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Hu K.,China Agricultural University | Li Y.,University of Melbourne | Chen W.,CAS Research Center for Eco Environmental Sciences | Chen D.,University of Melbourne | And 5 more authors.
Journal of Environmental Quality

Understanding water and N transport through the soil pro. le is important for effcient irrigation and nutrient management to minimize nitrate leaching to the groundwater, and to promote agricultural sustainable development in desert oases. In this study, a process-based water and nitrogen management model (WNMM) was used to simulate soil water movement, nitrate transport, and crop growth (maize [Zea mays L.]) under desert oasis conditions in northwestern China. The model was calibrated and validated with a field experiment. The model simulation results showed that about 35% of total water input and 58% of the total N input were leached to <1.8 m depth under traditional management practice. Excessive irrigation and N fertilizer application, high nitrate concentration in the irrigation water, together with the sandy soil texture, resulted in large nitrate leaching. Nitrate leaching was significantly reduced under the improved management practice suggested by farm extension personnel; however, the water and nitrate inputs still far exceeded the crop requirements. More than 1700 scenarios combining various types of irrigation and fertilizer practices were simulated. Quantitative analysis was conducted to obtain the best management practices (BMPs) with simultaneous consideration of crop yield, water use efficiency, fertilizer N use efficiency, and nitrate leaching. The results indicated that the BMPs under the specific desert oasis conditions are to irrigate the maize with 600 mm of water in eight times with a single fertilizer application at a rate of 75 kg N ha-1. Copyright © 2010 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved. Source

Liang H.,China Agricultural University | Liang H.,McGill University | Qi Z.,McGill University | Hu K.,China Agricultural University | And 2 more authors.
Journal of Environmental Management

Nitrate contamination of groundwater is an environmental concern in intensively cultivated desert oases where this polluted groundwater is in turn used as a major irrigation water resource. However, nitrate fluxes from root zone to groundwater are difficult to monitor in this complex system. The objectives of this study were to validate and apply the WHCNS (soil Water Heat Carbon Nitrogen Simulator) model to simulate water drainage and nitrate leaching under different irrigation and nitrogen (N) management practices, and to assess the utilization of groundwater nitrate as an approach to remediate nitrate contaminated groundwater while maintain crop yield. A two-year field experiment was conducted in a corn field irrigated with high nitrate groundwater (20 mg N L-1) in Alxa, Inner Mongolia, China. The experiment consisted of two irrigation treatments (Istd, standard, 750 mm per season; Icsv, conservation, 570 mm per season) factorially combined with two N fertilization treatments (Nstd, standard, 138 kg ha-1; Ncsv, conservation, 92 kg ha-1). The validated results showed that the WHCNS model simulated values of crop dry matter, yield, soil water content and soil N concentration in soil profile all agreed well with the observed values. Compared to the standard water management (Istd), the simulated drainage and nitrate leaching decreased about 65% and 59%, respectively, under the conservation water management (Icsv). Nearly 55% of input N was lost by leaching under the IstdNstd and IstdNcsv treatments, compared to only 26% under the IcsvNstd and IcsvNcsv treatments. Simulations with more than 240 scenarios combing different levels of irrigation and fertilization indicated that irrigation was the main reason leading to the high risk of nitrate leaching, and the nitrate in irrigation groundwater can be best utilized without corn yield loss when the total irrigation was reduced from the current 750 mm to 491 mm. This reduced irrigation rate facilitated the use of approximately 42 kg N ha-1 yr-1 of nitrate from groundwater, which would gradually improve the groundwater quality. Future field studies on nitrate leaching in this area are suggested to investigate water and N dynamics under irrigation rates near 490 mm per season. © 2016 Elsevier Ltd. Source

Zhang Z.,Northwest Agriculture and Forestry University | Zhang Z.,Research Center for Jujube Engineering and Technology | Zhang Z.,Key Comprehensive Laboratory of Forestry | Wei T.,Ningxia Academy of Agricultural and Forestry science | And 6 more authors.
Tree Genetics and Genomes

