C and N isotopic compositions (mean±SD) of muscle, hair tip, hair base, and fat of free-living wild boar harvested in different areas.

<p>C and N isotopic compositions (mean±SD) of muscle, hair tip, hair base, and fat of free-living wild boar harvested in different areas.</p

Photosynthetic Diffusional Constraints Affect Yield in Drought Stressed Rice Cultivars during Flowering

<div><p>Global production of rice (<i>Oryza sativa</i>) grain is limited by water availability and the low ‘leaf-level’ photosynthetic capacity of many cultivars. <i>Oryza sativa</i> is extremely susceptible to water-deficits; therefore, predicted increases in the frequency and duration of drought events, combined with future rises in global temperatures and food demand, necessitate the development of more productive and drought tolerant cultivars. We investigated the underlying physiological, isotopic and morphological responses to water-deficit in seven common varieties of <i>O. sativa</i>, subjected to prolonged drought of varying intensities, for phenotyping purposes in open field conditions. Significant variation was observed in leaf-level photosynthesis rates (<i>A</i>) under both water treatments. Yield and <i>A</i> were influenced by the conductance of the mesophyll layer to CO₂ (<i>g</i>_m) and not by stomatal conductance (<i>g</i>_s). Mesophyll conductance declined during drought to differing extents among the cultivars; those varieties that maintained <i>g</i>_m during water-deficit sustained <i>A</i> and yield to a greater extent. However, the variety with the highest <i>g</i>_m and yield under well-watered conditions (IR55419-04) was distinct from the most effective cultivar under drought (Vandana). Mesophyll conductance most effectively characterises the photosynthetic capacity and yield of <i>O. sativa</i> cultivars under both well-watered and water-deficit conditions; however, the desired attributes of high <i>g</i>_m during optimal growth conditions and the capacity for <i>g</i>_m to remain constant during water-deficit may be mutually exclusive. Nonetheless, future genetic and physiological studies aimed at enhancing <i>O. sativa</i> yield and drought stress tolerance should investigate the biochemistry and morphology of the interface between the sub-stomatal pore and mesophyll layer.</p></div

Changes in yield and photosynthesis in relation to modification of diffusive resistances to CO₂ uptake following water-stress.

<p>Those varieties that experienced smaller reductions in parameters were more tolerant of drought. a) relationship between Δyield and Δ<i>g</i>_s (linear regression: R² = 0.337; <i>F</i>_1,4 = 2.032; <i>P</i> = 0.227); b) relationship between Δyield and Δ<i>g</i>_m (linear regression: R² = 0.134; <i>F</i>_1,4 = 0.618; <i>P</i> = 0.476); c) relationship between Δyield and Δ<i>g</i>_tot (linear regression: R² = 0.0818; <i>F</i>_1,4 = 0.356; <i>P</i> = 0.583); d) relationship between Δ<i>A</i> and Δ<i>g</i>_s (linear regression: R² = 0.0003; <i>F</i>_1,4 = 0.00106; <i>P</i> = 0.976); e) relationship between Δ<i>A</i> and Δ<i>g</i>_m (linear regression: R² = 0.742; <i>F</i>_1,4 = 11.527; <i>P</i> = 0.0274); f) relationship between Δ<i>A</i> and Δ<i>g</i>_tot (linear regression: R² = 0.715; <i>F</i>_1,4 = 10.042; <i>P</i> = 0.0339), and; g) relationship between Δyield and Δ<i>A</i> (linear regression: R² = 0.427; <i>F</i>_1,4 = 2.979; <i>P</i> = 0.159). Error bars as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109054#pone-0109054-g001" target="_blank">Figure 1</a>. Numbers next to data points indicate <i>Oryza sativa</i> variety as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109054#pone-0109054-g001" target="_blank">Figure 1</a>.</p

Sampling areas (TC: Tyrrhenian Coast, MA: Maremma, CP: Central plains).

<p>Sampling areas (TC: Tyrrhenian Coast, MA: Maremma, CP: Central plains).</p

Carbon isotope discrimination (‰) of the flag leaf pellet (bulk) and soluble sugars of seven rice cultivars grown under drought and well-watered conditions in ‰.

