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The Positive Impact of Elevated CO2 on Sunflower Seed Production

Paper Reviewed
Pal, M., Chaturvedi, A.K., Pandey, S.K., Bahuguna, R.N., Khetarpal, S. and Anand, A. 2014. Rising atmospheric CO2 may affect oil quality and seed yield of sunflower (Helianthus annuus L.). Acta Physiologiae Plantarum 36: 2853-2861.

Writing as background for their study, Pal et al. (2014) note that sunflower is one of the world's major oilseed crops, accounting for about 14% of the world's production of seed oil, which they say "is generally considered as premium oil, because of its light color, high level of unsaturated fatty acids, lack of transfat and high oxidative stability," further noting that the crop "has potential health benefits because it contains very high concentrations of polyunsaturated fatty acids" - with more than 90% of them being linoleic and oleic acids - which they indicate are "considered good for human consumption."

As their contribution to determining how sunflower seed oil might be impacted as the air's CO2 content continues to rise, the six scientists grew two sunflower genotypes - DRSH 1 (a hybrid) and DRSF 113 (a promising variety) - under natural field conditions within open-top chambers maintained at either ambient (370 ppm) or enriched (550 ppm) atmospheric CO2 concentrations. This they did following standard agronomic practices and irrigating when needed to maintain the soil moisture level at field capacity.

Based on the results of the many measurements they made throughout the crop's growth and post-harvest, Pal et al. found that (1) the CO2-induced enhancement in photosynthesis "was 31.7-52.1% in DRSH1 and 25.5-42.8% in DRSF 113," that (2) "plants grown under elevated CO2 concentration showed 61-68% gains in biomass and 35-46% increases in seed yields of both genotypes," that (3) "oil content increased significantly in DRSF 113 (15%), that (4) "carbohydrate seed reserves increased with similar magnitudes in both the genotypes under elevated CO2 treatment (13%)," and that (5) "fatty acid composition in seed oil contained higher proportions of unsaturated fatty acids (oleic and linoleic acid) under elevated CO2 treatment," which result they say "is a desirable change in oil quality for human consumption."

Just as is found for most all food crops, the yield of sunflower seed oil is significantly enhanced by atmospheric CO2 enrichment, as is the quality of the oil.

Posted 17 February 2015