Speaker
Description
Yield improvement in wheat (Triticum aestivum L.) has shown signs of yield stagnation in Spain 1-4 and other countries in Europe 5–7. Furthermore, prospects for genetic gains and adaptability are challenging in the context of climate change, where the occurrence of extreme events and erratic weather difficult genotypic selection and jeopardizing genetic gains. Retrospective studies documenting physiological changes in wheat attributable to breeding can contribute to identify avenues for adaptation and selection. This study aimed to determine the physiological bases for yield differences between traditional and modern wheat cultivars of a Mediterranean region, and to quantify yield and yield-related genetic gains under contrasting growing conditions.
Three field experiments comparing 11 bread wheat cultivars (released between 1940 and 2021) representing different eras of genetic improvement in Spain were carried out during the 2022-2023 growing season. Field experiments consisted in two early sowing dates differing in water availability and location (irrigated in Lleida and rainfed in Valladolid) and a late sowing in Lleida with contrasting photothermal conditions.
Yield gains varied in magnitude and significance among environments. Gains were clear from 1940 to 2000 in the early sowing under both irrigated and rainfed conditions, while no clear gains were evidenced thereafter (Fig. 1). These gains were related to a higher number of grains per m2 and per spike rather than to spikes per m2, as well as improvements in fruiting efficiency. Harvest index has remained constant in cultivars released from 2000 whereas total biomass showed a positive linear trend for the whole period. On the other hand, there were no clear gains in the late sowing.
The absolute yield gain was much higher under irrigation than in rainfed conditions (5.5 and 2.6 g m-2 yr-1, respectively). However, yield gains estimated in relative terms (respect to the yielding condition) was the same in both conditions (c. 0.7% yr-1). The differential expression of genetic gain in absolute terms revealed a loss in yield stability with breeding and therefore yield in modern varieties was more penalised than in traditional cultivars when grown under resource-limited environments. This might be related to the fact that higher yield potential would be dependent on the responsiveness to environmental improvements.
Yield was similarly penalised due to lack of irrigation or sowing late. However, the trends changed differently depending on the source of variation. With a similar trend when the penalty was due to reduced resources, whilst the trend was lost when the penalty was due to a change in photothermal conditions.
Trends observed in grain per spike indicate a need for increased focus on enhancing total biomass and spike fertility, while considering potential trade-offs with grain size.
References
(1) Acreche, M. M.; Briceño-Félix, G.; Sánchez, J. A. M.; Slafer, G. A. Physiological Bases of Genetic Gains in Mediterranean Bread Wheat Yield in Spain. European Journal of Agronomy 2008, 28 (3), 162–170. https://doi.org/10.1016/j.eja.2007.07.001.
(2) Chairi, F.; Vergara-Diaz, O.; Vatter, T.; Aparicio, N.; Nieto-Taladriz, M. T.; Kefauver, S. C.; Bort, J.; Serret, M. D.; Araus, J. L. Post-Green Revolution Genetic Advance in Durum Wheat: The Case of Spain. Field Crops Research 2018, 228, 158–169. https://doi.org/10.1016/j.fcr.2018.09.003.
(3) Gulino, D.; Sayeras, R.; Serra, J.; Betbese, J.; Doltra, J.; Gracia-Romero, A.; Lopes, M. S. Impact of Rising Temperatures on Historical Wheat Yield, Phenology, and Grain Size in Catalonia. Frontiers in Plant Science 2023, 14.
(4) Sanchez-Garcia, M.; Royo, C.; Aparicio, N.; Martín-Sánchez, J. A.; Álvaro, F. Genetic Improvement of Bread Wheat Yield and Associated Traits in Spain during the 20th Century. The Journal of Agricultural Science 2013, 151 (1), 105–118. https://doi.org/10.1017/S0021859612000330.
(5) Brisson, N.; Gate, P.; Gouache, D.; Charmet, G.; Oury, F.-X.; Huard, F. Why Are Wheat Yields Stagnating in Europe? A Comprehensive Data Analysis for France. Field Crops Research 2010, 119 (1), 201–212. https://doi.org/10.1016/j.fcr.2010.07.012.
(6) Ray, D. K.; Ramankutty, N.; Mueller, N. D.; West, P. C.; Foley, J. A. Recent Patterns of Crop Yield Growth and Stagnation. Nat Commun 2012, 3 (1), 1293. https://doi.org/10.1038/ncomms2296.
(7) Schauberger, B.; Ben-Ari, T.; Makowski, D.; Kato, T.; Kato, H.; Ciais, P. Yield Trends, Variability and Stagnation Analysis of Major Crops in France over More than a Century. Sci Rep 2018, 8 (1), 16865. https://doi.org/10.1038/s41598-018-35351-1.
| Keywords | Triticum aestivum; Grain yield; Fruiting efficiency |
|---|
