Yield records and crop breeding strategies: reflections on the past and future perspectives
Every farmer has heard the rumours of their neighbors’ exceptionally high yields come harvest time and has learned to digest these rumours critically and skeptically. However, this year the rumours happened to be true! Statistics Canada has recently announced that this past year Quebec’s corn growers saw their biggest yields yet, weighing in at an average of 10.6 tonnes per hectare (Ménard, 2016). Amidst the excitement we may experience in the face of this agronomic achievement, it is important to take a step back and reflect on the conditions that have led us to reach these exceptional yields. Additionally, we should take the time to wonder what will be the future conditions that will drive crop improvement for years to come.
The first important thing to note is that there is not only one single driving factor that has led to these increases in yields. On the contrary, it has been a cumulative effort across multiple disciplines that has led to these significant yield performances. In fact, increased fertilizer use, more efficient chemical pesticides, large mechanical equipment and improved cultural practices such as earlier planting and narrower rows have all been attributed to some degree to being a contributor to these yield increases (Troyer and Good, 2008). However, there is one factor that seems to play a slightly more important role than some of the others. In fact, genetic improvements to corn crops have been estimated to be the cause of approximately 51% of yield increases in some regions (Qin et al., 2016).
One of the main reasons plant breeding has had such a large effect on yields is the result of breeding for increasing plant density tolerance (Qin et al., 2016). Plant density tolerance encompasses a large amount of traits that help plants in situations of high plant competition. These traits could include drought tolerance, hybrid vigour and resistance to high pest pressure. Instilling plants with these traits ensures hardy plants that will be resistant to a multitude of conditions. This is of vital importance, since in order to obtain the desired high yields at the end of the season, the plant must not only survive until the end of the season, but produce enough biomass to obtain the high yields we are looking for.
The final question is: are these increases in yields sustainable? Can we expect to see yields like this ten or twenty years into the future? Luckily for us, traits that allow plants to be tolerant to high densities also happen to make them more resilient in the face of uncertain climatic conditions. With climate change on the horizon, this is something that should not be overlooked. Nonetheless, it is also important for us to always be looking for other areas where we can be improving not only our plant breeding but also our general agronomic practices. This is especially important as we do not know today what our goals will be in the future. Perhaps in the coming years, the success of our crops will not be measured by the yields we obtain, but rather we will evaluate our performance based on our ability to produce high quality crops using low resources. In such cases, perhaps we would measure soil health or soil water quality as indicators of our performance. Whatever the future may hold, it is certain to be a challenge for the agricultural industry as a whole. However, our shared knowledge and ever improving technologies hold a lot of promise for us.
Ménard, M. 2016. Récolte record de maïs au Québec. La Terre de Chez Nous.
Qin, X., Feng, F., Li, Y., Xu, S., Siddique, K.H.M., and Liao, Y. 2016. Maize yield improvements in China: past trends and future directions. Plant Breeding. 135: 166-176.
Troyer, A.F. and Good, D. 2005. At last, another record corn crop. Journal of Crop Improvement. 14: 175-196.