PhD Dissertation Defense:Muhammad Asif
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  • PhD Dissertation Defense:Muhammad Asif

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Effects of Major Global Climate Change Components on Nutritional Physiology and Biofortification of Wheat


Muhammad Asif
PhD Dissertation, 2017


Thesis Jury

Assoc. Prof. Dr. Levent Ozturk  (Thesis Advisor), Prof. Dr. Ismail Çakmak, Assoc. Prof. Dr. Emrah Kalemci, Prof. Dr. Mustafa Bülent Torun and Assist. Prof. Dr. Bahar Yildiz Kutman



Date & Time: December 18th, 2017 –  11 AM

Place: FENS-L065

Keywords : Climate change, potassium, zinc, wheat, N-forms





Increase in atmospheric carbon dioxide (CO2) concentration and drought stress are two of the important aspects of climate change. Generally, elevated CO2 increases crop biomass production and yield along with mitigating the adverse effects of drought stress. However, elevated CO2 on plants is highly dependent upon nutrients availability. Moreover, elevated CO2 is associated with decreased nutrient (Zn, Fe and protein) concentrations in vegetative tissues as well as grains. The purpose of this project was to investigate the effect of elevated CO2 on bread wheat (Triticum aestivum) as affected by nutritional amendments (K and Zn deficiencies, N-forms) and drought stress. It was found that K deficiency seriously impeded the positive effects of elevated CO2 on photosynthesis, biomass production of well-watered as well as drought stressed bread wheat plants. Moreover, plants suffering from K deficiency tended to accumulate more carbohydrates in source leaves under elevated CO2 and drought stress conditions. However, in later stages elevated CO2 partly compensates the effect of K deficiency by increasing grain yield through increasing number of spikes and thousand grain weight. Elevated CO2 ameliorated the adverse effects of Zn deficiency and drought stress on grain yield and biomass production along with seriously deteriorating the grain nutritional quality in terms of Zn and protein concentration and the effect was worst under low Zn conditions. Over all elevated CO2 decreased most of the nutrients in vegetative tissues and grains causing serious threat to human nutrition. Elevated CO2 was most effective on NH4NO3 treated plants resulting in the highest biomass enhancement ratio and optimum N and carbohydrate metabolism.