An Australian study finds today’s wheat out-performs older strains in both optimum and challenging conditions
Contrary to popular opinion, modern wheat varieties are not heavily dependent on pesticides and fertilizer to remain productive.
In fact, recent research from the University of Queensland (UQ) in Australia shows that today’s wheat out-performs older strains not only in optimum conditions but under challenging growing situations. In addition, the modern wheat gene pool is rich enough to generate a 23 percent increase in yields.
The study, which was a collaboration of seven German universities along with UQ, tested 200 wheat varieties developed in Western Europe over the past 50 years.
Their performance was compared in side-by-side field trials under high, medium and low chemical input conditions. Then the varieties were studied at the Queensland Alliance for Agriculture and Food Innovation (QAAFI), a research institute at the university, to match performance differences with the varieties’ genetic make-up.
“All phenotypic evaluations were done in field trials to ensure performance assessments under realistic growing conditions,” said Kai Voss-Fels, research fellow with the university’s Centre for Animal Science and lead author of the study.
“The differences between agrochemical input levels were assessed in side-by-side comparisons at each single location, which was an enormous amount of work. This means that at each site we tested all 200 varieties in full-sized yield plots in three different treatment levels, with two replicates per variety in each treatment level.”
The study focused on varieties that played a major role in wheat production in Western Europe where grain yields are among the highest worldwide, but Voss-Fels said results can be extrapolated to other production regions because wheat breeding is similar throughout the world.
In the second part of the study, researchers obtained high-resolution genome profiles for each of the varieties from DNA marker labs and matched the differences in the genome to the performance differences observed in the field. They then developed a novel method to identify genome regions that were driving genetic gain over the course of breeding. The importance of such a large study was to clarify the long-term impacts of breeding over five decades.
“What we did consistently find was that the most recent varieties always outperformed the old ones under all investigated agrochemical input levels,” said Voss-Fels. “Actually, the difference between old and new varieties was most distinct in field trials where we did not apply any fungicides and only 50 percent of the commonly applied mineral nitrogen dosage.”
Voss-Fels said the belief that modern cultivars have lost the ability to perform well when exposed to resource-limited conditions is untrue and discounts the complex and lengthy variety registration process.
Voss-Fels said the key variables in the study were the dosages of nitrogen and chemical fungicides, both essential for high input wheat production in Western Europe.
“We applied two varying nitrogen dosages (220 kilograms of nitrogen per hectare vs 110 kg N/ha) in combination with and without chemical fungicides,” he said. “This resulted in a total of four treatment levels. We were also fortunate to have some severe water-limitation and drought at single test environments. Those sites were characterized by light and sandy soils with a lower-water-holding capacity and very little rainfall. Even there, the newest varieties performed significantly better.”
In 2018, conditions in Germany broke all drought records with 30 to 70 percent crop losses. This year is proving difficult in terms of heat and water stress. This June, Germany posted the hottest temperatures ever recorded, an indication that drought is becoming more problematic even in high-water regions. German farmers say they urgently need cultivars better adapted to drought stress.
To this end, Voss-Fels said that the information from the study could help breeders bring together the most favourable chromosome segments through cross-breeding.
“We are currently using this approach at a much larger scale in very large Australian wheat populations to develop new methodologies that optimize the selection process of parents that could be used for intercrossing in a breeding program.”
When asked whether similar observations have been made with other crops, he said long-term trends showed linear performance improvements of corn hybrids over the past 90 years under both favourable conditions with optimum water supply and environments characterized by severe droughts.
“There are large international efforts trying to understand exactly the genetic components of these parallel improvements and how we can use this knowledge to keep making significant progress in the future.”
The study, Breeding improves wheat productivity under contrasting agrochemical input levels, was published in Nature Plants.