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Ju X.,Northwest Agriculture and Forestry University | Wu P.,Northwest Agriculture and Forestry University | Weckler R.P.,Oklahoma State University | Zhang L.,Northwest Agriculture and Forestry University | Zhu D.,Institute of Water Saving Agriculture in Arid Regions of China
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2016

The chosen of lateral layout is the basis of hydraulic design of micro-irrigation laterals. A simple and easily adaptable analytical approach was developed for the hydraulic design of micro-irrigation laterals laid on uniformly sloping grounds based on the appropriate layouts. Two indictors for comparing the emitter flow variation and inlet working pressure head from the paired layout and single downhill layout were proposed based on the analytical models of micro-irrigation laterals. By evaluating the effects of micro-irrigation laterals layouts on the emitter flow variation and working pressure head, the application condition for paired layout was suggested as the best manifold position is not less than 0.13. When the best manifold position is less than 0.13, the micro-irrigation lateral was proposed to use the single downhill layout in order to save the extra cost of material and installation from the paired layout. The design procedure for hydraulic design of micro-irrigation laterals was revised by considering the determination of appropriate layout. Two design cases covering various conditions indicated that the best manifold position criterion for determining the appropriate layout is more effective than the value of ground slope proposed by Keller method. The proposed approach could produce accurate results for practical purposes. This research could provide valuable information for improving the hydraulic design of micro-irrigation systems. © 2016, Editorial Office of Nanotechnology and Precision Engineering. All right reserved.

Wang Y.,Northwest Agriculture and Forestry University | Chen L.,Northwest Agriculture and Forestry University | Du Y.,Northwest Agriculture and Forestry University | Yang Z.,Northwest Agriculture and Forestry University | And 3 more authors.
Field Crops Research | Year: 2014

GA-insensitive (GAI) dwarfing genes Rht-B1b and Rht-D1b have been widely used to reduce plant height, increase yield and improve harvest index, but they also express shorter coleoptiles and poor seedling vigor. GA-responsive dwarfing genes, such as Rht13 have potential for wheat improvement since they may not be associated with the latter effects. In this study, the effects of dwarfing genes Rht-D1b and Rht13 on plant height, coleoptile length, seedling root characters and yield components were investigated and compared in field environments in northwest China, using F2:3 and F3:4 lines derived from a cross between the Chinese winter wheat Xinong223 (Rht-D1b) and Magnif M1 (Rht13). The results showed that both Rht13 and Rht-D1b significantly reduced internode length and plant height. GA-responsive (GAR) dwarfing gene Rht13 reduced plant height by 16.5%, but did not affect coleoptile length or seedling root characters. Rht13 lines demonstrated better seedling vigor with greater potential for seedling establishment in the field. The GAI dwarfing gene Rht-D1b was associated with shorter plant height (22.0% in general) along with shorter coleoptile length, shorter total root length, smaller root surface area, and less root volume. These phenotypes may contribute to lower seedling vigor and poorer seedling emergence in the field. The GAR dwarfing gene Rht13 could compensate for some of the negative effect of the GAI dwarfing gene Rht-D1b on root surface area and root volume, which could benefit the root system. The combination of these two dwarfing genes produced even shorter plants (40.3% in general) and resulted in the shortest distance from spike to flag-leaf ligule. Rht-D1b did not affect the diameter of stems and flag leaf size adversely, while Rht13 narrowed the diameter of stems (except the peduncle) and narrowed flag leaf width. Grain number spike-1 and number of fertile tillers plant-1 was similar between lines with single dwarfing gene (Rht-D1b or Rht13) and tall lines, but less grain number spike-1 was observed in lines with double dwarfing genes. 1000-kernel weight was significantly reduced by Rht13, while Rht-D1b had no significant effect on 1000-kernel weight. In the rainfed winter wheat environments encountered here, Rht13 and Rht-D1b reduced biomass plant-1 by 24.5% and 19.9% and grain yield plant-1 by 25.8% and 25.7%, respectively, but harvest index remained the same as tall lines in both Rht13 and Rht-D1b dwarf lines. © 2014 Elsevier B.V.

Wang Y.,Northwest University, China | Du Y.,Northwest University, China | Yang Z.,Northwest University, China | Chen L.,Northwest University, China | And 3 more authors.
Field Crops Research | Year: 2015

