US researchers find corn hybrids with high yields come with more variability

The agriculture industry is challenged with feeding a growing population while minimising its environmental footprint. For corn breeders, this means improving nitrogen-use efficiency and crowding tolerance, all while maximising yield.

A new study from the University of Illinois affirms that the first step is understanding the genetic yield potential of current hybrids.

Fred Below, professor of crop physiology in the Department of Crop Sciences at the university and co-author on the study, says growers and breeding programmes need to understand which hybrids have stable yields across environments or are able to produce greater yields with more fertiliser and higher plant populations.

A hybrid with high-yield stability is less responsive to the environment — it will perform consistently in sub-optimal and optimal conditions.

It’s a workhorse – dependable, but not flashy, Professor Below says.

“Alternatively, a hybrid with high adaptability will yield like gangbusters when planted in optimal conditions, but may let farmers down in a bad year. It’s more like a racehorse: it’ll go, but it’s finicky,” he says.

The problem is that current commercial breeding programmes develop their elite hybrids under optimal conditions — high levels of nitrogen fertiliser and plenty of space between rows — and only test yield responses to different crop-management practices at the pre-commercial stage. This means there is a limited understanding of each hybrid’s stability and adaptability under variable conditions.

To fill the gap, Professor Below and his team evaluated 101 commercially available elite hybrids at two planting densities and three nitrogen fertiliser rates across several years and locations.

“The objective was to measure the interactions of the hybrid with the environment and management style by evaluating an extensive assortment of current maize hybrids for yields and classify them for yield stability and crop-management adaptability to improve future breeding programs,” he says.

The researchers found the amount of applied nitrogen fertiliser had a much greater effect on yield than planting density, but they emphasise that the consistency of the yield response was more important.

Hybrids that combined above-average yield under unfertilized and low-nitrogen conditions exhibited more consistent yields regardless of the environment, even when grown with high rates of nitrogen. These workhorse hybrids would be best used in nitrogen-loss prone areas, or when yield stability is more desired.

In contrast, other hybrids yielded more under high-nitrogen than low-nitrogen conditions, but their yields were more variable, due to a greater sensitivity to environmental conditions. These racehorse hybrids have potential for greater yield return when provided the optimal management and environment, but also carry a higher risk of underperformance in yield when faced with less-than-ideal conditions.

“Selecting hybrids with both high yields and yield stability may be challenging, since yield levels under lower nitrogen availability and yield increases with high nitrogen fertilization were negatively correlated,” Below says.

Hybrids that are adaptable to high plant density and nitrogen conditions exhibited greater yield potential, but also greater yield variation.

Journal Reference:

  1. Adriano T. Mastrodomenico, Jason W. Haegele, Juliann R. Seebauer, Frederick E. Below. Yield Stability Differs in Commercial Maize Hybrids in Response to Changes in Plant Density, Nitrogen Fertility, and EnvironmentCrop Science, 2018; 58 (1): 230 DOI: 10.2135/cropsci2017.06.0340

Source: ScienceDaily


Finding alternatives to herbicides: early-killed rye shows promise in edamame

With the rise of herbicide-resistant weeds in most grain and vegetable crops, American farmers are looking for alternatives to herbicides to control weeds.

Cover crops offer one potential weed management tool. Their use in specialty crops is limited, and no testing has been done so far in edamame.

But a new University of Illinois study (see here) reports that early-killed cereal rye shows promise for edamame growers.

“Early-killed rye reduced weed density by 20 per cent and suppressed early-season weed growth 85 percent,” says Marty Williams, an ecologist with the Department of Crop Sciences at U of I and the USDA Agricultural Research Service.

Edamame is notoriously hard to get started. The soybean variety’s large seeds make them good for eating — edamame seeds are consumed at an immature stage, when they’re firm and green — but the crop can suffer from low seedling emergence in the field.

Williams wasn’t sure that asking them to struggle through a layer of cover crop residue would work.

“The question was: Can we find a cover crop management system that provides some amount of weed suppression without causing a problem for the crop? Edamame is far more sensitive to soil conditions during emergence than grain-type soybean,” he says.


