Speaker
Description
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Introduction
Despite the significant improvements in wheat productivity achieved through breeding progress over the past few decades, there remains a pressing need to target even higher yields to fulfil the growing global demand for food. Understanding the response of both historical and modern wheat cultivars to various management strategies is crucial. This understanding can assist in breeding cultivars that demonstrate enhanced productivity and better resource efficiency across diverse environments (Voss-Fels et al., 2019). The current study aimed to evaluate the impact of agronomic practices (plant protection and growth regulators) and nitrogen application rates (0 to 240 kg N ha-1) on both the yield and yield components of historical (1895-1960) and modern (1961-2007) winter wheat cultivars released in Germany. -
Materials and methods
The study involved a field experiment over two growing seasons (2018-2019 and 2019-2020), incorporating 16 wheat cultivars released between 1895 and 2007 in Germany. The experiment evaluated three levels of nitrogen fertilizer application (0, 120, and 240 kg N ha-1) and assessed four distinct agronomic practices: chemical-free farming (CF), plant protection (PP, focusing on pest and disease control), growth regulation (GR), and a combination of PP and GR. During each growing season, the main plot consisted of 12 levels, derived from combining four agronomic practices with three nitrogen application rates. The subplots included 16 cultivars, arranged in a split-plot format within a randomized block design that comprised 12 blocks. Sowing and harvesting dates were set to October 11 and July 30 in the first, and October 15 and July 29 in the second season, respectively. The study analyzed several variables, including grain yield, yield components, harvest index, and grain nitrogen yield. -
Results
The results of the study indicated that the development of new cultivars, the application of different agronomic practices (APs), and the variation in nitrogen application rates significantly influenced both grain and grain nitrogen yields (Figure 1a). Consistent improvements in yield (+32 %), yield components (grain number, single grain weight and ear number), and harvest index (+25 %) were observed across all treatments in modern cultivars developed post-1960, compared to their historical ones (Figure 1). Grain nitrogen yield in historical cultivars was less responsive to increases in nitrogen application rates compared to modern cultivars (Figure 1a). The yield enhancement observed in modern cultivars is largely due to an increase in both the harvest index and grain number, with changes in thousand-grain weight having a smaller impact (Figure 1b). Increasing the nitrogen application rate to 120 or 240 kg N ha-1 adversely affected the yield and yield components of historical cultivars. In contrast, modern cultivars exhibited significant yield enhancement from increased nitrogen fertilization, especially when coupled with intensive agronomic practices (Figure 1). -
Discussion
The study findings showed positive trends in yield and yield components for both historical (1895-1960) and modern (1961-2007) cultivars when management was intensified. However, substantial improvements were observed only in the modern cultivars. Growth variables of historical cultivars showed more enhancement with the application of growth regulators, whereas modern cultivars exhibited greater improvements due to plant protection. Nevertheless, both types of cultivars demonstrated a synergistic response when growth regulators and plant protection were combined. The comparison between the effects of N application rates and agronomic practices (APs) revealed that the impact of N on yield and yield components was considerably greater than that of APs. This predominant influence of N application rates on long-term yield trends of various crop species has also been observed in other environments, including France (Schauberger et al., 2018).
Figure 1. The percentage change in grain and nitrogen yields across various agronomic practices and nitrogen application rates compared to the control treatment for historical (1895-1960) and modern (1961-2007) cultivars (a). The trend of harvest index, thousand grain weight, grain number, and ear number for cultivars released before and after 1960 (b). Each small gray point and large point indicate the mean of a variable per growing season and the median of cultivars across treatments.
References
Schauberger, B., et al., 2018. Yield trends, variability and stagnation analysis of major crops in France over more than a century. Scientific reports 8, 16865.
Voss-Fels, K.P., et al., 2019. Breeding improves wheat productivity under contrasting agrochemical input levels. Nature plants 5, 706–714.
| Keywords | Agronomic management; Nitrogen; Yield; Yield components; Wheat |
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