No abstract

Aegilops tauschii is the diploid progenitor of the bread wheat D-genome. It originated from Iran and is a source of abiotic stress tolerance genes. However, little is known about the molecular events of salinity tolerance in Ae. tauschii. This study investigates the leaf transcriptional changes associated with long-term salt stress. Total RNA extracted from leaf tissues of control and salt-treated samples was sequenced using the Illumina technology, and more than 98 million high-quality reads were assembled into 255,446 unigenes with an average length of 1398 bp and an N50 of 2269 bp. Functional annotation of the unigenes showed that 93,742 (36.69%) had at least a significant BLAST hit in the SwissProt database, while 174,079 (68.14%) showed significant similarity to proteins in the NCBI nr database. Differential expression analysis identified 4506 salt stress-responsive unigenes. Bioinformatic analysis of the differentially expressed unigenes (DEUs) revealed a number of biological processes and pathways involved in the establishment of ion homeostasis, signaling processes, carbohydrate metabolism, and post-translational modifications. Fine regulation of starch and sucrose content may be important features involved in salt tolerance in Ae. tauschii. Moreover, 82% of DEUs mapped to the D-subgenome, including known QTL for salt tolerance, and these DEUs showed similar salt stress responses in other accessions of Ae. tauschii. These results could provide fundamental insight into the regulatory process underlying salt tolerance in Ae. tauschii and wheat and facilitate identification of genes involved in their salt tolerance mechanisms.

The application of plant nutrients with irrigation water (fertigation) is a cost‐effective and efficient method for fertilizer application to enhance crop production and reduce potential environmental problems in comparison to conventional methods. In this study, the distribution uniformity of fertigation and fertilizer losses through runoff and deep percolation were evaluated at field scale in different furrow irrigation regimes and soils. A numerical fertigation model was calibrated and validated. Experiments were carried out in three soil textures and potassium nitrate was injected during the first half of the irrigation (FH), in the second half (SH) and during the entire irrigation event (T). These options were conducted under free‐draining and blocked‐end conditions with a cutback method. The distribution uniformities of low half (DULH) and low quarter (DULQ) of water and fertilizer were calculated to evaluate different fertigation scenarios. There were no significant differences among distribution uniformities in the three fertilizer application treatments (FH, SH, T). However, injection in the first half and during the entire irrigation event was better in terms of distribution uniformity and infiltrated fertilizer. The best case in blocked‐end conditions was injection in the second half of the irrigation event, preferably starting before completion of the advanced phase. In this case, fertilizer losses due to runoff from the outlet were zero and distribution uniformity was somewhat higher, whereas in free‐drainage conditions, fertilizer application during the first half of the irrigation provided acceptable fertilizer uniformity and lower fertilizer losses due to runoff. No significant difference was observed between the distribution uniformity of free‐drainage and blocked‐end experiments. A fertigation model was applied to the experimental data and the results showed good agreement with the field data. Measurements also showed that water and fertilizer losses due to deep percolation in fertigation was not a concern when proper irrigation parameters were selected, such as inflow rate. Copyright © 2012 John Wiley & Sons, Ltd.

In new agricultural practices, joint application of water and fertilizer has been become common. Uniform distribution of fertilizer in soil and in plant growth duration is possible by this procedure. The main objective of this study was to investigate furrow fertigation management effects on distribution uniformity and runoff losses of nitrate in a cornfield, and validate a numerical fertigation model. A field experiment was carried out with seed corn at 12 experiments with a complete randomized block design during 2 years. Nitrogen requirement was determined by soil analysis and accomplished in four stages of the growth: before cultivation, in seven leaves, shooting and earring stages which first section (before cultivation) was applied by manual distribution and others by fertigation. Potash and super phosphate fertilizers (based on soil analysis) were sprayed on soil before planting. Water requirement was estimated by using class a evaporation pan multiplied by plant (Kc) and pan coefficients. Nitrogen fertilizer was solved in irrigation water and injected at the last minutes of irrigation. The results showed that fertilizer distribution uniformity of the low quarter (DU LQ ) ranged from 85.7% to 91.5% in first year, and 69.9% to 95.5% in second year. While water DU LQ ranged from 74.1 to 98.2% in 2 years. Nitrate losses of surface runoff have ranged between 5.7 and 42.0% in first year according to the application time and the outflow flux. In second year, the nitrate losses decreased by adopting appropriate management based on the experiences of first year. The fertigation model was subsequently applied to the experimental data and results showed good agreement with field data.

Artemisinin is the most effective antimalarial drug that is derived from Artemisia annua. Amorpha-4,11-diene synthase (ADS) controls the first committed step in artemisinin biosynthesis. The ADS gene expression is regulated by transcription factors which bind to the cis-acting elements on the ADS promoter and are probably responsible for the ADS gene expression difference in the Artemisia species. To identify the elements that are significantly involved in ADS gene expression, the ADS gene promoter of the seven Artemisia species was isolated and comparative analysis was performed on the ADS promoter sequences of these species. Results revealed that some of the cis-elements were unique or in terms of number were more in the high artemisinin producer species, A. annua, than the other species. We have reported that the light-responsive elements, W-box, CAAT-box, 5'-UTR py-rich stretch, TATA-box sequence and tandem repeat sequences have been identified as important factors in the increased expression of ADS gene.