Effects of the Combined Application of Ethephon and Gibberellin on Growth of Rice (Oryza sativaL.) Seedlings

Effects of combinational treatment with ethephon and gibberellic acid on rice seedling growth and carbohydrate mobilization in seeds under flooded conditions

“…Subsequently, the seeds were treated with ET (2-chloroethylphosphonic acid; Ishihara Sangyo Kaisha Ltd., Osaka, Japan), an ethylene-releasing compound (Arteca, 1996), and/or GA 3 (Sigma Chemical Co., MO, USA) as follows: the seeds were treated with one of the following solutions for 48 h: (1) water (control), (2) 250 mg L -1 ET, (3) 20 mg L -1 GA 3 , or (4) 250 mg L -1 ET + 20 mg L -1 GA 3 (ET+ GA 3 ). The concentration of ET and GA 3 was determined by referring to those of Watanabe et al (2007), and by preliminary experiments. After treatment, the seeds were briefly washed with water to remove any excess solution.…”

“…Early seedling growth, including seedling emergence and vigor, is crucial in direct seeded rice systems. Seedling growth can be improved by treating the seeds with plant growth regulators (PGRs), such as gibberellin (GA), ethylene, and abscisic acid (ABA), which are known to affect the elongation of rice seedling organs (Furukawa et al, 1997;Raskin & Kende, 1983;Suge, 1974;Takahashi & Kaufman, 1983;Watanabe and Takahashi 1997;Watanabe et al, 2015Watanabe et al, , 2007. Suge (1974) reported that ethylene combined with GA 1 , a naturally active GA in rice, stimulates the growth of the coleoptile and first leaf in rice.…”

“…Furukawa et al (1997) suggested that the synergistic effect of ethylene and GAs on leaf elongation could be attributed to an increased responsiveness and turnover of GA 1 by ethylene. Our previous study showed that simultaneous application of ethephon (ET) and gibberellic acid (GA 3 ) improved the early growth of rice at different growth temperatures and flooding depths under field and environmentally controlled conditions (Watanabe et al, 2015(Watanabe et al, , 2007, however, the physiological mechanism underlying the synergistic effect of ET and GA 3 on seedling growth remains unsolved, despite the above-mentioned report by Furukawa et al (1997).…”

“…Vigorous seedling growth is crucial when rice seeds are sown in flooded paddy fields. For instance, the elongation of seedling organs, including mesocotyl, coleoptile, and first leaf, plays an important role in the emergence and establishment of direct seeded rice (Hoshikawa, 1993;Mori et al, 2012;Ogiwara & Terashima, 2001;Watanabe et al, 2015Watanabe et al, , 2007Watanabe et al, , 2006. Further, various physiological processes, including starch and sugar metabolism, are involved in the seedling growth of rice under flooded conditions (Ismail et al, 2009;Magneschi & Perata, 2009).…”

Effect of Gibberellin and Uniconazole on Mesocotyl Elongation of Dark-Grown Maize under Different Seeding Depths

“…It is reported that endogenous GA plays a regulatory role in stem elongation of Cichorium intybus and Japanese radish, hypocotyl elongation of Arabidopsis and shoot elongation of tobacco, based on by the effect of uniconazole (UCZ), GA biosynthesis inhibitor (Demeulemeester et al, 1995;Nishijima et al, 1997;Tanaka et al, 2003;Ishida et al, 2004). On the other hand, exogenous GA can strongly stimulate internode elongation in dwarf GA 1 -defi cient mutants of pea, the fi rst internode elongation of wheat, and mesocotyl and coleoptile elongation of rice (Yang et al, 1996;Chen et al, 2001;Cao et al, 2005;Watanabe et al, 2007). Exogenous GA can promote hypocotyl elongation in light-grown Arabidopsis (Xu et al, 1997), but not in darkness (Cowling and Harberd, 1999).…”