Contrasting first-crop corn hybrids with different growth cycles in response to defoliation levels and sowing datesDamage caused by diseases, pests, or adverse weather conditions in the reproductive stages of corn crops results in reduced grain yield. However, studying the contribution of leaves in new hybrids is an alternative that makes it possible to reduce this damage. Therefore, this study aimed to contrast the effect of artificial defoliation at the R1 stage on the agronomic traits of four corn hybrids in a high-altitude region in two sowing seasons. The experimental design was randomized blocks in a 4 × 4 × 2 factorial scheme, referring to four defoliation levels (1- no removal of the leaf blade; 2- removal of all leaves; 3- removal of all leaves above the ear, and 4- removal of all leaves below the ear) × four hybrids (P1225 VYH, P3016 VYHR, DKB 345 PRO3, and P4285 VYHR) x two sowing dates (October and November), with four replicates. The loss of leaf area above the ear decreases the number of grains per ear by 19.5%, 1000-grain weight by 11%, and grain yield by 44.5% for the hybrids and sowing seasons studied in a high-altitude region. Grain yield was increased by sowing in October by 23% compared to November. The hybrid DKB 345 PRO3 obtained the highest grain yield at all defoliation levels at the R1 stage under the conditions of Guarapuava, PR.
Key words:
Zea mays; climatic zoning; yield performance; radiation interception
Removing the upper third leaf reduces the grain yield of corn hybrids of different cycles at high altitudes.
The edaphoclimatic conditions of October positively influence the agronomic traits compared to November.
The hybrid DKB 345 PRO3 had the highest grain yield in the different levels of defoliation studied at the R1 stage.
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