Effect of Foliar Application with IAA on Some Growth Parameters in Three Corn (Zea mays L.) Genotypes

Abstract

The research was conducted during the growing season 2019 in the Faculty of Agriculture, Damascus University, to study the effect of foliar application with Indole 3- acetic acid (IAA) on some growth parameters in three corn genotypes. The IAA solution was applied on the leaves after 20 days from sowing date using three different concentrations (0, 1, 25 and 300 ppm IAA). The experiment was designed using RCBD with three replications. The average plant dry weight was significantly higher in the line) IN-272-06( (2.65), the hybrid (IN-239-14 × IN-456-06) (2.53) at 300 ppm  IAA while it was significantly lower in the two genotypes (IN-272-06) and (IN-90-14 × IN-272-06) at the control treatment without significant differences between them (1.43 and 1.45 g respectively). The absolute growth rate and the leaf area index were significantly higher at the IAA level of 300 ppm in the genotypes (IN-272-06) and (IN-239-14 × IN-456-06) with no significant differences between them (12.93 and 12.47 g day^-1; 5.26 and 4.35 respectively), while it was significantly lower in the hybrid  (IN-90-14 × IN-272-06) at 1 ppm IAA and the control without significant differences between them (4.27 g day^-1 and 4.36  g day^-1; 2.18 and 3.21 respectively). The average of leaf area duration was significantly higher at the IAA  concentration 300 ppm in the three studied genotypes (IN-272-06, IN-90-14 × IN-272-06 and (IN-239-14 × IN-456-06) with no significant differences among them (46.96, 44.59 and 44.35 cm² day^-1 respectively), while it was significantly lower in the genotypes (IN-90-14 × IN-272-06)  at 1 ppm IAA and (IN-272-06) in the control treatment with no significant differences (20.20 cm² day^-1  and 22.79 cm² day^-1 respectively). Generally, the corn line IN-272-06 and the hybrid (IN-90-14 × IN-272-06) were more responsive to IAA treatment and the growth parameters increased proportionately with the level of applied auxin.