Rht8 is the only GA-responsive dwarfing gene used in wheat grown in rainfed or irrigation-limited areas. To assess an alternative dwarfing gene, the effects of GA-responsive dwarfing gene Rht13 on plant height and some agronomic traits were compared with Rht8 in this study. The four homozygous genotypes of the F2 individuals, F2:3 and F3:4 lines derived from the cross between Jinmai47 (Rht8) and Magnif M1 (Rht13) were used to evaluate and compare the effects of Rht13 and Rht8. The coleoptile length and seedling root characteristics was conducted under laboratory conditions, while plant height and various yield components were evaluated in field environments in northwest China. Rht13 significantly shortened the length of all internodes (except the basal internode) and reduced final plant height by 30.3% (30.1cm) on average, while Rht8 mainly reduced peduncle length alone to obtain a plant stature shortened by only 15.7% (16.0cm). The greater effect of Rht13 on plant height resulted in the distance from spike to flag leaf ligule being decreased by 97.7%. The effect of Rht13 was even greater when combined with Rht8 (104.9%), such that the spikes failed to fully emerge from the flag leaf sheath. Compared with tall genotypes, coleoptile length and seedling root characteristics were not significantly affected by either Rht13 or Rht8, which might favor the utilization of Rht13 or Rht13+Rht8 in rainfed and irrigation-limited areas. Fewer grains spike-1 were observed in lines with Rht13 alone (18.2%) and with both dwarfing genes (Rht13+Rht8, 18.9%), whereas there was no significant difference between the lines with Rht8 alone and tall lines. Rht13 and Rht8 reduced biomass plant-1 by 27.9% and 25.2% and grain yield plant-1 by 29.0% and 17.4%, respectively. Rht13 did not affect 1000-kernel weight and harvest index whereas Rht8 significantly increased 1000-kernel weight and harvest index. In the rainfed winter wheat environment encountered in northwest China, Rht13 reduced grain number spike-1 significantly. This effect may be due to the very short distance from spike to flag leaf ligule. This undesirable effect may be improved through selection. If so, then there is potential for using Rht13 in wheat improvement in rainfed and irrigation-limited areas. © 2015 Elsevier B.V.

Zheng J.,Northwest University, China | Yang Z.,Northwest University, China | Madgwick P.J.,Rothamsted Research | Carmo-Silva E.,Rothamsted Research | And 3 more authors.
PLoS ONE | Year: 2015

ERECTA encodes a receptor-like kinase and is proposed as a candidate for determining transpiration efficiency of plants. Two genes homologous to ERECTA in Arabidopsis were identified on chromosomes 6 (TaER2) and 7 (TaER1) of bread wheat (Triticum aestivum L.), with copies of each gene on the A, B and D genomes of wheat. Similar expression patterns were observed for TaER1 and TaER2 with relatively higher expression of TaER1 in flag leaves of wheat at heading (Z55) and grain-filling (Z73) stages. Significant variations were found in the expression levels of both TaER1 and TaER2 in the flag leaves at both growth stages among 48 diverse bread wheat varieties. Based on the expression of TaER1 and TaER2, the 48 wheat varieties could be classified into three groups having high (5 varieties), medium (27 varieties) and low (16 varieties) levels of TaER expression. Significant differences were also observed between the three groups varying for TaER expression for several transpiration efficiency (TE)- related traits, including stomatal density (SD), transpiration rate, photosynthetic rate (A), instant water use efficiency (WUEi) and carbon isotope discrimination (CID), and yield traits of biomass production plant-1 (BYPP) and grain yield plant-1 (GYPP). Correlation analysis revealed that the expression of TaER1 and TaER2 at the two growth stages was significantly and negatively associated with SD (P<0.01), transpiration rate (P<0.05) and CID (P<0.01), while significantly and positively correlated with flag leaf area (FLA, P<0.01), A (P<0.05), WUEi (P<0.05), BYPP (P<0.01) and GYPP (P<0.01), with stronger correlations for TaER1 than TaER2 and at grain-filling stage than at heading stage. These combined results suggested that TaER involved in development of transpiration efficiency -related traits and yield in bread wheat, implying a function for TaER in regulating leaf development of bread wheat and contributing to expression of these traits. Moreover, the results indicate that TaER could be exploitable for manipulating important agronomical traits in wheat improvement. © 2015 Zheng et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Yasir T.A.,Northwest University, China | Min D.,Northwest University, China | Chen X.,Northwest University, China | Condon A.G.,CSIRO | And 2 more authors.
Agricultural Water Management | Year: 2013

Drought is a major issue affecting crop grain yield. Augmenting grain yield and crop water use efficiency (WUE) under drought is crucial for enhancing world crop production and food availability. Relationships of carbon isotope discrimination (Δ) with gas exchange parameters, yield traits and SPAD (leaf relative chlorophyll content) values were examined on a collection of 49-wheat (Triticum aestivum L.) genotypes under two levels of restricted irrigation in a rainout shelter. Water stress was applied at grain filling stage. The highest water-stress treatment received 40% less water than the milder-stress treatment. Significant and positive correlations were found between Δ and photosynthesis rate (A), stomatal conductance (gs), transpiration rate (E), and the ratio of intercellular CO2 concentration to ambient CO2 concentration (Ci/Ca), while significant and negative correlations were obtained between Δ and intrinsic water use efficiency (iWUE) under both water regimes. Strong positive correlations of Δ with grain yield (GY), biomass (BM) and harvest index (HI) were also observed in both water regimes, but no correlation was observed between Δ and SPAD values. Mean values of all other parameters were calculated for the five genotypes based on Δ value, i.e. the five genotypes which produced the highest Δ and five genotypes which produced the lowest Δ. It was found that mean values for all the parameters were increased for the high Δ genotypes and decreased for low Δ genotypes except for iWUE in both water regimes. These results suggest that Δ may be a good trait as an indirect selection criterion for genotypic improvement in drought tolerance of wheat under restricted irrigation, especially in conditions similar to those encountered here where limited water was applied during grain filling. © 2012 Elsevier B.V.

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