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Crop Breeding for High Production, Water Use Efficiency & Albedo
Volume 17, Number 36: 3 September 2014

In an intriguing paper published in Global Change Biology, Drewry et al. (2014) write that the "global demand for the major grain and seed crops is beginning to outstrip production for the first time in more than four decades, complicating decisions at the intersection of food security, water use and climate change mitigation," while further noting that (1) "trends in population growth and the expansion of the middle class globally have driven calls for a near doubling of food production by the middle of the century," but that (2) "yield gains for the major food crops have stagnated, and at present rates of improvement, this doubling will not be achieved," citing Long and Ort (2010).

So what could mankind possibly do to successfully deal with this unfortunate situation?

Four years earlier, Drewry et al. (2010a,b) had already demonstrated that "the structural traits of modern soybean cultivars are suboptimal for productivity," and they went on to investigate, as they describe it, whether crop canopies could be architecturally redesigned to "simultaneously achieve maximization of CO2 uptake, minimization of water use, and maximization of total shortwave albedo," the latter of which accomplishments - if achieved - could help to mitigate any concurrent global warming that might be occurring. And in this regard, they also note that "mutants for leaf erectness have been identified for crops, including rice (Sakamoto et al., 2006; Zhao et al., 2010) and wheat (Tanner et al., 1966; De Carvalho and Qualset, 1978), and have been shown to significantly increase yield when plant spacing is also considered." In addition, they note that "genetic approaches to improving plant water use and leaf gas exchange properties are now being developed," citing Masle et al. (2005) and Dodd et al. (2011). And we would also note that atmospheric CO2 enrichment itself improves these two important plant functions, i.e., plant water use efficiency and biomass production.

And so it was that Drewry et al. (2014) conducted yet another set of numerical experiments that did indeed demonstrate, as they describe it, that "computationally informed breeding of canopy structural gains in productivity, water use and albedo can all be achieved." And if there happened to be a significant impetus for earth's surficial air temperature to rise in response to the ongoing anthropogenic-induced enrichment of the air with CO2, these same genetically-induced changes in crop canopy architecture would likely negate it.

Sherwood, Keith and Craig Idso

References
De Carvalho, F.I. and Qualset, C. 1978. Genetic variation for canopy architecture and its use in wheat breeding. Crop Science 18: 561-567.

Dodd, I.C., Whalley, W.R., Ober, E.S. and Parry, M.A.J. 2011. Genetic and management approaches to boost UK wheat yields by ameliorating water deficits. Journal of Experimental Botany 62: 5241-5248.

Drewry, D., Kumar, P. and Long, S.P. 2014. Simultaneous improvement in productivity, water use, and albedo through crop structural modification. Global Change Biology 20: 1955-1967.

Drewry, D., Kumar, P., Long, S.P., Bernacchi, C., Liang, X.-Z. and Sivapalan, M. 2010a. Ecohydrological responses of dense canopies to environmental variability: 1. Interplay between vertical structure and photosynthetic pathway. Journal of Geophysical Research 115: 10.1029/2010JG001340.

Drewry, D., Kumar, P., Long, S.P., Bernacchi, C., Liang, X.-Z. and Sivapalan, M. 2010b. Ecohydrological responses of dense canopies to environmental variability: 2. Role of acclimation under elevated CO2. Journal of Geophysical Research 115: 10.1029/2010JG001341.

Long, S.P. and Ort, D.R. 2010. Moe than taking the heat: crops and global change. Current Opinion in Plant Biology 13: 240-247.

Masle, J., Gilmore, S.R. and Farquhar, G.D. 2005. The ERECTA gene regulates plant transpiration efficiency in Arabidopsis. Nature 436: 866-870.

Sakamoto, T., Morinaka, Y., Ohnishi, T. et al. 2006. Erect leaves caused by brassinosteroid deficiency increase biomass production and grain yield in rice. Nature Biotechnology 24: 105-109.

Tanner, J., Gardener, C., Stoskopf, N. and Reinbergs, K. 1966. Some observations on upright-leaf-type small grains. Canadian Journal of Plant Science 46: 690.

Zhao, S.-Q., Hu, J., Guo, L.-B., Qian, Q. and Xue, H.-W. 2010. Rice leaf inclination 2, a VIN3-like protein, regulates leaf angle through modulating cell division of the collar. Cell Research 20: 935-947.