Ideotype Population Exploration: Growth, Photosynthesis, and Yield Components at Different Planting Densities in Winter Oilseed Rape (<i>Brassica napus</i> L.)

<div><p>Rapeseed is one of the most important edible oil crops in the world and the seed yield has lagged behind the increasing demand driven by population growth. Winter oilseed rape (<i>Brassica napus</i> L.) is widely cultivated with relatively low yield in China, so it is necessary to find the strategies to improve the expression of yield potential. Planting density has great effects on seed yield of crops. Hence, field experiments were conducted in Wuhan in the Yangtze River basin with one conventional variety (Zhongshuang 11, ZS11) and one hybrid variety (Huayouza 9, HYZ9) at five planting densities (27.0×10⁴, 37.5×10⁴, 48.0×10⁴, 58.5×10⁴, 69.0×10⁴ plants ha^–1) during 2010–2012 to investigate the yield components. The physiological traits for high-yield and normal-yield populations were measured during 2011–2013. Our results indicated that planting densities of 58.5×10⁴ plants ha^–1 in ZS11 and 48.0×10⁴ plants ha^–1 in HYZ9 have significantly higher yield compared with the density of 27.0×10⁴ plants ha^–1for both varieties. The ideal silique numbers for ZS11 and HYZ9 were ∼0.9×10⁴ (n m^–2) and ∼1×10⁴ (n m^-2), respectively, and ideal primary branches for ZS11 and HYZ9 were ∼250 (n m^–2) and ∼300 (n m^–2), respectively. The highest leaf area index (LAI) and silique wall area index (SAI) was ∼5.0 and 7.0, respectively. Moreover, higher leaf net photosynthetic rate (Pn) and water use efficiency (WUE) were observed in the high-yield populations. A significantly higher level of silique wall photosynthesis and rapid dry matter accumulation were supposed to result in the maximum seed yield. Our results suggest that increasing the planting density within certain range is a feasible approach for higher seed yield in winter rapeseed in China.</p></div

Dry matter biomass at pre-anthesis and post-anthesis in the normal-yield (NY) and high-yield (HY) populations of ZS11 and HYZ9 in 2011–2012 and 2012–2013 growing seasons.

<p>(A) Dry matter biomass at pre-anthesis and post-anthesis in the NY and HY populations of ZS11 and HYZ9 in 2011–2012. (B) Dry matter biomass at pre-anthesis and post-anthesis in the NY and HY populations of ZS11 and HYZ9 in 2012–2013. Different lower case letters indicate significant pairwise differences between means (p<0.05; Duncan's test).</p

The net photosynthetic rates (Pn), and water use efficiency (WUE) of leaves at different growing stages and post-anthesis in the normal-yield (NY) and high-yield (HY) populations of ZS11 and HYZ9 in 2012–2013 growing season.

<p>(A) and (B) Pn and WUE of leaves at different growing stages in the NY and HY populations of ZS11 and HYZ9, respectively. (C) and (D) Pn and WUE of leaves at post-anthesis in the NY and HY populations of ZS11 and HYZ9, respectively. The arrows indicate the flowering stage.</p

Numbers of primary branches and siliques per unit area of ZS11 and HYZ9 at five planting densities in 2010–2011 and 2011–2012 growing seasons.

<p>(A) and (B) Number of primary branches per unit area of ZS11 and HYZ9 in 2010–2011 and 2011–2012, respectively. (C) and (D) Number of siliques per unit area of ZS11 and HYZ9 in 2010–2011 and 2011–2012, respectively. Different lower case letters indicate significant pairwise differences between means (p<0.05; Duncan's test).</p

Leaf area index (LAI) at different growing stages and post-anthesis in the normal-yield (NY) and high-yield (HY) populations of ZS11 and HYZ9 in 2011–2012 and 2012–2013 growing seasons.

<p>(A) and (B) LAI at different growing stages in the NY and HY populations of ZS11 and HYZ9 in 2011–2012 and 2012–2013, respectively. (C) and (D) LAI at post-anthesis in the NY and HY populations of ZS11 and HYZ9 in 2011–2012 and 2012–2013, respectively. The arrows indicate the flowering stage.</p

Yield components of branches in ZS11 and HYZ9 in 2010–2011 and 2011–2012 growing seasons.

<p>Different letters within the same column indicate significant differences between the means determined by Duncan's multiple range test (<i>p</i><0.05). For the interaction terms: *, ** show the significance at 0.05 and 0.01 levels, ^†NS not significant.</p><p>Yield components of branches in ZS11 and HYZ9 in 2010–2011 and 2011–2012 growing seasons.</p

The silique wall area index (SAI) and silique wall photosynthesis in the normal-yield (NY) and high-yield (HY) populations of ZS11 and HYZ9 in 2011–2012 and 2012–2013 growing seasons.

<p>(A) and (B) SAI in the NY and HY populations of ZS11 and HYZ9 in 2011–2012 and 2012–2013, respectively. (C) and (D) The silique wall photosynthesis in the NY and HY populations of ZS11 and HYZ9 in 2011–2012 and 2012–2013, respectively.</p

Seed yield of ZS11 and HYZ9 in 2010–2011 and 2011–2012 growing seasons.

<p>(A) The seed yield of ZS11 and HYZ9 in 2010–2011. (B) The seed yield of ZS11 and HYZ9 in 2011–2012. The planting densities were designed as D1, 27.0×10⁴ plants ha^-1; D2, 37.5×10⁴ plants ha^-1; D3, 48.0×10⁴ plants ha^-1; D4, 58.5×10⁴ plants ha^-1; D5, 69.0×10⁴ plants ha^-1. Different lower case letters indicate significant pairwise differences between means (p<0.05; Duncan's test).</p

Sensitivity analysis for p-stat3 expression with overall survival.

<p>Sensitivity analysis for p-stat3 expression with overall survival.</p

Charateristics and results for 17 included studies.

<p>Charateristics and results for 17 included studies.</p