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Selecting Crop Cultivars to Maximize Yields

Reference
Thilakarathne, C.L., Tausz-Posch, S., Cane, K., Norton, R.M. Tausz, M. and Seneweera, S. 2013. Intraspecific variation in growth and yield response to elevated CO2 in wheat depends on the differences of leaf mas per unit area. Functional Plant Biology 40: 185-194.
In a study published in Functional Plant Biology, Thilakarathne et al. (2013) describe the results of a study they conducted on seven different cultivars of spring wheat (Triticum aestivum), which they grew at either ambient CO2 (384 ppm) or elevated CO2 (700 ppm) in temperature-controlled glasshouses. And what did they find?

In the case of light-saturated net photosynthesis, they found an actual stimulation provided by the extra 316 ppm of CO2 that ranged from 31% for cultivar Drysdale to 75% for cultivar Yitpi. In the case of aboveground biomass production, they also found a CO2-induced stimulation. In this case, it ranged from 0% for the cultivar H45 to 133% for cultivar Gladius. And in the case of actual grain yield, the six scientists found a CO2-induced stimulation that ranged from 0% for cultivar H45 to 98% for cultivar Gladius, with the other five cultivars sprinkled somewhere in between.

Likewise, but many years earlier, Ziska et al. (1996) had grown well watered and fertilized plants of seventeen different cultivars of rice (Oryza sativa) from seed to maturity within glasshouses maintained at atmospheric CO2 concentrations of either 373 ppm (ambient) or 664 ppm (elevated), after which they had measured both total plant biomass and grain biomass. In their case, and when the plants had been grown within a normal air temperature range, a few cultivars exhibited no significant changes in response to the specific degree of atmospheric CO2 enrichment used in their study, while the most responsive cultivar - a tropical japonica type from Brazil - exhibited a whopping 265% increase in total plant biomass and an astounding 350% increase in grain biomass.

In light of such findings, it would seem prudent for farmers to discover what cultivars of the crops they grow are most positively responsive to atmospheric CO2 enrichment under the particular growing conditions of the regions in which they are planted. Having made that determination, farmers can maximize the well-documented growth-enhancing benefits of the aerial fertilization effect of atmospheric CO2, as well as the transpiration-reducing effect that typically accompanies it and reduces the amount of water that crops would otherwise require. And doing so will allow farmers to reap greater monetary benefits both now and in the future as the CO2 concentration of the air continues to rise.

Additional Reference
Ziska, L.H., Manalo, P.A. and Ordonez, R.A. 1996. Intraspecific variation in the response of rice (Oryza sativa L.) to increased CO2 and temperature: growth and yield response of 17 cultivars. Journal of Experimental Botany 47: 1353-1359.

Archived 12 November 2013