Factors Affecting Wheat Germination and Stand Establishment in Hot Soils
Hot soil conditions at sowing also reduce coleoptile length. The coleoptile is a rigid, protective structure that covers the emerging shoot to aid it in reaching the soil surface. Once the coleoptile breaks the soil surface, it stops grow¬ing and the first true leaf emerges. If the coleoptile does not emerge through the soil surface, the first true leaf emerges below ground, takes on an accordion-like appearance, and the wheat plant typically dies.
For this reason, wheat should never be sown deeper than the coleoptile length. Wheat coleoptile length is related to mature plant height, and most modern, semi-dwarf varieties have shorter coleoptiles than old, tall varieties. Most modern wheat varieties can safely be sown at a one-inch depth, but many will not emerge when sown deeper than one inch into hot soils. For this reason, “dusting in” early-sown wheat and waiting on a cool rain to reduce high-temperature germination sensitivity and increase coleoptile length frequently results in more uniform emergence than planting deeper to reach moisture.
Coleoptile length evaluation is performed in Bozeman under growth chamber conditions. Long coleoptiles are generally longer than 3.5 inches, medium from 2.7-3.5 inches and short are under 2.7 inches.
Montana varieties with short coleoptile length include Broadview, CDC Falcon, Colter, Keldin, Loma, Northern, SY Clearstone 2CL and Yellowstone. Montana Varieties with medium coleoptile length include Decade, SY Monument, Warhorse, and SB Quake. Montana varieties with long coleoptile length include Brawl CL plus, Rampart and Judee.
In conclusion, when sowing early, producers should carefully choose varieties and avoid those with varietal characteristics that can reduce germination.
Information for this article came from Oklahoma State University Extension (PSS-2256) and Montana State University Agricultural Experiment Station (2017 Winter Wheat Varieties page 3 and 22).
Montana State University, U.S. Department of Agriculture and Montana Counties Cooperating. MSU Extension is an equal opportunity/affirmative action provider of educational outreach.