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Global warming could cause key culinary crops to release seeds prematurely

British researchers show that higher temperatures accelerate seed dispersal in crop species belonging to the cabbage and mustard plant family, limiting reproductive success.

This effect is mediated by a gene called INDEHISCENT. The findings appear this week in the journal Molecular Plant.

“In many crops, such as oilseed rape, premature seed dispersal is one of the major causes of crop loss. In the context of climate change, this could become increasingly severe,” says co-senior author Vinod Kumar, a plant developmental biologist at the John Innes Centre in Norwich, England.

“This study exposes the potential vulnerabilities of crop production in the warming world and paves the way for addressing this problem.”

Plants have an extraordinary ability to adjust their life cycle to suit a range of environmental conditions. For example, despite day-to-day changes in weather and temperature, the release of seeds stays in tune with prevailing seasonal conditions.

“Seed dispersal is also a key trait that must be controlled when domesticating plants for food production,” says co-senior author Lars Østergaard, a plant geneticist at the John Innes Centre.

“With the prospect of climate change affecting crop performance, we wanted to understand how environmental signals such as temperature affect seed dispersal.”

One clue came from the observation that Arabidopsis plants, which belong to the Brassicaceae (mustard or cabbage) family, mature and open their seed pods faster when grown at elevated temperatures. Inspired by this observation, Xin-Ran Li, a postdoctoral researcher with Kumar and Østergaard and first author of the study, set out to investigate.

They found a rise in temperature, from 22ºC to 27ºC, accelerated pod shattering and seed dispersal in Arabidopsis plants and important Brassicaceae crops such as oilseed rape, a key ingredient in vegetable oil. Moreover, elevated temperatures accelerated seed dispersal by enhancing the expression of the INDEHISCENT gene, which is known to regulate the development of seed pod tissue and promote fruit opening.

“We speculate that such mechanisms have evolved to facilitate proper seasonal timing of dispersal to ensure that seeds are released under conditions that are both timely and climatically optimal for germination,” Li says. “There could perhaps be a selective advantage in early maturation and dispersal in the wild.”

Beyond the evolutionary implications, the findings could have broad relevance for maintaining yields of important crops. Oilseed rape is one of the largest sources of vegetable oil in the world and is also used for biofuel and animal feed.

More generally, the Brassicaceae family includes many economically valuable agricultural crops, including cabbage, mustard, broccoli, cauliflower, collard greens, Brussels sprouts, bok choy, kale, turnip, radish, and rutabaga.

“We were excited by the discovery that what we found in the model plant Arabidopsis also holds true for both crop plants, such as oilseed rape, as well as non-domesticated species from the Brassicaceae family,” Kumar says. “This highlights the significance of our findings both in the wild as well as in the field.”

Based on their study, the research team suggests new strategies for preparing crops for global warming. For example, plant breeding efforts could focus on developing temperature-resilient varieties capable of coping with climate change. Moreover, gene-editing tools, such as the CRISPR/Cas system, could be used to reduce the expression of the INDEHISCENT gene, thereby delaying seed release and reducing crop loss.

For their own part, Kumar and Østergaard plan to further investigate the molecular mechanisms underlying temperature-induced changes in seed dispersal.

They hope that by understanding this in detail, they will be better equipped to devise strategies to breed for crop resilience to climate change.

US scientists develop new tool to predict climate change effects on crop yields

University of Illinois researchers are attempting to bridge two types of computational crop models to become more reliable predictors of crop production in the American Corn Belt.

One class of crop models is agronomy-based; the other is embedded in climate models or earth system models.

They are developed for different purposes and applied at different scales, says Kaiyu Guan, an environmental scientist and the principal investigator on the research.

“Because each has its own strengths and weaknesses, our simple idea is to combine the strengths of both types of models to make a new crop model with improved prediction performance.”

Guan and his research team implemented and evaluated a new maize growth model, represented as the CLM-APSIM model, by combining superior features in both Community Land Model (CLM) and Agricultural Production Systems sIMulator (APSIM).