<p>Values indicate the mean of six plants; ± indicates the standard error of mean; different letters indicate significant differences (P≤0.05) among means according to an ANOVA.</p><p>Carbon isotope discrimination (‰) of the flag leaf pellet (bulk) and soluble sugars of seven rice cultivars grown under drought and well-watered conditions in ‰.</p

Morphological traits (mean±SD) of female (F) and male (M) wild boars included in the trial according to harvesting area (TC = Tyrrhenian Coast; MA = Maremma, CP = Central plains) and sex.

<p>Morphological traits (mean±SD) of female (F) and male (M) wild boars included in the trial according to harvesting area (TC = Tyrrhenian Coast; MA = Maremma, CP = Central plains) and sex.</p

Interaction of yield and <i>A</i> with transpiration efficiency (<i>A</i>/<i>g</i>_s) and the ratio of <i>g</i>_m to <i>g</i>_s in well-watered (open symbols) and drought conditions (closed symbols): a) relationship between yield and <i>A</i>/<i>g</i>_s under full (linear regression: R² = 0.0595; <i>F</i>_1,4 = 0.253; <i>P</i> = 0.641) and water-stressed (linear regression: R² = 0.434; <i>F</i>_1,4 = 3.072; <i>P</i> = 0.155) conditions; b) relationship between harvest index (<i>HI</i>) and <i>A</i>/<i>g</i>_s under full (linear regression: R² = 0.205; <i>F</i>_1,4 = 1.032; <i>P</i> = 0.367) and water-stressed (linear regression: R² = 0.185; <i>F</i>_1,4 = 0.909; <i>P</i> = 0.394) conditions; c) relationship between yield and <i>g</i>_m:<i>g</i>_s (linear regression: R² = 0.456; <i>F</i>_1,10 = 8.379; <i>P</i> = 0.

<p>Error bars as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109054#pone-0109054-g001" target="_blank">Figure 1</a>. Numbers next to data points indicate <i>Oryza sativa</i> variety as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109054#pone-0109054-g001" target="_blank">Figure 1</a>.</p

Measurements of (a) photosynthesis rate (<i>A</i>), (b) stomatal conductance (<i>g</i>_s), (c) mesophyll conductance (<i>g</i>_m), and (d) intrinsic transpiration efficiency (<i>A</i>/<i>g</i>_s) in control and water-stressed leaves of the seven <i>Oryza sativa</i> genotypes.

<p>The measurements were made on the flag leaf in saturating PPFD (1400 µmol m⁻²s⁻¹), with relative humidity ranging between 45–55%, and a leaf temperature of 30°C. Data are means of 4 to 7 plants per treatment. Error bars as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109054#pone-0109054-g001" target="_blank">Figure 1</a>. Different letters denote significant differences among means derived using a factorial ANOVA and Tukey <i>post-hoc</i> test.</p

Interaction of diffusive conductance parameters to CO₂ uptake with yield and photosynthesis (<i>A</i>) under well-watered (open symbols) and drought conditions (closed symbols): a) relationship between yield and stomatal conductance (<i>g</i>_s) (linear regression: R² = 0.696; <i>F</i>_1,10 = 22.900; <i>P</i> = 0.000740); b) relationship between <i>A</i> and <i>g</i>_s (linear regression: R² = 0.873; <i>F</i>_1,11 = 75.721; <i>P</i> = 2.911×10^–6); c) relationship between yield and mesophyll conductance (<i>g</i>_m) (linear regression: R² = 0.850; <i>F</i>_1,10 = 56.611; <i>P</i> = 2.911×10^–5); d) relationship between <i>A</i> and <i>g</i>_m (linear regression: R² = 0.952; <i>F</i>_1,11 = 217.071; <i>P</i> = 1.376×10^–8); e) relationship between yield and total conductance (<i>g</i>_tot) (linear regression: R<sup

<p>Error bars as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109054#pone-0109054-g001" target="_blank">Figure 1</a>. Numbers next to data points indicate <i>Oryza sativa</i> variety as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109054#pone-0109054-g001" target="_blank">Figure 1</a>.</p

Land cover (%) and climatic data (mean annual temperature, mean annual rainfall and xerothermic index) of the three areas (TC: Tyrrhenian Coast, MA: Maremma, CP: Central plains).

<p>Land cover (%) and climatic data (mean annual temperature, mean annual rainfall and xerothermic index) of the three areas (TC: Tyrrhenian Coast, MA: Maremma, CP: Central plains).</p