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Sheng-cai QIANG Fu-cang ZHANG Miles Dyck Yan ZHANG You-zhen XIANG Jun-liang FAN 《农业科学学报》2019,18(10):2369-2380
Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China. 相似文献
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Xiao-feng YUE Yan-lun JU Zi-zhu TANG Ya-meng ZHAO Xu-liang JIAO Zhen-wen ZHANG 《农业科学学报》2019,18(9):2052-2062
The effects of the severity and timing of leaf removal(LR) on the amino acids of Sauvignon Blanc grapes and wines were studied during the 2017 growing season. High-performance liquid chromatography(HPLC) was used to analyze the amino acids profiles of grape berries and wines. The basal leaves were removed at three time points(40, 56 and 72 days after flowering, named LR40, LR56 and LR72, respectively) at two severity levels(one at which the first, third, and fifth basal leaves of each shoot were removed(50% level); and another at which the first six basal leaves were removed(100% level)). The results showed that leaf removal had little impact on total soluble solids(°Brix), titratable acidity, pH or berry weight. The LR72-50% treated grapes had higher berry weight, titratable acidity and °Brix than those of the other treatments. The highest concentrations of total amino acids and of total amino acids except proline were detected in LR72-50% treated grapes(2 952.58 and 2 764.36 mg L~(-1), respectively); the lowest were detected in LR72-100% treated grapes(2 172.82 and 2 038.71 mg L~(-1), respectively). LR72-50% treatment significantly promoted the synthesis of aspartic acid, serine, arginine, alanine, aminobutyric acid and proline at both severity levels for grapes, the concentrations of all of these amino acids were increased relative to the control concentrations. The LR72-50%, LR40-100% and LR72-100% treated wines had higher total amino acids concentrations and higher concentrations of some individual amino acids, such as arginine, alanine and serine, than did the control wines. Of all the amino acids studied, glycine, tyrosine, cysteine, methionine and lysine were not significantly influenced by the timing or severity basal defoliation in grapes and wines. The present study reveals the effects of the timing and severity of leaf removal on the amino acids profiles of grapes and wines. 相似文献
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龚春英 《吉林农业科技学院学报》2007,16(2):35-37
清末新政时期,张之洞在奏折中详细提出其改良监狱的思想,即改善监舍条件,修建文明监狱;教囚犯以工艺;选派专门官吏稽察监狱。其监狱改良思想的提出受到国际监狱改良思想的影响,体现了“中体西用”原则,同时也体现了近代中西法律思想文化交融碰撞的时代特征。这些主张大多为修律大臣沈家本所采纳,对近代监狱改良产生重要影响。 相似文献
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Feng-lian LÜ Miao-miao HOU Hong-tao ZHANG Asif Khan Muhammad Ayaz Ciren QIANGJIU Chang-lu HU Xue-yun YANG Ben-hua SUN Shu-lan ZHANG 《农业科学学报》2019,18(1):169-178
A high crop yield with the minimum possible cost to the environment is generally desirable. However, the complicated relationships among crop production, nitrogen (N) use efficiency and environmental impacts must be clearly assessed. We conducted a series of on-farm N application rate experiments to establish the linkage between crop yield and N2O emissions in the Guanzhong Plain in Northwest China. We also examined crop yield, partial factor productivity of applied N (PFPN) and reactive N (Nr) losses through a survey of 1 529 and 1 497 smallholder farms that grow wheat and maize, respectively, in the region. The optimum N rates were 175 and 214 kg ha–1 for winter wheat and summer maize, respectively, thereby achieving the yields of 6 799 and 7 518 kg ha–1, correspondingly, with low N2O emissions based on on-farm N rate experiments. Among the smallholder farms, the average N application rates were 215 and 294 kg ha–1 season–1, thus producing 6 490 and 6 220 kg ha–1 of wheat and maize, respectively. The corresponding PFPN values for the two crops were 36.8 and 21.2 kg N kg–1, and the total N2O emissions were 1.50 and 3.88 kg ha–1, respectively. High N balance, large Nr losses and elevated N2O emissions could be explained by the overdoses of N application and low grain yields under the current farming practice. The crop yields, N application rates, PFPN and total N2O for wheat and maize were 18 and 24% higher, 42 and 37% less, 75 and 116% higher, and 42 and 47% less, correspondingly, in the high-yield and high-PFPN group than in the average smallholder farms. In conclusion, closing the PFPN gap between the current average and the value for the high-yield and high-PFPN group would increase crop production and reduce Nr losses or the total N2O emissions for the investigated cropping system in Northwest China. 相似文献
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Cry1Ai-h-loop 2 is a mutant of Cry1Ai constructed by exchanging loop 2 from Cry1Ah protein and shows insecticidal activity against Helicoverpa armigera. The toxicity of Cry1 Ai-h-loop 2, in contrast to the very low toxicity of Cry1Ai, is closely associated with the eleven residues in the loop 2 region. To characterize the key sites of loop 2 in Cry1Ai-h-loop 2, alaninesubstituted mutants were generated. The toxicity of these mutants against H. armigera indicated that dual-mutant on Gly373 and Asn375 caused a significant decrease in toxic activity. ELISA binding and competition binding assays demonstrated that the reduction of toxicity in the mutant of interest was correlated with decreased binding affinity. 相似文献
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目的 应用中医传承辅助系统软件,挖掘分析张学文教授治疗原发性高血压病肝热血瘀证的用药规律。方法 收集张学文教授近5年治疗原发性高血压病肝热血瘀证的病例,采用关联规则、系统熵聚类等数据挖掘方法,分析张学文教授治疗原发性高血压病肝热血瘀证的用药经验和用药规律。结果 对筛选出的116首典型处方进行统计分析,得出处方中药物的使用频次、药物之间的关联规则、药物核心组合和新处方。结论 张学文教授诊治原发性高血压病肝热血瘀证,以天麻钩藤饮和(或)脑清通汤为基础方加减,多用平肝熄风、活血化瘀药以治标,再加补肾、安神等药以扶正,标本兼治。 相似文献
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张志澄先生(1910-1997),茶学专家,三十五年如一日地在江苏从事茶叶科研、生产和经营。他从全国各地大量地引进良种和设计并推广具有江苏特色的生态茶园,他对江苏省茶叶的发展做出了极大的贡献。今年是张志澄先生百年诞辰,特写此文纪念他。 相似文献