“The original maize model in CLM only has three phenological stages, or life cycles. Some important developmental stages such as flowering are missing, making it impossible to apply some critical stresses, such as water stress or high temperature at these specific developmental stages,” says Bin Peng, a postdoctoral researcher in Guan’s lab and also the lead author.

“Our solution is incorporating the life cycle development scheme of APSIM, which has 12 stages, into the CLM model. Through this integration, stresses induced by high temperature, soil water and nitrogen deficits, can be taken into account in the new model.”

Peng says they chose CLM as the hosting framework to implement the new model because it is more process-based and can be coupled with climate models.

“This is important as the new tool can be used to investigate the two-way feedback between an agroecosystem and a climate system in our future studies.”

As well as replacing the original maize phenology model in CLM with that from the APSIM model, the researchers have made several other innovative improvements in the new model. A new carbon allocation scheme and a grain number simulation scheme were added, as well as a refinement to the original canopy structure scheme.

“The most alluring improvement is that our new model is closer to getting the right yield with the right mechanism,” says Guan.

“The original CLM model underestimates above-ground biomass but overestimates the harvest index of maize, leading to apparent right-yield simulation with the wrong mechanism. Our new model corrected this deficiency in the original CLM model.”

Peng says the phenology scheme of APSIM is quite generic.

“We can easily extend our new model to simulate the growth processes of other staple crops, such as soybeans and wheat. This is definitely in our plan and we are already working on it.

“All the work was conducted on Blue Waters, a powerful petascale supercomputer at the National Center for Supercomputing Applications (NCSA) on the University of Illinois campus,” says Peng. “We are currently working on parameter sensitivity analysis and Bayesian calibration of this new model and also on a high resolution regional simulation over the U.S. Corn Belt, all of which would not be possible without the precious computational resources provided by Blue Waters.”

The study, “Improving maize growth processes in the community land model: Implementation and evaluation,” is published (HERE) in Agricultural and Forest Meteorology.

Scientists remove reliance on seasonality in new lines of broccoli

Scientists at the John Innes Centre in Norwich are developing a new line of fast-growing sprouting broccoli that goes from seed to harvest in eight to 10 weeks. It has the potential to deliver two full crops a season in-field or it can be grown all year round in protected conditions, which could help with continuity of supply when growers are no longer reliant on seasonal weather conditions.

This innovation in crop production builds on the wealth of fundamental research carried out by Professor Dame Caroline Dean and her lab on vernalisation — the need for some plants to experience a period of cold weather before they can flower. The timing of the switch to flowering is critical for a plant’s adaptation to the environment and its resulting yield.

A press release from the centre (HERE) says a team led by working collaboratively with Professor Dean, have focused on translating this knowledge to Brassica crop species.

Many crops rely on this period of cold before they can flower and so are very susceptible to fluctuating winter temperatures.

Recent adverse weather in Murcia, Spain, led to a shortage of courgettes, iceberg lettuce and broccoli. The team at the John Innes Centre has been working on way to increase crop productivity and reduce vulnerability to fluctuations in climate.

Dr Irwin said, “We harnessed our knowledge of how plants regulate the flowering process to remove the requirement for a period of cold temperature and bring this new broccoli line to harvest faster. This means growers could turn around two field-based crops in one season, or if the broccoli is grown in protected conditions, 4-5 crops in a year.”

This line has been developed with strategic funding from the Biotechnology and Biological Sciences Research Council. The John Innes Centre aims to provide pre-breeding material to plant breeders and growers for year-round scheduling of Brassica vegetables.

The new broccoli line developed at the centre is one of a number that have been selected as a step toward climate-proofing our crops.Dr Irwin said the development has the potential to remove growers’ exposure to seasonal weather fluctuations from crop production. This could mean broccoli — and in future other vegetables where the flower is eaten, such as cauliflowers — can be grown anywhere at any time enabling continuous production and supply of fresh local produce.

Judith and her team were surprised to see how rapidly plants grew from seed to harvestable sprouting broccoli spears. Detailed analysis identified the gene responsible for this trait. They are now testing further generations under conventional glasshouse and controlled environment conditions. This line has been developed using conventional breeding techniques.

