以旱稻田间试验资料为基础,对水稻生长模拟模型ORY ZA 2000模拟旱稻生长进行参数校正和验证,图解和回归分析结果显示ORY ZA 2000模拟旱稻生物量、产量、作物吸氮量的模拟值与观测值基本呈线性关系,模拟效果良好,但对土壤水分的模拟效果...以旱稻田间试验资料为基础,对水稻生长模拟模型ORY ZA 2000模拟旱稻生长进行参数校正和验证,图解和回归分析结果显示ORY ZA 2000模拟旱稻生物量、产量、作物吸氮量的模拟值与观测值基本呈线性关系,模拟效果良好,但对土壤水分的模拟效果欠佳,需做进一步研究。应用校正和验证的结果,结合肥料效应函数原理,对旱稻不同灌溉方式和密度管理下的氮肥经济最佳施肥量做了探讨,初步得出了该地区旱稻栽培氮肥经济最佳施肥量,丰富了作物模拟和节水农业的理论和实践,对以后旱稻发展及栽培管理有一定的参考价值。展开更多
Aerobic rice is a new production system in which specially-developed varieties are grown under non-flooded, non-puddled, and non-saturated soil conditions. In 2003-2004, irrigation x Nitrogen experiments were carried ...Aerobic rice is a new production system in which specially-developed varieties are grown under non-flooded, non-puddled, and non-saturated soil conditions. In 2003-2004, irrigation x Nitrogen experiments were carried out near Beijing using variety HD297. Water treatments included four irrigation levels, and Nitrogen treatments included different fertilizer N application rates and different numbers of N splits. The highest yields were 4460 kg/ha with 688 mm of total （rain plus irrigation） water input in 2003 and 6 026 kg/ha with 705 mm of water input in 2004. Because of the quite even distribution of rainfall in both years, the four irrigation treatments did not result in large differences of soil water conditions. There were few significant effects of irrigation on biomass accumulation, but yield increased with the total amount of water applied. High yields coincided with high harvest index and high percentages of grain filling. The application of fertilizer N either reduced biomass and yield or kept it at the same level as 0 N and consistently reduced the percentage grain filling and 1 000-grain weight. With the highest water application, five splits of N gave higher yield than three splits, whereas three splits gave higher yield than five splits with lower water applications.展开更多
Aerobic rice has been considered a promising rice cultivation system as water scarcity is increasing in the world. This article summarizes the advances in aerobic rice management researches in the North China Plain, f...Aerobic rice has been considered a promising rice cultivation system as water scarcity is increasing in the world. This article summarizes the advances in aerobic rice management researches in the North China Plain, focusing on yield formation and its bottleneck. High-yielding and good-quality aerobic rice varieties adapted to aerobic soil conditions have been released officially and adopted by farmers in North China. The varieties Handao 502 and Handao 297 have been recognized as the most promising varieties reaching a yield level ranging 3.5-5.0 t ha-1 with 450-650 mm water input. Compared with lowland rice, water input in aerobic rice was more than 50% lower, and water productivity was 60% higher. Researches on responses of rice cultivars to nitrate nitrogen （N） and ammonium N supplied at early growth stages provided the first evidence for a preference of aerobic rice HD297 for nitrate N supply, compared with the lowland rice variety. Zinc uptake studies demonstrated that introduction of aerobic rice system on calcareous soils may increase zinc deficiency problems. Sink size was identified as the limitation of aerobic rice yield, because its spikelet number m-2 was too low （20000-24 000） compared with the lowland rice. For future research, more attention is suggested to be paid to yield formation focusing on effects of water regimes on tiller dynamics. Understanding of nutrient uptake and response to fertilization effects are also urgently required to establish optimized crop management technology. Additionally, alternative cropping systems based on aerobic rice should be established, and key sustainability and environmental impact issues in the systems need to be identified.展开更多