The Chinese jujube (Ziziphus jujuba Mill., 2n = 2 × = 24), one of the most popular fruit trees in China, is widely cultivated and utilized in Asia. High-density genetic linkage maps are valuable resources for molecular breeding and functional genomics; however, they are still under-developed for the jujube. The genotyping by sequencing (GBS) strategy could be an efficient and cost-effective tool for single nucleotide polymorphism (SNP) discovery based on the sequenced jujube genome. Here, we report a new high-density genetic map constructed using GBS technology. An F1 population with 145 progenies and their parents (‘Dongzao’ × ‘Zhongningyuanzao’) were sequenced on the Illumina HiSeq 4000 platform. In total, 79.8 Gb of raw data containing 256,708,177 paired-end reads were generated. After data filtering and SNP genotyping, 40,372 polymorphic SNP markers were developed between the parents and 2540 (1756 non-redundant) markers were mapped onto the integrated genetic linkage map. The map spanned 1456.53 cM and was distributed among 12 linkage groups, which is consistent with the haploid chromosome number of the jujube. The average marker interval was 0.88 cM. The genetic map allowed us to anchor 224 Mb (63.7 %) of scaffolds from the sequenced ‘Junzao’ genome, containing 52 newly anchored scaffolds, which extended the genome assembly by 7 Mb. In conclusion, GBS technology was applied efficiently for SNP discovery in this study. The high-density genetic map will serve as a unique tool for molecular-assisted breeding and genomic studies, which will contribute to further research and improvement of the jujube in the near future. © 2016, Springer-Verlag Berlin Heidelberg. Source

Zhu L.,Ningxia University | Zhu L.,Ningxia Academy of Agricultural and Forestry science | Zhu L.,Northwest University, China | Li S.H.,Ningxia Academy of Agricultural and Forestry science | And 4 more authors.
Journal of Agronomy and Crop Science

Carbon isotope discrimination (Δ) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of high cost for Δ analysis, attempts have been made to identify alternative screening criteria. Ash content (ma) has been proposed as an alternative criterion for Δ in wheat and barley. A pot experiment was conducted to analyse the relationship between Δ, mineral content and gas exchange parameters in seedlings and leaves of bread wheat (Triticum aestivum L.). Plants of 10 genotypes were cultivated under three different water regimes corresponding to moderate (T3), intermediate (T2) and severe drought (T1) stress obtained by maintaining soil humidity at 75 %, 55 % and 45 % of the humidity at field capacity respectively. Δ and ma in seedlings and leaves showed significant differences among the three water treatments. Significant positive correlations were found between Δ and ma in seedlings and leaves at elongation and anthesis stages in severe drought stress (T1). Δ was negatively associated with potassium (K) content in intermediate drought stress (T2) and positively with magnesium (Mg) content in T2 and T3 (moderate drought stress) in flag leaf at anthesis. There were negative correlations between Δ and single-leaf intrinsic water-use efficiency (WT) in T2 and T3 at anthesis stage. Stronger positive associations were noted between Δ and stomatal conductance (gs) in T1 and T2 than in T3 at anthesis. These results suggested that Δ is a good trait as an indirect selection criterion for genotypic improvement in transpiration efficiency, while ma is a possible alternative criterion of Δ in wheat vegetative organs, especially in stressed environments. Significant association was found between Δ and K, Mg and Ca contents that would merit being better investigated. © 2009 Blackwell Verlag GmbH. Source

Liu S.,Nanjing Agricultural University | Xu C.,Institute of Medicinal Plant Development | Chen J.,Institute of Medicinal Plant Development | Guo Q.,Nanjing Agricultural University | And 4 more authors.
Zhongguo Zhongyao Zazhi

Objective: To investigate the controlling effects of bionic glue on Paratrioza sinica. Method: P. sinica and bionic glue were chosen as materials to investigate the adhesive rate, mortality rate, and study the effects of behavior of P. sinica and growth of leaves sprayed with bionic glue. Result: Spraying of the bionic glue can significantly increase the adhesive rate of P. sinica with no obviously repellency, and it can be used to control the adults of P sinaca in field with no significant effect on the growth of wolfberry leaves. Conclusion: Bionic glue has significant controlling effects on adults of P. sinica, it can be used as an eliminator of adults of P. sinica in field at the beginning of the vegetation season to suppress of the development of P. sinica population. Source

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