TECHNISCHE UNIVERSITÄT MÜNCHEN Lehrstuhl für Pflanzenernährung Modeling of growth and yield of some wheat cultivars under water shortage and expected climate change Mona Mohamed Ahmed Mohamed Maze Vollständiger Abdruck der von der Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt der Technischen Universität München zur Erlangung des akademischen Grades eines Doktors der Agrarwissenschaften genehmigten Dissertation. Vorsitzender: Univ.-Prof. Dr. J. Ch. Munch Prüfer der Dissertation: 1. Univ.-Prof. Dr. U. Schmidhalter 2. Priv.-Doz. Dr. E. Priesack (Georg-August-Universität Göttingen) Die Dissertation wurde am 21.08.2012 bei der Technischen Universität München eingereicht und durch die Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt am 15.10.2012 angenommen. Acknowledgment It would not have been possible to write this doctoral thesis without the help and support of the kind people around me, to only some of whom it is possible to give particular mention here. Above all, thank ALLAH for giving me courage and support in order to accomplish the task of my thesis. I am truly indebted and thankful to my great family. My parents, brother and sisters have given me their unequivocal support throughout, as always, for which my mere expression of thanks likewise does not suffice. This dissertation would not have been possible without the help, support and patience of my principal supervisor, Prof. Dr. Urs Schmidhalter, not to mention his advice and unsurpassed knowledge of his research area. The good advice, support and friendship of my second supervisor, PD Dr. Eckart Priesack, has been invaluable on both an academic and a personal level, for which I am extremely grateful. I would like to acknowledge the financial, academic and technical support of the Technische Universität München – Weihenstephan and “Chancengleichheit für Frauen in Forschung und Lehre” scholarship. The library facilities and computer facilities of the University has been indispensable. I also thank the DAAD (Deutscher Akademischer Austausch Dienst) scholarship with the Egyptian government for their financial support of my research at the first two years. I am obliged to all my colleagues in the chair of Plant Nutrition – Weihenstephan, who supported me a lot not only on the academic level but also on the personal one, with the deepest gratitude. I am truly indebted and thankful to the Modelling Soil-Plant-Atmosphere Systems team, Institute of Soil Ecology, Helmholtz Zentrum München for their valuable support. I owe sincere and earnest thankfulness to Dr. Harald Maier at the Deutscher Wetterdienst – Weihenstephan for providing me with the future weather information. I would like to thank to the Cairo University and Prof. Ahmed Hegazy the Head of Ecology Division, Faculty of Science, and also the Central Laboratory for Agricultural Climate – Agricultural Research Center. I would like to show my sincere gratitude to Prof. Mahmoud Medany, the Professor of agrometeorology, who guides me always at the beginning of my research career. It is great pleasure to thank all my friends and colleagues who helped me write my dissertation successfully. Last, but by no means least, I dedicate my research to my first homeland Egypt and my second homeland Germany, and I wish the thesis to be valuable and useful to the scientific research. Table of Contents List of Tables ........................................................................................................................... IV List of Figures ........................................................................................................................... V List of Maps ........................................................................................................................... VII List of Photos ........................................................................................................................ VIII List of abbreviations and symbols ........................................................................................... IX 1 Introduction ........................................................................................................................ 1 1.1 The affected factors on wheat growth ......................................................................... 1 1.2 Temperature effect on winter wheat ............................................................................ 1 1.3 Temperature and phenological development .............................................................. 2 1.4 Lethal temperatures ..................................................................................................... 3 1.4.1 Hot episodes effect on winter wheat .................................................................... 3 1.4.2 Freezing effect on wheat ...................................................................................... 5 1.5 Solar radiation and precipitation role in wheat growth ............................................... 7 1.6 Wheat growth related to the different soil attributes ................................................... 8 1.7 The expected climate change effect on wheat crop ..................................................... 9 1.8 The effect of the expected temperature increase on wheat growth ............................. 9 1.9 The direct effect of the expected increase of CO2 ..................................................... 10 1.10 Wheat crop models ................................................................................................ 12 1.11 Climate prediction ................................................................................................. 15 2 Materials and Methods ..................................................................................................... 17 2.1 Experimental data set ................................................................................................ 17 2.2 The methodology of the wheat crop model ............................................................... 19 2.3 Evapotranspiration and Soil Water Flow .................................................................. 19 2.3.1 Potential Evapotranspiration .............................................................................. 19 2.3.2 Actual Transpiration .......................................................................................... 20 I 2.3.3 Soil water flow ................................................................................................... 21 2.4 Plant Growth ............................................................................................................. 24 2.4.1 Phenological Development ................................................................................ 24 2.4.2 Crop Growth ...................................................................................................... 25 2.4.3 Environmental Factors ....................................................................................... 26 2.4.4 Partitioning to Crop Organs ............................................................................... 27 2.5 Model calibration ...................................................................................................... 28 2.6 Model validation ....................................................................................................... 29 2.7 Model efficiency ....................................................................................................... 29 2.8 Future weather data ................................................................................................... 30 2.9 The expected future geographical distribution of yield ............................................ 31 3 Results .............................................................................................................................. 33 3.1 Model efficiency ....................................................................................................... 33 3.2 The simulated biomass partitioning .......................................................................... 41 3.3 Soil water content sensitivity analysis ...................................................................... 49 3.4 Scenario simulation based on climate projection for 2021-2100 .............................. 50 3.5 Spatial yield distribution in Bavaria .......................................................................... 74 3.6 The computer-based model description .................................................................... 83 4 Discussion ........................................................................................................................ 91 4.1 Temperature and phenological development ............................................................ 91 4.1.1 Cardinal temperature for the developmental stages ........................................... 91 4.1.2 Growing degree days for the developmental stages .......................................... 92 4.2 Extreme temperature effect on the growth ................................................................ 95 4.2.1 The effect of hot episodes .................................................................................. 95 4.2.2 Freezing effect ................................................................................................... 97 4.3 Water deficiency effect on the growth ...................................................................... 99 4.4 The dry matter allocation