AIM: To improve the interpretation of fecal immunochemical test (FIT) results in colorectal cancer (CRC) cases from screening and referral cohorts. METHODS: In this comparative observational study, two prospective coh...AIM: To improve the interpretation of fecal immunochemical test (FIT) results in colorectal cancer (CRC) cases from screening and referral cohorts. METHODS: In this comparative observational study, two prospective cohorts of CRC cases were compared. The first cohort was obtained from 10 322 average risk subjects invited for CRC screening with FIT, of which, only subjects with a positive FIT were referred for colonoscopy. The second cohort was obtained from 3637 subjects scheduled for elective colonoscopy with a positive FIT result. The same FIT and positivity threshold (OC sensor; ≥ 50 ng/mL) was used in both cohorts. Colonoscopy was performed in all referral subjects and in FIT positive screening subjects. All CRC cases were selected from both cohorts. Outcome measurements were mean FIT results and FIT scores per tissue tumor stage (T stage). RESULTS: One hundred and eighteen patients with CRC were included in the present study: 28 cases obtained from the screening cohort (64% male; mean age 65 years, SD 6.5) and 90 cases obtained from the referral cohort (58% male; mean age 69 years, SD 9.8). The mean FIT results found were higher in the referral cohort (829 ± 302 ng/mLvs 613 ± 368 ng/mL,P = 0.02). Tissue tumor stage (T stage) distribution was dif-ferent between both populations [screening population: 13 (46%) T1, eight (29%) T2, six (21%) T3, one (4%) T4 carcinoma; referral population: 12 (13%) T1, 22 (24%) T2, 52 (58%) T3, four (4%) T4 carcinoma], and higher T stage was significantly associated with higher FIT results (P < 0.001). Per tumor stage, no significant difference in mean FIT results was observed (screening vs referral: T1 498 ± 382 ng/mL vs 725 ± 374 ng/mL, P = 0.22; T2 787 ± 303 ng/mL vs 794 ± 341 ng/mL, P = 0.79; T3 563 ± 368 ng/mLvs 870 ± 258 ng/mL,P = 0.13; T4 not available). After correction for T stage in logistic regression analysis, no significant differences in mean FIT results were observed between both types of cohorts (P = 0.10). CONCLUSION: Differences in T stage distribution 展开更多
文摘以旱稻田间试验资料为基础,对水稻生长模拟模型ORY ZA 2000模拟旱稻生长进行参数校正和验证,图解和回归分析结果显示ORY ZA 2000模拟旱稻生物量、产量、作物吸氮量的模拟值与观测值基本呈线性关系,模拟效果良好,但对土壤水分的模拟效果欠佳,需做进一步研究。应用校正和验证的结果,结合肥料效应函数原理,对旱稻不同灌溉方式和密度管理下的氮肥经济最佳施肥量做了探讨,初步得出了该地区旱稻栽培氮肥经济最佳施肥量,丰富了作物模拟和节水农业的理论和实践,对以后旱稻发展及栽培管理有一定的参考价值。
基金Supported by the CGIAR Challenge Program on Water and Food through the project "Developing a System of Temperate and Tropical Aerobic Rice in Asia (STAR)", the Swiss Agency for Development and Cooperation (SDC) through the water workgroup of the Irrigated Rice Research Consortium (IRRC)the Chinese Government through the "863" project of "2006AA100203-04" and the "948" project of "2006-G52A-Q08".
文摘Aerobic rice is a new production system in which specially-developed varieties are grown under non-flooded, non-puddled, and non-saturated soil conditions. In 2003-2004, irrigation x Nitrogen experiments were carried out near Beijing using variety HD297. Water treatments included four irrigation levels, and Nitrogen treatments included different fertilizer N application rates and different numbers of N splits. The highest yields were 4460 kg/ha with 688 mm of total （rain plus irrigation） water input in 2003 and 6 026 kg/ha with 705 mm of water input in 2004. Because of the quite even distribution of rainfall in both years, the four irrigation treatments did not result in large differences of soil water conditions. There were few significant effects of irrigation on biomass accumulation, but yield increased with the total amount of water applied. High yields coincided with high harvest index and high percentages of grain filling. The application of fertilizer N either reduced biomass and yield or kept it at the same level as 0 N and consistently reduced the percentage grain filling and 1 000-grain weight. With the highest water application, five splits of N gave higher yield than three splits, whereas three splits gave higher yield than five splits with lower water applications.
