Impact of fertilization, crop protection and growth regulators on growth and yield of old and modern winter wheat cultivars
Study in collaboration with University of Bonn
In a long-term fertilization experiment at the University of Bonn (Dikopshof), a continuous increase in grain yields of winter wheat during the 20th and early 21st century from about 2 to 10 t/ha was observed for plots with good nutrient supply. However, when the wheat varieties that ever have been grown in the experiment were cultivated in parallel, even very old cultivars achieved high yields of up to 10 t/ha with small differences to yields of modern cultivars. This means that breeding progress was not the main factor contributing to the observed historical yield increase. But what was it then? In a field trial carried out by the Division of Agronomy at the University of Göttingen, the impact of crop protection, growth regulators and fertilization on grain yields of old and new cultivars were investigated.The field trial was established with 16 winter wheat cultivars released in Germany between 1895 and 2007 and grown before at the long-term experiment Dikopshof. Objective is to test the impact of the factors fertilization, crop protection and growth regulators on crop yield but also on other variables. The following factors and factor levels are tested:
| # | Factor | Factor levels |
|---|---|---|
| 1 | Cultivar | 16 cultivars released in period 1895-2007 |
| 2 | Fertilization | 3 levels (zero, intermediate, high) |
| 3 | Crop protection | 2 levels (with, without) |
| 4 | Growth regulators | 2 levels (with, without) |
The 192 plots are arranged in a randomized block design with 12 blocks. The 16 cultivars are grown in each of the 12 blocks.
In order to answer the research questions, numerous parameters were measured or observed in the two years of the field experiment. The most important results were published in year 2024 in European Journal of Agronomy. We found positive trends in the yield and yield components for both historical (1895–1960) and modern (1961–2007) cultivars; however, significance was only noted for modern cultivars. It was found that when comparing N supply and agronomic practises, N application had a distinctly greater impact on yield and yield components than other treatments for all cultivars. Crop growth in historical cultivars was supported more by growth regulators, while modern cultivars gained more benefits from plant protection. However, both categories of cultivars produced a synergistic response when combining agronomic practices. In both historical and modern cultivars, grain number per ear was the most influential contributing factor to yield. Nevertheless, the effect of the thousand grain weight on yield was notably less for modern cultivars compared to their historical ones.
The comprehensive and systematic data analysis performed to obtain the major results was supported by a number of thesis projects of master and bachelor students. For example, bachelor theses investigated the effect of the use of crop protection and growth regulators on the grain yield of old and new wheat cultivars. The architecture of the plants and plant stands was also studied, e.g. how the number, height and position of the leaves in wheat cultivars differ among the wheat cultivars and how the light interception and radiation use efficiency are affected. Previous studies on the phenology of the different wheat cultivars have shown that the flowering of modern cultivars is up to two weeks earlier than flowering of old cultivars. Therefore another focus was on the cultivar differences in crop phenology. Master's theses projects were also performed for various topics. For example, it was examined whether old and modern wheat cultivars differ in terms of root development. The effects of fertilization and the use of growth regulators was also taken into account. Furthermore the impact of the wheat cultivars (old vs. modern) as well as the use of growth regulators on the greenhouse gas emissions was examined. Other topics proposed for theses can be found in the "Teaching" section of our website.
Members of the agronomy division involved in the study
Prof. Dr. Stefan SiebertDr. Ana Meijide
Christiane Münter
Former staff members:
Katharina Hey (responsible)
Dr. Hamideh Nouri
Dr. Ehsan Eyshi Rezaei