Effects of Foliar Application of Plant Growth Regulators on germination Enzyme Activities in the Wild Barely (<i>Hordeum spontanium</i>)

Abstract

Wild barley, from the Gramineae family, due to primary dormancy, is one of the most important weed in wheat. We hypothesized that foliar application of plant growth regulators (PGRs) affects breaking dormancy in wild barley via germination enzyme activities and seed germination immediately on the mother plant to reduce soil seed bank. To measure the activity of enzymes alpha-amylase, protease, and invertase, two experiments were conducted based on a completely randomized design with 3 replications at the University of Kurdistan farm and Laboratory in 2016 and 2017. In the first experiment the highest and lowest alpha-amylase activity was obtained in gibberellin treatment at a concentration of 100 mgL<sup>-1</sup> and control treatment on hull seed, respectively. The activity of protease enzyme in applied treatments had a similar trend as 100 mgL<sup>-1</sup> of gibberellin treatment. The highest and the lowest protease activities were 12.62 and 3.82 Ug<sup>-1</sup> related to gibberellin treatment at a concentration of 100 mgL<sup>-1</sup> and control treatment, respectively. The second experiment was conducted to investigate the effect of time of PGRs foliar application on the parent plant on the activity of enzymes. Gibberellin 100 mg<sup>-1</sup>, salicylic acid 0.5, and 1 mM treatment on the mother plant produced the highest alpha-amylase, invertase, and protease activities when used after 50 days after pollination, there was no uniform trend in enzymes activity. In general, gibberellin treatment at a concentration of 100 mgL<sup>-1</sup> 50 days after pollination produced the highest activities of germination enzyme activities.