Abstract

This study aimed to investigate the effects of nitrogen fertilizer rates and split applications on the growth of maize hybrid Nakhon Sawan 5. The experiment followed a Randomized Complete Block Design with four replications, and a 2 x 3 factorial design was utilized, with two nitrogen rates (a rate of two and four times the recommended amount based on soil test) and The split application of nitrogen fertilizer was done in three different rates, with ratios of basal application: first top-dressing application: second top-dressing application set at 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 results indicated that applying nitrogen fertilizer at a rate four times resulted in significantly higher values of LA, LAI, SPADLeE, Chlorophyll a, b, and total chlorophyll of leaf above ear, as compared to a rate two times. The increases were 44%, 44%, 10%, 21%, 25%, and 16%, respectively. In terms of the interaction effect between rates and split applications of nitrogen fertilizer, a rate four times at 2:6:2 showed a higher plant height compared to a rate two times at 2:6:2, 4:4:2, and 5:5:0, with an increase of 40%, 26%, and 30%, respectively. Additionally, there was a positive correlation between SPADLeE and chlorophyll a, b, and total chlorophyll.