https://journals.seagullpublications.com/ijtem/archive/f_IJ0320191017.pdf

Foliar-Applied Mineral Oil Enhanced Hormones and Phenols Content and Hastened Breaking Bud Dormancy In “Astrachan” Apple Trees

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Changes in Promoter and Inhibitor Substances During Dormancy Release in Apple Buds Under Foliar-Applied Dormancy-Breaking Agents

The oriental hybrid lily (Lilium oriental cv. Sorbonne) is an economically important flower noted for its pink petals. Flower quality is determined by plant height, number of flowers per plant, and flower diameter. The commercial value can be increased by improving flower quality through cultural practices such as exogenous application of hormones; however, information on this practice is unavailable for this lily hybrid. In the present study, we soaked lily bulbs for 24 hours in one of four concentrations of abscisic acid (ABA) or one of three concentrations of the ABA biosynthesis inhibitor fluridone before subjecting the bulbs to a cold storage treatment at 4 8C. During cold storage, bulbs were sampled and buds were collected every 10 days for 80 days (that is, lasting eight times). The ABA and gibberellic acid 3 (GA3) contents of buds of treatments that showed a significant difference with the control were measured in a 10-day interval. Greenhouse experiments with different cold storage durations of bulbs that measured height, flower number per plant, and flower diameter were conducted. The interaction of hormone treatments and cold storage duration played nonsignificant roles in parameters of flower quality. Exogenous fluridone application to bulbs at 12 mg·L improved flower quality: height and flower number increased significantly compared with the control, but flower diameter did not change. ABA had no effect on flower quality. Because the fluctuation of endogenous GA3 is more remarkable than ABA after the application of fluridone that led to the improvement of flower quality, it can be inferred that this influence on flower quality is achieved through fluridone’s regulation on the content of endogenous GA3. A low endogenous GA3/ABA ratio was associated with improved flower quality: 12 mg·L L1 fluridone decreased the GA3/ABA ratio in most times of the cold treatment. In addition, cold storage duration affected flower quality; the 50-day cold storage can achieve the highest height, the most flower number, and bigger flower diameter simultaneously. The results of the present study suggest that soaking bulbs in 12 mg·L fluridone before cold treatment followed by 50 days of cold storage before planting will increase plant height and flower number per plant. The oriental hybrid lily (Lilium spp.) is one of the most popular ornamental plants worldwide. The Sorbonne cultivar is an economically important flower noted for its fragrance and pink petals. It has auspicious implications in Chinese culture and is favored by Chinese customers; as a result, it is one of the three most popular lily cultivars in China (Yamagishi and Akagi, 2013). The flower quality is mainly related to plant height, flower number per plant, and flower diameter (Lindsay et al., 1998; Savvas et al., 2002; Sohn et al., 2003). Improved flower quality is important in commercial production to improve market competitiveness and grower revenues. Regulation of plant growth and development by hormone application is an effective way to improve flower quality, but little knowledge is available on how to achieve this for the hybrid lily. Previous research suggests that ABA application inhibits plant height growth or stem elongation in Imperial Japanese Morning Glory at 25 and 50 mg·L (Pharbitis nil; Nakayama and Hashimoto, 1973), apple with 5 mL ABA at 50 mM (Malus hupehensis and M. sieversii; Ma et al., 2008), and pepper at 250 mg·L by drench with different frequency and timing (Capsicum annuum ‘Aristotle’; Biai et al., 2011). Exogenous ABA reduced (0.1 mg·L) or completely inhibited (1.0 mg·L) in vitro formation of leaves generated from the scales of oriental hybrid lily (Lillium cv. Siberia; Zhao et al., 2010). However, in some species, ABA plays a positive role; it increases shoot length in yerba mate (Ilex paraguariensis; Sansbero et al., 2004) and flower formation in Blue Torenia (Torenia fournieri; Tanimoto and Harada, 1981) and sacred Tulsi (Ocimum sanctum; Nair et al., 2009). In addition, ABA increases floral bud initiation, the number of inflorescences, and the number of flowers per inflorescence. High endogenous ABA levels increase the percentage of leafless inflorescences and the number of flower buds per node in Satsuma mandarin (Citrus unshiu ‘Okitsu’; Koshita et al., 1999) and apple (M. domestica cv. Redchief; Cao et al., 2000). On the other hand, flower bud formation in explants of tobacco (Nicotiana tabacum ‘Samsun’) was inhibited by ABA application at 10, 100, and 1000 mM (Barendse et al., 1985). Fluridone {1-methyl-3-phenyl-5-[3 (trifluoromethyl)-phenyl]4-[1H]pyridone} inhibits the production of phytoene desaturase, and therefore blocks the carotenoid biosynthesis pathway and indirectly inhibits the biosynthesis of ABA in plants (Arias et al., 2005; Chae et al., 2004; Harvey et al., 1994; Hoffmann-Benning and Kende, 1992; Kusumoto et al., 2006). Therefore, fluridone influences many physiological processes through its effect on the ABA level. For example, fluridone application at 25 or 125 mM for 24 h decreased the number of buds of a hybrid between Japanese bunching onion and shallot (Allium wakegi cv. Kiharabansei No.1; Yamazaki et al., 1999), decreased mesocotyl length of rice (Oryza sativa cv. JC 91) at 10 mM (Watanabe et al., 2001), and HORTSCIENCE VOL. 50(4) APRIL 2015 559 GROWTH REGULATORS