文摘Aerobic rice has been considered a promising rice cultivation system as water scarcity is increasing in the world. This article summarizes the advances in aerobic rice management researches in the North China Plain, focusing on yield formation and its bottleneck. High-yielding and good-quality aerobic rice varieties adapted to aerobic soil conditions have been released officially and adopted by farmers in North China. The varieties Handao 502 and Handao 297 have been recognized as the most promising varieties reaching a yield level ranging 3.5-5.0 t ha-1 with 450-650 mm water input. Compared with lowland rice, water input in aerobic rice was more than 50% lower, and water productivity was 60% higher. Researches on responses of rice cultivars to nitrate nitrogen （N） and ammonium N supplied at early growth stages provided the first evidence for a preference of aerobic rice HD297 for nitrate N supply, compared with the lowland rice variety. Zinc uptake studies demonstrated that introduction of aerobic rice system on calcareous soils may increase zinc deficiency problems. Sink size was identified as the limitation of aerobic rice yield, because its spikelet number m-2 was too low （20000-24 000） compared with the lowland rice. For future research, more attention is suggested to be paid to yield formation focusing on effects of water regimes on tiller dynamics. Understanding of nutrient uptake and response to fertilization effects are also urgently required to establish optimized crop management technology. Additionally, alternative cropping systems based on aerobic rice should be established, and key sustainability and environmental impact issues in the systems need to be identified.
基金Supported by A Research Grant of Center for Translational Molecular Medicine, The Netherlands, to van Turenhout STGrant of Nycomed B.V., Hoofddorp to "the Amsterdam Gut-club", The Netherlands+1 种基金The Netherlands Organization for Health Research and Development, ZonMW, No. 50-50115-98-060,project 63000004The original trial was registered under IS-RCTN57917442 at Current Controlled Trials (www.controlled-trials.com)
文摘AIM: To improve the interpretation of fecal immunochemical test (FIT) results in colorectal cancer (CRC) cases from screening and referral cohorts. METHODS: In this comparative observational study, two prospective cohorts of CRC cases were compared. The first cohort was obtained from 10 322 average risk subjects invited for CRC screening with FIT, of which, only subjects with a positive FIT were referred for colonoscopy. The second cohort was obtained from 3637 subjects scheduled for elective colonoscopy with a positive FIT result. The same FIT and positivity threshold (OC sensor; ≥ 50 ng/mL) was used in both cohorts. Colonoscopy was performed in all referral subjects and in FIT positive screening subjects. All CRC cases were selected from both cohorts. Outcome measurements were mean FIT results and FIT scores per tissue tumor stage (T stage). RESULTS: One hundred and eighteen patients with CRC were included in the present study: 28 cases obtained from the screening cohort (64% male; mean age 65 years, SD 6.5) and 90 cases obtained from the referral cohort (58% male; mean age 69 years, SD 9.8). The mean FIT results found were higher in the referral cohort (829 ± 302 ng/mLvs 613 ± 368 ng/mL,P = 0.02). Tissue tumor stage (T stage) distribution was dif-ferent between both populations [screening population: 13 (46%) T1, eight (29%) T2, six (21%) T3, one (4%) T4 carcinoma; referral population: 12 (13%) T1, 22 (24%) T2, 52 (58%) T3, four (4%) T4 carcinoma], and higher T stage was significantly associated with higher FIT results (P < 0.001). Per tumor stage, no significant difference in mean FIT results was observed (screening vs referral: T1 498 ± 382 ng/mL vs 725 ± 374 ng/mL, P = 0.22; T2 787 ± 303 ng/mL vs 794 ± 341 ng/mL, P = 0.79; T3 563 ± 368 ng/mLvs 870 ± 258 ng/mL,P = 0.13; T4 not available). After correction for T stage in logistic regression analysis, no significant differences in mean FIT results were observed between both types of cohorts (P = 0.10). CONCLUSION: Differences in T stage distribution
