Effects of AGARRE on the Response of Maize to Potassium in Villaflores

The objective of the study was to determine the influence of a commercial seed treatment (AGARRE) that contains micronutrients and hormones on the response of maize to K supplied using two fertilizer sources at four application rates. The study was conducted at the experimental station of the University of Chiapas in Villaflores, Chiapas, Mexico. The field had a sandy loam soil (pH 4.8, 2.3% organic matter, 10 ppm Bray-1 P, 102 ppm available K, 508 ppm Ca, 98 ppm Mg, 17 ppm Na, 2 ppm Zn, 49 ppm Mn, 0.6 ppm Cu, and 0.4 ppm B). The effective cation exchange capacity of the experimental soil was 4 cmol/kg, with an exchangeable Al saturation of 8%. Treatments included AGARRE (0 and 250 mL/ha), K sources (KCl and K₂SO₄) and K rates (0, 60, 120, and 180 kg K₂O/ha). The resulting 16 treatments with two replications were arranged in an experimental design with split-split-plots, where the main plots had the application of AGARRE, the sub-plots had different K sources and the sub-sub-plots had K rates.

Due to the occurrence of extreme spatial variation in plant growth, grain was not harvested. The average plant height of tall, apparently normal plants was 216 cm, which was 27% greater than that of stunted plants (170 cm). Although apparently normal plants tended to be taller as the K rate increased, the effects were not statistically significant (p < 0.05). However, plant height decreased markedly when Mn concentration in leaves exceeded 90 mg/kg. The trial site had conditions conducive to Mn toxicity: low pH and reducing conditions due to water logging (caused by subsoil compaction) and abundance of organic residues from the previous crop.