The next steps from experimental line to commercialisation involve flavour and nutritional analysis and performance testing under true protected and field commercial growing conditions.

Big future predicted for bright-skinned White Beauty potato

A new bright-skinned potato, called White Beauty, has been produced from a 15-year breeding programme at Plant & Food Research. It is a cross between the disease-resistant Summer Delight potato and the old multipurpose Australian favourite Coliban.

The result is a bright, versatile potato described as extremely high-yielding.

“White Beauty comes with a lot of promise,” says Plant & Food Research crop scientist John Anderson.

“Not only is it showing itself to be an excellent all-round cooking potato, it has a very nice taste, which we think will prove a real challenge to other potato cultivars in the market.”

White Beauty has a lower sugar and higher dry matter content than many other potatoes in the fresh market potato range, such as Nadine, the most widely consumed white potato. This means it makes a good mash and is great for roasting, as well as being delicious boiled whole, making it a more versatile potato for consumers.

Although marketed as White Beauty, the cultivar name is”Crop39″ and is licensed to Morgan Laurenson Ltd.

The company believes the impressive characteristics of the new cultivar should translate well into wide distribution.

“White Beauty is set to become a serious market contender in the washed and brushed table potato range,” says Morgan Laurenson Managing Director Bill Foster. “From the perspective of both the grower and the consumer, we believe White Beauty has the potential to be a hit.

“The characteristics of White Beauty also bode well for exploring new export opportunities,” says Mr Foster.

Although White Beauty has been bred specifically for New Zealand conditions, it is being evaluated in both Australia and the USA.

It will be commercially available to growers through Morgan Laurenson Ltd from 2017.

Climate change will require land-use change to keep up with global food demand, study finds

A study led by researchers from the University of Birmingham shows that much of the land now used to grow wheat, maize and rice is vulnerable to the effects of climate team.

Without significant improvements in technology, global crop yields are likely to fall in the main growing areas and production will be forced to move to new areas.

The world population is projected to top nine billion in the next 30 years. The amount of food produced globally to feed them must double.

The study says the effects of climate change could lead to a major drop in productivity in the main growing areas by 2050, along with a corresponding increase in potential productivity of many previously-unused areas, pointing to a major shift in the map of global food production.

Published this month in Nature Communications, the study uses a new approach combining standard climate change models with maximum land productivity data, to predict how the potential productivity of cropland is likely to change over the next 50-100 years as a result of climate change.

The results show:

  • Nearly half of all maize produced in the world (43%), and a third of all wheat and rice (33% and 37% respectively), is grown in areas vulnerable to the effects of climate change.
  • Croplands in tropical areas, including Sub-Saharan Africa, South America and the Eastern US, are likely to experience the most drastic reductions in their potential to grow these crops
  • Croplands in temperate areas, including western and central Russia and central Canada, are likely to experience an increase in yield potential, leading to many new opportunities for agriculture

While the effects of climate change are usually expected to be greatest in the world’s poorest areas, this study suggests that developed countries may be equally affected.

Efforts to increase food production usually focus on closing the yield gap, which means minimising the difference between what could potentially be grown on a given area of land and what is actually harvested. Highly developed countries already have a very small yield gap, so the negative effects of climate change on potential yield are likely to be felt more acutely in these areas.

“Our model shows that on many areas of land currently used to grow crops, the potential to improve yields is greatly decreased as a result of the effects of climate change,” says lead researcher and University of Birmingham academic Dr Tom Pugh.

“But it raises an interesting opportunity for some countries in temperate areas, where the suitability of climate to grow these major crops is likely to increase over the same time period.”

The political, social and cultural effects of these major changes to the distribution of global cropland would be profound, as currently productive regions become net importers and vice versa.

But climate is just one factor when looking at the future of global agricultural practices, Pugh said.

Local factors such as soil quality and water availability also have a significant effect on crop yields in real terms.

Production of the world’s three major cereal crops nevertheless must keep up with demand. If this can’t be done  by making existing land more efficient, the only other option is to increase the amount of land that is used.