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Author (up) Bowsher, A.W.; Milton, E.F.; Donovan, L.A. file  url
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  Title Comparison of Desert-Adapted Helianthus niveus (Benth.) Brandegee ssp. tephrodes (A. Gray) Heiser to Cultivated H. annuus L. for Putative Drought Avoidance Traits at Two Ontogenetic Stages Type Journal Article
  Year 2016 Publication Helia Abbreviated Journal  
  Volume 39 Issue 64 Pages 1-19  
  Keywords abiotic stress; crop improvement; leaf pubescence; NDVI; rooting depth rate; water use efficiency  
  Abstract Water availability is a major factor limiting plant productivity in both natural and agronomic systems. Identifying putative drought resistance traits in crops and their wild relatives may be useful for improving crops grown under water-limiting conditions. Here, we tested the expectation that a desert-dwelling sunflower species, Helianthus niveus ssp. tephrodes (TEPH) would exhibit root and leaf traits consistent with greater ability to avoid drought than cultivated sunflower H. annuus (ANN) in a common garden environment. We compared TEPH and ANN at both the seedling and mature stages under well-watered greenhouse conditions. For traits assessed at the seedling stage, TEPH required a longer time to reach a rooting depth of 30 cm than ANN, and the two species did not differ in root:total biomass ratio at 30 cm rooting depth, contrary to expectations. For traits assessed at the mature stage, TEPH had a higher instantaneous water use efficiency and photosynthetic rate on a leaf area basis, but a lower photosynthetic rate on a mass basis than ANN, likely due to TEPH having thicker, denser leaves. Contrary to expectations, ANN and TEPH did not differ in leaf instantaneous stomatal conductance, integrated water-use efficiency estimated from carbon isotope ratio, or nitrogen concentration. However, at both the seedling and mature stages, TEPH exhibited a lower normalized difference vegetative index than ANN, likely due to the presence of dense leaf pubescence that could reduce heat load and transpirational water loss under drought conditions. Thus, although TEPH root growth and biomass allocation traits under well-watered conditions do not appear to be promising for improvement of cultivated sunflower, TEPH leaf pubescence may be promising for breeding for drought-prone, high radiation environments.  
  Call Number Serial 1809  
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Author (up) Li, D.; Liu, H.; Qiao, Y.; Wang, Y.; Cai, Z.; Dong, B.; Shi, C.; Liu, Y.; Li, X.; Liu, M. file  url
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  Title Effects of elevated CO2 on the growth, seed yield, and water use efficiency of soybean (Glycine max (L.) Merr.) under drought stress Type Journal Article
  Year 2013 Publication Agricultural Water Management Abbreviated Journal Agricultural Water Management  
  Volume 129 Issue Pages 105-112  
  Keywords Elevated CO2 concentration (EC); Drought; Seed yield; Biomass allocation; Water use efficiency (WUE); Photosynthesis  
  Abstract This study aims to evaluate the effects of elevated carbon dioxide (EC) on soybean growth in the water-deficient region of Huang-Huai-Hai Plain, China. A pot experiment involving two CO2 concentrations (ambient, 380.1 ± 32.2 μmol mol−1 and elevated, 740.6 ± 45.4 μmol mol−1) and two water levels (normal and drought) were conducted in enclosed top chambers. The results showed that plant height, leaf area, and shoot dry weight were increased by 25.4%, 15.8%, and 33.4% under normal water and EC conditions, respectively, at the seed-filling stage. Seed yield per plant was also improved by 25.3%. Under drought conditions, EC did not show a significant effect on plant height, leaf area, and seed yield. However, shoot dry weight was increased by 56% at the seed-filling stage. This increase was due to the higher biomass allocation toward the stems. Under normal water conditions, the photosynthetic rate (Pn) was higher (21.743.3%) in EC than in ambient carbon dioxide (AC) at the seed-filling stage. Under drought conditions, Pn remained high, but the transpiration rate (Tr) was reduced by EC. In addition, the water use efficiency at yield and biomass levels (WUEyield and WUEbiomass) were increased by 26.2% and 55.4% under normal water conditions in EC at the seed-filling stage. However, they were only increased by 5.9% and 13.4%, respectively, under drought conditions. These results suggested that EC improved the growth and WUE of soybean more effectively under normal water conditions than under drought stress conditions. In conclusion, EC did not mitigate drought-induced inhibition of seed yield in soybean, although it increased Pn and WUE. Soybean should be cropped under well irrigation regimes or at regions with sufficient precipitation to adapt and take full advantage of EC.  
  Call Number Serial 1150  
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