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Response of Oriental Hybrid Lily (Lilium oriental cv. Sorbonne) Flowers to Exogenous Fluridone and Abscisic Acid Application and Responses of Endogenous Abscisic Acid and Gibberellic Acid 3

Dormancy in lily (Lilium sp.) bulbs is broken by a cold period of several weeks. Sprouting percentage, growth and flower quality are reduced when bulbs are partially released from dormancy. To understand the involvement of phytohormones in dormancy release in lily bulbs, the concentration of endogenous abscisic acid (ABA), gibberellic acid (GA3), zeatin (ZT) and 3-indoleacetic acid (IAA) was examined in the primary shoot, outer scale and root of bulbs of Oriental hybrid Lilium ‘Siberia’ during the dormancy release period. Cold treatment (4 °C) enhanced ABA, GA3 and ZT concentration in the primary shoot. GA3, ZT and ABA reached their maximum levels on the 14th, 49th and 63rd days of cold storage, respectively. IAA concentration remained at a constant level in the primary shoot of bulbs at 4 °C up to 21 d. Thereafter, it increased gradually up to the maximum level on the 84th day. In the outer scale of the bulbs, GA3 increased dramatically on the 7th day, then declined till the end of the 4 °C treatment. In the root, GA3 was at a higher level in the bulbs at 4 °C than at 25 °C treatment before 42 d. The ratios of phytohormone that promote plant growth to phytohormone that inhibit plant growth were higher in the outer scale of the bulbs at 4 °C than those at 25 °C treatment before 42 d. The ratios were lower in the primary shoot of the bulbs after 42 d of the 4 °C treatment than those at 25 °C. In conclusion, cold treatment enhanced ABA, GA3 and ZT concentration and effectively regulated IAA concentration to reach the maximum level at the end of dormancy release period in the primary shoot of bulbs under 4 °C treatment. Apparently, changes in ABA and GA3 concentration differ in the primary shoot, outer scale and root of the bulbs of lily. These changes act as multipurpose signals in the control of bulb dormancy release in the different tissues of the bulb and during the different stages of bulb development. Apparently, there is a relationship between ABA and IAA concentration and bulb sprouting. Key Words: bulb, dormancy, Lilium sp., phytohormone

Variation in Endogenous Concentration of Abscisic Acid, Gibberellic Acid, Zeatin and 3-Indoleacetic Acid during Cold Storage in Bulbs of Lily (Lilium ‘Siberia’)

Lizhe An

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Variation in Endogenous Concentration of Abscisic Acid, Gibberellic Acid, Zeatin and 3-Indoleacetic Acid during Cold Storage in Bulbs of Lily (Lilium ‘Siberia’)