Enhancing Grain Corn (Zea mays L.) Yield through Boron Application under High Temperature Stress during Reproductive Stage

Abstract

Climate change is projected to increase the frequency and intensity of extreme temperature events, including heatwaves, which can reduce grain corn productivity by impairing reproductive development. This study evaluated the effect of foliar boron (B) application on grain yield and kernel set of grain corn (Zea mays L.) cv. GWG5005 under high-temperature field conditions in Agroclimatic Zone 1 of Peninsular Malaysia, a region characterised by a clear and regular annual dry season. Field experiments were conducted at Sintok and Seberang Perai using a randomised complete block design with four foliar B application rates: 0.0 kg B ha⁻¹ (control), 0.5 kg B ha⁻¹, 1.0 kg B ha⁻¹ and 1.5 kg B ha⁻¹, applied at the flowering stage. During the growing season, maximum temperatures occasionally reached 35–39 °C, with seasonal average maximum temperatures of 35.8 °C in Sintok and 32.8 °C in Seberang Perai. Foliar application of 1.0 kg B ha⁻¹ significantly improved reproductive performance at both locations. In Sintok, the proportion of cobs with complete kernel set increased from 17.2% in the control to 59.5%, while in Seberang Perai it increased from 55.9% to 69.1%. Grain yield also increased significantly by 17.6% and 19.0% in Sintok and Seberang Perai, respectively, compared with the control. These findings indicate that foliar application of 1.0 kg B ha⁻¹ (equivalent to 3.29 kg boron trioxide (B₂O₃) ha⁻¹) at the tasselling stage improved kernel set and grain yield and may be considered as an adaptation strategy for grain corn under high-temperature stress. Foliar boron application therefore represents a potential agronomic strategy to enhance grain corn productivity under increasing temperature stress associated with climate change.