Quantifying Spring Freeze Damage to Field Acclimated Winter Wheat and Potential Yield Impacts.

In the spring, soft red winter wheat (Triticum aestivum L.) can be affected by low temperatures causing farmers to be concerned about survivability and subsequent grain yield. Freeze tolerance guidelines were developed over 60 years ago in Kansas for hard red winter wheat. The goal of this research was to update freeze tolerance guidelines using modern soft red wheat cultivars under Ohio field conditions. The specific objective of this research was to evaluate cold tolerance of five wheat cultivars acclimated to two Ohio field locations. The cultivars were transplanted from the field into pots at Feekes growth stages: 6, 8 and 10.5 in the spring. Four replicates were placed in freeze chambers in a split-plot randomized complete block design. Main plot factor was temperature (°C): 4 (control), -3, -6, -10, and -15 and subplot factor was cultivar. Plants were exposed to the treatment temperature for 15 min, then removed and placed in a 4°C cooler. Dark-adapted chlorophyll fluorescence was measured within 16 h. Then, plants were moved to an open-air greenhouse. Plants were rated for percent survivability at 7 and 21 d after treatment using visual ratings and the Canopeo smart phone app. Plants were harvested at maturity to collect yield data on head number, seed number, seed dry weight, and plant dry weight. Yield was estimated comparing treatments to the non-freeze control of the same cultivar. Results will be presented.