Author
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Bruns, Herbert |
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Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/28/2018 Publication Date: 3/1/2019 Citation: Bruns, H.A. 2019. Comparison of yield, yield components and physiological parameters of drought tolerant and conventional corn hybrids. Agronomy Journal. 111(2):1-7. https://doi.org/10.2134/agronj2018.01.0047. DOI: https://doi.org/10.2134/agronj2018.01.0047 Interpretive Summary: Corn hybrids are now available with some genetic tolerance to drought stress. A scientist with the USDA-ARS Crop Production Research Unit at Stoneville, MS compared the performance and physiology of three such hybrids to three conventional ones grown with and without irrigation, in a three year experiment. Differences in grain yields occurred each year but no particular hybrid, group of hybrids (drought tolerant vs. conventional) nor irrigated vs. non-irrigated treatments were consistently superior or inferior in yield. No differences were observed in most of the physiological processes measured except the rate of water loss through the leaves (transpiration) was higher at pollination than later on during kernel filling. Intrinsic water use efficiency (IWUE), the ratio of photosynthesis rates to air and water vapor exchange rates through the leaves (stomatal conductance), was 1:1 at about half of full light, similar to what was earlier observed in grain sorghum. The drought tolerant hybrids, grown under the available moisture in this experiment did not demonstrate any yield or physiological advantages over conventional hybrids. Technical Abstract: Corn (Zea mays L.) consumes large quantities of water to produce yield and is partially responsible for depleting underground aquafers. Six hybrids, three genetically engineered for drought tolerance were evaluated for yield, yield components and physiological parameters of A, gs, Em, Ci and IWUE during early reproductive growth in 2014 through 2016 with irrigated and non-irrigated treatments. Irrigation did not improve yields any year and among any hybrids. Hybrid differences in yield occurred each year but no consistency across years were observed and genetically drought tolerant hybrids were not always superior. Mean yields in 2016 (12,590 kg ha-1) > 2015 (10,214 kg ha-1) 2014(7843 kg ha-1). Low yields in 2014 are attributed to fewer kernels per plant due to possible formesafen herbicide application to soybean (Glycine max L. Merr.) the previous year. Of the physiological parameters measured (A, gs, Em, Ci and IWUE) only Em was found to be greater at anthesis (R1) than at kernel filling (R2) and irrigated treatments were greater than non-irrigated. The ratio of A:gs/100 (IWUE) was found to be 1.0 at ~ 1200 IPAR (indicated photosynthetically actively radiation), similar to previous data on a C4 species. |
