Abstract

This study aimed to investigate the effect of nitrogen fertilizer rates and split applications on the growth of maize hybrid Suwan 5821. The experiment followed a Randomized Complete Block Design with four replications, and a 2 x 3 factorial design was utilized, with two nitrogen rates at twice and four times the recommended amount based on soil test),, and three split nitrogen application rates (2:6:2, 4:4:2, and 5:5:0) were assigned. The study collected data on plant height (PH), leaf area (LA), leaf area index (LAI), SPAD of leaf above ear (SPADLeE), and chlorophyll of the leaf above ear at blister stage (R2). The study found that applying nitrogen fertilizer at a rate four times higher than twice the standard rate resulted in significantly higher values for PH, LA, LAI, SPADLeE, chlorophyll a, b, and total chlorophyll of leaf above ear compared to applying nitrogen fertilizer at twice the standard. The increases were 8%, 18%, 18%, 6%, 17%, 16%, and 20%, respectively. Additionally, the Pearson's correlation analysis revealed a positive correlation between SPADLeE and chlorophyll a, b, and total chlorophyll.