There is limited information about the combined effect of shading time and nitrogen (N) on grain filling and quality of rice. Therefore, two japonica super rice cultivars, Nanjing 44 and Ningjing 3, were used to stu...There is limited information about the combined effect of shading time and nitrogen (N) on grain filling and quality of rice. Therefore, two japonica super rice cultivars, Nanjing 44 and Ningjing 3, were used to study the effect of shading time and N level on the characteristics of rice panicle and grain filling as well as the corresponding yield and quality. At a low N level (150 kg N ha^-1, 150N), grain yield decreased (by 21.07-26.07%) under the treatment of 20 days of shading before heading (BH) compared with the no shading (NS) treatment. These decreases occurred because of shortened panicle length, decreased number of primary and secondary branches, as well as the grain number and weight per panicle. At 150N, in the treatment of 20 days of shading after heading (AH), grain yield also decreased (by 9.46-10.60%) due to the lower grain weight per panicle. The interaction of shading and N level had a significant effect on the number of primary and secondary branches. A high level of N (300 kg N ha^-1, 300N) could offset the negative effect of shading on the number of secondary branches and grain weight per panicle, and consequently increased the grain yield in both shading treatments. In superior grains, compared with 150N NS, the time to reach 99% of the grain weight (T99) was shortened by 1.6 to 1.7 days, and the grain weight was decreased by 4.18-5.91% in 150N BH. In 150N AH, the grain weight was 13.39-13.92% lower than that in 150N NS due to the slow mean and the maximum grain-filling rate (GRmean and GRmax). In inferior grains, grain weight and GRmean had a tendency of 150N NS〉150N BH〉150N AH. Under shaded conditions, 300N decreased the grain weight due to lower GReen both in superior and inferior grains. Compared with 150N NS, the milling and appearance qualities as well as eating and cooking quality were all decreased in 150N BH and 150N AH. Shading with the high level of 300N improved the milling quality and decreased the number of chalky rice kernels, but the eating and cooking quality was reduced with increased chalky area and overall chalkiness. Therefore, in the case of short term shading, appropriate N fertilizer could be used to improve the yield and milling quality of rice, but limited application of N fertilizer is recommended to achieve good eating and cooking quality of rice.展开更多
Litter decomposition is the fundamental process in nutrient cycling and soil carbon(C) sequestration in terrestrial ecosystems. The global-wide increase in nitrogen(N) inputs is expected to alter litter decomposit...Litter decomposition is the fundamental process in nutrient cycling and soil carbon(C) sequestration in terrestrial ecosystems. The global-wide increase in nitrogen(N) inputs is expected to alter litter decomposition and,ultimately, affect ecosystem C storage and nutrient status. Temperate grassland ecosystems in China are usually N-deficient and particularly sensitive to the changes in exogenous N additions. In this paper, we conducted a 1,200-day in situ experiment in a typical semi-arid temperate steppe in Inner Mongolia to investigate the litter decomposition as well as the dynamics of litter C and N concentrations under three N addition levels(low N with 50 kg N/(hm2?a)(LN), medium N with 100 kg N/(hm2?a)(MN), and high N with 200 kg N/(hm2?a)(HN)) and three N addition forms(ammonium-N-based with 100 kg N/(hm2?a) as ammonium sulfate(AS), nitrate-N-based with 100 kg N/(hm2?a) as sodium nitrate(SN), and mixed-N-based with 100 kg N/(hm2?a) as calcium ammonium nitrate(CAN)) compared to control with no N addition(CK). The results indicated that the litter mass remaining in all N treatments exhibited a similar decomposition pattern: fast decomposition within the initial 120 days, followed by a relatively slow decomposition in the remaining observation period(120–1,200 days). The decomposition pattern in each treatment was fitted well in two split-phase models, namely, a single exponential decay model in phase I(〈398 days) and a linear decay function in phase II(≥398 days). The three N addition levels exerted insignificant effects on litter decomposition in the early stages(〈398 days, phase I; P〉0.05). However, MN and HN treatments inhibited litter mass loss after 398 and 746 days, respectively(P〈0.05). AS and SN treatments exerted similar effects on litter mass remaining during the entire decomposition period(P〉0.05). The effects of these two N addition forms differed greatly from those of CAN after 746 and 1,053 days, respectively(P〈0.05). During the decomposition period, N concentrations in the decomposing litter increased whereas C concentrations decreased, which also led to an exponential decrease in litter C:N ratios in all treatments. No significant effects were induced by N addition levels and forms on litter C and N concentrations(P〉0.05). Our results indicated that exogenous N additions could exhibit neutral or inhibitory effects on litter decomposition, and the inhibitory effects of N additions on litter decomposition in the final decay stages are not caused by the changes in the chemical qualities of the litter, such as endogenous N and C concentrations. These results will provide an important data basis for the simulation and prediction of C cycle processes in future N-deposition scenarios.展开更多
