Simultaneous improvement in productivity, water use, and albedo through crop structural modification

Abstract

Spanning 15% of the global ice-free terrestrial surface, agricultural lands provide an immense and near-term opportunity to address climate change, food, and water security challenges. Through the computationally informed breeding of canopy structural traits away from those of modern cultivars, we show that solutions exist that increase productivity and water use efficiency, while increasing land-surface reflectivity to offset greenhouse gas warming. Plants have evolved to maximize capture of radiation in the upper leaves, thus shading competitors. While important for survival in the wild, this is suboptimal in monoculture crop fields for maximizing productivity and other biogeophysical services. Crop progenitors evolved over the last 25 million years in an atmosphere with less than half the [CO2] projected for 2050. By altering leaf photosynthetic rates, rising [CO2] and temperature may also alter the optimal canopy form. Here using soybean, the world's most important protein crop, as an example we show by applying optimization routines to a micrometeorological leaf canopy model linked to a steady-state model of photosynthesis, that significant gains in production, water use, and reflectivity are possible with no additional demand on resources. By modifying total canopy leaf area, its vertical profile and angular distribution, and shortwave radiation reflectivity, all traits available in most major crop germplasm collections, increases in productivity (7%) are possible with no change in water use or albedo. Alternatively, improvements in water use (13%) or albedo (34%) can likewise be made with no loss of productivity, under Corn Belt climate conditions.

Harnessing Genetic Variation in Leaf Angle to Increase Productivity of Sorghum bicolor

“…In nature, large leaf angles may have been under positive selection because shading nearby plants would reduce competitors' ability to compete for light and nutrients (Schmitt et al 2003;Drewry et al 2014). In monoculture grain cropping systems, small leaf angle has been under positive selection because this trait enables higher planting density and higher grain yield, presumably due to the benefits of improved RUE and increased nitrogen content of canopies (Drewry et al 2014;Warnasooriya and Brutnell 2014).…”

“…Smaller leaf inclination angles caused solar radiation to penetrate deeper into the canopy, and the resulting redistribution of light is predicted to increase the biomass yield potential of bioenergy sorghum by at least 3%. These results show that sorghum leaf angle is a heritable trait regulated by multiple loci and that genetic variation in leaf angle can be used to modify plant architecture to improve sorghum crop performance.KEYWORDS leaf angle; crop modeling; sorghum canopy; bioenergy sorghum; dwarf-3; P-glycoprotein; auxin transport S USTAINABLY increasing the productivity of crops on land currently used for agriculture without depleting natural resources is a global priority (Foley et al 2011;Drewry et al 2014). Improving the efficiency with which plants intercept solar radiation is one means to sustainably improve crop productivity.…”

“…KEYWORDS leaf angle; crop modeling; sorghum canopy; bioenergy sorghum; dwarf-3; P-glycoprotein; auxin transport S USTAINABLY increasing the productivity of crops on land currently used for agriculture without depleting natural resources is a global priority (Foley et al 2011;Drewry et al 2014). Improving the efficiency with which plants intercept solar radiation is one means to sustainably improve crop productivity.…”

“…Improving the efficiency with which plants intercept solar radiation is one means to sustainably improve crop productivity. Leaf angle, or leaf erectness, is a plant canopy parameter that has drawn considerable attention because of the predicted improvement in photosynthetic efficiency and reduction in plant stress afforded by the redistribution of solar radiation from upper to lower levels of canopies (Tollenaar and Wu 1999;Duvick 2005;Murchie et al 2009;Zhu et al 2010;Murchie and Reynolds 2012;Drewry et al 2014;Mansfield and Mumm 2014). Performance improvements predicted by theoretical models are corroborated by positive correlations between small leaf angles and cereal crop yields; post-green revolution rice cultivars have smaller leaf inclination angles and higher yields relative to their pre-green revolution predecessors (Yoshida 1972;Sinclair and Sheehy 1999;Sakamoto et al 2006), and modern maize is also characterized by small inclination angles as a consequence of selection for increased grain yield in breeding programs (Duvick 2005;Lee and Tollenaar 2007;Hammer et al 2009;Tian et al 2011;Mansfield and Mumm 2014).…”

Transcriptome Profiling of Tiller Buds Provides New Insights into PhyB Regulation of Tillering and Indeterminate Growth in Sorghum

“…Modeling of light interception by crop canopies indicates that current genotypes often intercept an excess of light at the top of the canopy (Zhu et al, 2010;Drewry et al, 2014). Energy sorghum hybrids tiller to a greater extent than grain sorghum genotypes, often producing canopies with excess leaf area index (greater than 7; Olson et al, 2012).…”