Most corn growers immediately notice that increased nighttime temperatures throughout grain fill seemingly knock a number of bushels off potential yield. Warmth stress in the course of the day can do the identical factor.
That’s why the late Jim Newman, a Purdue College ag meteorologist, held to the idea that cooler summers with enough however not extreme moisture usually resulted in years when USDA corn yield estimates would rise from August via January. These years favored corn packing in additional bushels throughout grain fill, and USDA formulation would often underestimate yield. Conversely, if it was a sizzling, dry summer season, he theorized that USDA would drop yield estimates from the preliminary August estimate.
Newman primarily based his conclusions on observations from 1960 via the early Eighties. It’s unclear if anybody has examined the idea since then.
Greater temps damage
Syngenta issued the Golden Harvest Agronomy in Motion 2021 Analysis Assessment earlier this 12 months. David Schlake, Golden Harvest west agronomy supervisor, and Steve Wilkens, Golden Harvest east agronomy supervisor, wrote the introduction to this 160-page assessment.
“Evening Temperature Affect on Corn Grain Fill Interval and Yield Potential” concluded that night time temperatures play an vital position in maximizing grain fill potential. Historic information exhibits a 2.8- to 4.7-bushel-per-acre yield decline for each 1 diploma enhance in July and August common night time temperatures.
Nevertheless, each night time and day temperatures can independently affect yield potential.
You may’t management temperature, however you’ll be able to assist keep a disease-free higher cover and guarantee late-season nutrient availability. If you happen to irrigate, you’ll be able to management moisture.
What’s the magic nighttime temperature? The authors of the Golden Harvest article counsel it shouldn’t exceed 70 levels F. Yield loss plotted in opposition to common minimal nighttime temps signifies loss could start earlier than the nighttime minimal reaches 70 levels. That’s primarily based on information collected from 1956 via 2019 on the county stage by the Nationwide Agricultural Statistics Service and the Nationwide Oceanic and Atmospheric Administration. The development line for yield loss is sharper, from a minimal of 65 to 70 levels, for information from Kansas and Missouri, however the development can be towards yield loss, particularly from 65 to 70 levels as an evening minimal, primarily based on date from Iowa, Illinois and Indiana.
Earlier analysis
Maybe essentially the most telling proof is from an article printed within the Canadian Journal of Plant Science, Quantity 63, in 1983. Controlling temperatures, researchers arrange 4 environments: 77 levels in the course of the day and 59 levels at night time; 77 day and night time; 95 day and 59 night time; and 95 day and 77 night time. Grain ear weight was highest for the primary therapy, second highest for 77 and 77, and lowest when daytime temp was 95. Nevertheless, there was no vital distinction for ear weight when the daytime temp was 95 and it was both 59 or 77 at night time. Kernel dimension adopted a really related sample.
Maybe the shock was that the grain fill interval from silking to black layer was 57 days for the good therapy, 49 days for cool days and heat nights, 42 days for decent days and funky nights, and 39 days for heat days and heat nights.
One idea holds that increased night time temps enhance respiration, affecting yield. The opposite, illustrated within the 1983 trial, says elevated warmth shortens grain fill, lowering yield.