In this study,effects of nitrogen( N) amount applied on photosynthesis behaviors of the summer millet in North China was investigated. Photosynthetic rates( Pn),chlorophyll contents( Chl),photosynthetic active d...In this study,effects of nitrogen( N) amount applied on photosynthesis behaviors of the summer millet in North China was investigated. Photosynthetic rates( Pn),chlorophyll contents( Chl),photosynthetic active duration( PAD),and chlorophyll relative steady phase( RSP) in flag and the upper third leaves were assessed in cultivars of Baogu 19,Jigu 19,9050,and 60 D under three N treatments [i. e.,0( control),75,and 150 kg/hm2]. Results indicated that the photosynthesis parameters were drastically regulated by external N levels,all of them showing elevation along with the increased N input in both assayed leaves.Among the cultivars examined,behaviors of the photosynthetic parameters were much better in Baogu 19 and worse in 60 D. The plant yields in the cultivars under various N treatments were shown to be in consistent with the behavior of the photosynthesis parameters. Correlation analysis revealed that plant yield is positively correlated with Pn and Chl and significantly positively correlated with PAD and RSP,suggesting that longer effective photosynthetic duration of leaves impacts largely on plant biomass production and the yield formation potential. Our investigation indicates that suitable external N applied can increase the yield of summer millet associating with the improvement of photosynthesis behaviors in upper leaves that contribute to plant biomass at the late growth stage. Baogu 19 exhibited higher plant yield together with improved photosynthetic parameters in upper leaves,suggesting its potential as an elite cultivar in planting in the summer season of North China.展开更多
To investigate the food web structure of Liusha Bay,the δ13C and δ15N values of various organisms collected in Liusha Bay were measured via stable isotope technique.Based on the calculated δ15N value,the correlatio...To investigate the food web structure of Liusha Bay,the δ13C and δ15N values of various organisms collected in Liusha Bay were measured via stable isotope technique.Based on the calculated δ15N value,the correlation between stable isotope ratio and trophic level were established to predict the trophic levels of shrimps,crabs,cephalopods and fishes.By comparing the analysis results of stomach contents of 24 organisms,two methods gave a similar consistence in approximately 71% of organisms within a 0.5 trophic level.It is concluded that stable isotope technique could be an effective method for studying ocean food web trophic level.展开更多
We focus on the elliptic genera of level N at the cusps of a congruence subgroup for any complete intersection.Writing the first Chern class of a complete intersection as a product of an integral coefficient c1 and a ...We focus on the elliptic genera of level N at the cusps of a congruence subgroup for any complete intersection.Writing the first Chern class of a complete intersection as a product of an integral coefficient c1 and a generator of the 2nd integral cohomology group,we mainly discuss the values of the elliptic genera of level N for the complete intersection in the cases of c_(1)>,=,or<0.In particular,the values about the Todd genus,Â-genus,and A_(k)-genus can be derived from the elliptic genera of level N.展开更多
基金grants from the National Key Technology R&D Program of China (2016YFD0300503)the Key Research Program of Jiangsu Province, China (BE2016344)+3 种基金the earmarked fund for China Agriculture Research System (CARS-01-27)the National Nature Science Foundation of China (31701350)the Program for Scientific Elitists of Yangzhou University, Chinafunded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘There is limited information about the combined effect of shading time and nitrogen (N) on grain filling and quality of rice. Therefore, two japonica super rice cultivars, Nanjing 44 and Ningjing 3, were used to study the effect of shading time and N level on the characteristics of rice panicle and grain filling as well as the corresponding yield and quality. At a low N level (150 