate its antioxidant activity.METHODS The mathematical model was established by re.sponse surface method(RSM) based on the results of single factor experiments,using polysaccha.rides extraction rate as response value,and using the ratio of water to material,cellulase concentra.tion,extraction temperature and time as experimental factors,which was used to screen optimum poly.saccharide extraction conditions from Urena lobata L..Antioxidant activity of polysaccharides was stud.ied by DPPH and ·OH free radical elimination method.RESULTS The optimum conditions obtained by RSM were as follows:the cellulase level was 10.8 g·L^(-1),extraction time duration was 72 min,the ra.tio of water to feedstock was 7 mL·g^(-1),extraction temperature was 43℃,the pH value was 5.0.Under the optimal conditions,there was a difference of less than 5% between predicted extraction rate 13.37% and experimental extraction rate 13.32%.The polysaccharide yield was most significantly af.fected by cellulase concentration,followed by extraction time,water to material ratio and extraction tem.perature.IC50 of DPPH and ·OH were 1.082 g·L^(-1) and 3.202 mg·L^(-1),respectively.Antioxidant activity of sample polysaccharides was weaker than those of vitamin C.CONCLUSION The polysaccharide extraction process from Urena lobata L.by cellulase enzymolysis approach was obtained,which was convenient and feasible,and extracted polysaccharides had good free radical scavenging activity.
