Soybean plants with fewer leaves yield more.
They attribute this boost in yield to increased photosynthesis, decreased respiration, and diversion of resources that would have been invested in more leaves than seeds.
"This rate is insufficient to fulfill the needs for global food security, where we need to produce 70-100 percent more food by 2050 to feed an estimated 9.7 billion people," said project co-lead Steve Long, Gutgsell Endowed Professor of Plant Biology and Crop Sciences at the Carl R. Woese Institute for Genomic Biology at Illinois.
If we can increase the yield of soybeans, we can solve the problems of protein demand and food production at the same time."
Published in Global Change Biology, their paper found that soybean plants produce too many leaves, most of which are shaded and inefficient, thereby wasting resources like water, carbon and nitrogen.
"The model shows that by investing less in leaves, the plant can produce more seeds," Srinivasan said.
The model predicted that a 30-40 percent decrease in leaf area would increase yields by 8-10 percent in field trials, they decreased leaf area (by manually cutting off new leaflets) by just 5 percent and still increased yields by 8 percent.
"We hypothesize that plants with fewer leaves need less water, which requires fewer roots.
Journal Reference: Venkatraman Srinivasan, Praveen Kumar, Stephen P. Long.
Decreasing, not increasing, leaf area will raise crop yields under global atmospheric change.

Wet spring leaves Kansas in a rare state: drought-free.
For only the fifth time since 2000, Kansas is entirely drought-free.
Last weekend’s blizzard, which brought more than two feet of snow to isolated areas of far western Kansas and double-digit accumulation to a narrow band that stretched north to south in the western third of the state, erased the final remnants of a drought that has been gradually receding during a remarkably wet spring.
Kansas was drought-free for three weeks last September, according to the U.S. Drought Monitor, records show.
But by the end of the year, nearly 83 percent of the state was enduring at least some degree of drought or abnormal dryness.
“Usually, parts of especially western Kansas are inherently dry anyway,” Darmofal said.
Dry conditions and strong winds set the stage for the largest single wildfire in state history in southwest Kansas in March, but steady rains and last weekend’s record-setting snow erased the nearly 15 percent of severe drought that gripped much of southwest Kansas at the beginning of the year.
Kansas and Wichita have plenty of company in avoiding dry conditions.
Philip Klotzbach, a meteorologist at Colorado State University in Fort Collins, tweeted on Friday that only 5 percent of the U.S. is currently in drought — the lowest percentage since weekly drought monitoring data began in 2000.
Stan Finger: 316-268-6437, @StanFinger

Even short-duration heat waves could lead to failure of coffee crops.
A study by OSU’s College of Forestry showed that when Coffea arabica plants were subjected to short-duration heat waves, they became unable to produce flowers and fruit.
C. arabica is the globe’s dominant coffee-plant species, accounting for 65 percent of the commercial production of the nearly 20 billion pounds of coffee consumed globally each year.
Continually producing new flushes of leaves year-round, C. arabica grows on 80 countries in four continents in the tropics.
The OSU research investigated how leaf age and heat duration affected C. arabica’s recovery from heat stress during greenhouse testing.
"This emphasizes how sensitive Coffea arabica is to temperature," said lead author Danielle Marias, a plant physiologist with OSU’s Department of Forest Ecosystems and Society.
"Heat is very stressful to the plants and is often associated with drought.
However, in regions where coffee is grown, it may not just be hotter and drier, it could be hotter and wetter, so in this research we wanted to isolate the effects of heat."
In the OSU study, C. arabica plants were exposed to heat that produced leaf temperatures of a little over 120 degrees Fahrenheit, for either 45 or 90 minutes.
"In both treatments, photosynthesis of expanding leaves recovered more slowly than in mature leaves, and stomatal conductance of expanding leaves was reduced in both heat treatments," Marias said.

EXTENSION CORNER: Drought has deeper effect on plants than wilted leaves.
Well, not that funny — but people notice it is dry when there is no rain, yet they seem to forget about it once the rain sets in.
While the rains of winter returned some water to once-dry ponds and creeks, we as gardeners and homeowners have not seen the end of the effects on our landscapes and naturalized areas.
Drought is much more than scorched grass and wilted tomato plants.
As soil moisture is pulled away from the roots, cell death in the roots and vascular tissues begins to occur.
Here’s what to expect: • Some plants will not come out of dormancy this spring.
• Some trees and shrubs that do break bud after dormancy will have root systems insufficient to support the canopy, leading to dieback or death next spring and summer.
In the case of many Leyland cypress trees, which are prone to fungal cankers, the stress of drought allows the disease to spread throughout the tree, leading to plant death.
Lastly, if you see that a tree or shrub has succumbed to disease or insects, it may be time to consider a replacement.
Donations can be dropped off at any time during the month at the Etowah County Extension Office.

"Their caterpillars defoliated 27,000 acres in Rhode Island in the spring of 2015, but even though we had winter moths everywhere last year and I saw a zillion eggs, they caused almost zero defoliation."
Faubert believes last year’s strange winter and spring weather negated what she expected to be a dire season for winter moth defoliation.
Winter moth eggs typically hatch during a warm spell in April, but last year they began hatching during a warm period in late March.
With little defoliation occurring last year from winter moths, Faubert said it’s possible that there will be fewer adult moths flying around in the next month.
"Defoliation is very stressful to trees," Faubert said.
The females crawl up tree trunks to lay their eggs.
In an experiment she conducted last year, Faubert placed two tree bands, separated by about a foot, around one tree.
One strategy Faubert is deploying to control winter moth populations is the release of a tiny parasitic fly that lays its eggs on tree leaves.
When the winter moth caterpillar consumes the eggs while eating the leaves, the eggs hatch inside the caterpillar and the fly larva eat it from the inside out.
Faubert released the flies in seven locations in Rhode Island between 2011 and 2015, and she hopes to soon see signs that it is beginning to work.