kg N ha^-1, 150N), grain yield decreased (by 21.07-26.07%) under the treatment of 20 days of shading before heading (BH) compared with the no shading (NS) treatment. These decreases occurred because of shortened panicle length, decreased number of primary and secondary branches, as well as the grain number and weight per panicle. At 150N, in the treatment of 20 days of shading after heading (AH), grain yield also decreased (by 9.46-10.60%) due to the lower grain weight per panicle. The interaction of shading and N level had a significant effect on the number of primary and secondary branches. A high level of N (300 kg N ha^-1, 300N) could offset the negative effect of shading on the number of secondary branches and grain weight per panicle, and consequently increased the grain yield in both shading treatments. In superior grains, compared with 150N NS, the time to reach 99% of the grain weight (T99) was shortened by 1.6 to 1.7 days, and the grain weight was decreased by 4.18-5.91% in 150N BH. In 150N AH, the grain weight was 13.39-13.92% lower than that in 150N NS due to the slow mean and the maximum grain-filling rate (GRmean and GRmax). In inferior grains, grain weight and GRmean had a tendency of 150N NS〉150N BH〉150N AH. Under shaded conditions, 300N decreased the grain weight due to lower GReen both in superior and inferior grains. Compared with 150N NS, the milling and appearance qualities as well as eating and cooking quality were all decreased in 150N BH and 150N AH. Shading with the high level of 300N improved the milling quality and decreased the number of chalky rice kernels, but the eating and cooking quality was reduced with increased chalky area and overall chalkiness. Therefore, in the case of short term shading, appropriate N fertilizer could be used to improve the yield and milling quality of rice, but limited application of N fertilizer is recommended to achieve good eating and cooking quality of rice.
基金funded by the National Natural Science Foundation of China (41073061, 41203054, 40730105, 40973057)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-302)
文摘Litter decomposition is the fundamental process in nutrient cycling and soil carbon(C) sequestration in terrestrial ecosystems. The global-wide increase in nitrogen(N) inputs is expected to alter litter decomposition and,ultimately, affect ecosystem C storage and nutrient status. Temperate grassland ecosystems in China are usually N-deficient and particularly sensitive to the changes in exogenous N additions. In this paper, we conducted a 1,200-day in situ experiment in a typical semi-arid temperate steppe in Inner Mongolia to investigate the litter decomposition as well as the dynamics of litter C and N concentrations under three N addition levels(low N with 50 kg N/(hm2?a)(LN), medium N with 100 kg N/(hm2?a)(MN), and high N with 200 kg N/(hm2?a)(HN)) and three N addition forms(ammonium-N-based with 100 kg N/(hm2?a) as ammonium sulfate(AS), nitrate-N-based with 100 kg N/(hm2?a) as sodium nitrate(SN), and mixed-N-based with 100 kg N/(hm2?a) as calcium ammonium nitrate(CAN)) compared to control with no N addition(CK). The results indicated that the litter mass remaining in all N treatments exhibited a similar decomposition pattern: fast decomposition within the initial 120 days, followed by a relatively slow decomposition in the remaining observation period(120–1,200 days). The decomposition pattern in each treatment was fitted well in two split-phase models, namely, a single exponential decay model in phase I(〈398 days) and a linear decay function in phase II(≥398 days). The three N addition levels exerted insignificant effects on litter decomposition in the early stages(〈398 days, phase I; P〉0.05). However, MN and HN treatments inhibited litter mass loss after 398 and 746 days, respectively(P〈0.05). AS and SN treatments exerted similar effects on litter mass remaining during the entire decomposition period(P〉0.05). The effects of these two N addition forms differed greatly from those of CAN after 746 and 1,053 days, respectively(P〈0.05). During the decomposition period, N concentrations in the decomposing litter increased whereas C concentrations decreased, which also led to an exponential decrease in litter C:N ratios in all treatments. No significant effects were induced by N addition levels and forms on litter C and N concentrations(P〉0.05). Our results indicated that exogenous N additions could exhibit neutral or inhibitory effects on litter decomposition, and the inhibitory effects of N additions on litter decomposition in the final decay stages are not caused by the changes in the chemical qualities of the litter, such as endogenous N and C concentrations. These results will provide an important data basis for the simulation and prediction of C cycle processes in future N-deposition scenarios.
