Impact of freezing temperatures on winter maize production in the Yaqui Valley, Sonora, Mexico

The objective of this work was to measure the physical damage and impact on production caused by freezing temperatures that occurred in January 2023 on the maize crop in the Yaqui Valley, Sonora, Mexico. Field trips were carried out to monitor the damage in 134 commercial fields which represented 5,256 hectares. The damage estimate was accounted for by visual inspection, calculating the percentage of green area affected by the freezing temperatures multiplied by the population damaged; also, the percentage of foliar damage and the sowing date were correlated with grain yield. Eighteen fields sown with different maize hybrids on different dates, and with different percentage of damage, were selected to evaluate the weather effect, by harvesting six random samples 1 m2. The number of ears per plant were counted considering the complete and incomplete ones, and the grain weight was standardized to 12 % humidity. The estimated average foliar damage in the total area monitored was 30.24 %. The lowest damage was related to the irrigation applied before the freezing temperatures occurred, while the greatest damage in fields sown early, was related to the phenological stages 9th to the 11th ligulated leaves. The interaction between foliar damage and grain yield indicated that for every 1 % damage, yield was reduced by 0.0228 t ha-1 and the average production of the fields by 1.85 t ha-1, while for late sowing, grain yield was reduced by 0.0638 t ha-1 per day of delay, and the average production of the fields by 1.53 t ha-1.