基金Supported by Special Fund for Agricultural Science and Technology Achievement Transformation in Hebei Province(17826335D)National Millet and Sorghum Industry Technology System"Baoding Comprehensive Experimental Station"(CARS-06-13.5-B2)
文摘In this study,effects of nitrogen( N) amount applied on photosynthesis behaviors of the summer millet in North China was investigated. Photosynthetic rates( Pn),chlorophyll contents( Chl),photosynthetic active duration( PAD),and chlorophyll relative steady phase( RSP) in flag and the upper third leaves were assessed in cultivars of Baogu 19,Jigu 19,9050,and 60 D under three N treatments [i. e.,0( control),75,and 150 kg/hm2]. Results indicated that the photosynthesis parameters were drastically regulated by external N levels,all of them showing elevation along with the increased N input in both assayed leaves.Among the cultivars examined,behaviors of the photosynthetic parameters were much better in Baogu 19 and worse in 60 D. The plant yields in the cultivars under various N treatments were shown to be in consistent with the behavior of the photosynthesis parameters. Correlation analysis revealed that plant yield is positively correlated with Pn and Chl and significantly positively correlated with PAD and RSP,suggesting that longer effective photosynthetic duration of leaves impacts largely on plant biomass production and the yield formation potential. Our investigation indicates that suitable external N applied can increase the yield of summer millet associating with the improvement of photosynthesis behaviors in upper leaves that contribute to plant biomass at the late growth stage. Baogu 19 exhibited higher plant yield together with improved photosynthetic parameters in upper leaves,suggesting its potential as an elite cultivar in planting in the summer season of North China.
基金Supported by Public Science and Technology Research Funds Projects of Ocean(200905005-05)Special S&T Program for Key Independent Innovation in Guangdong Province(2007A032600004)
文摘To investigate the food web structure of Liusha Bay,the δ13C and δ15N values of various organisms collected in Liusha Bay were measured via stable isotope technique.Based on the calculated δ15N value,the correlation between stable isotope ratio and trophic level were established to predict the trophic levels of shrimps,crabs,cephalopods and fishes.By comparing the analysis results of stomach contents of 24 organisms,two methods gave a similar consistence in approximately 71% of organisms within a 0.5 trophic level.It is concluded that stable isotope technique could be an effective method for studying ocean food web trophic level.
基金the Natural Science Foundation of Tianjin City of China(Grant No.19JCY-BJC30300)the National Natural Science Foundation of China(Grant No.12071337).
文摘We focus on the elliptic genera of level N at the cusps of a congruence subgroup for any complete intersection.Writing the first Chern class of a complete intersection as a product of an integral coefficient c1 and a generator of the 2nd integral cohomology group,we mainly discuss the values of the elliptic genera of level N for the complete intersection in the cases of c_(1)>,=,or<0.In particular,the values about the Todd genus,Â-genus,and A_(k)-genus can be derived from the elliptic genera of level N.