Plant Growth Retardants for Introduction of Native Reichardia Tingitana

Abstract

The adaptation of native plants to increase the diversity of marketable ornamental species and to preserve nature has been mainly focused on trees, shrubs and perennial plants, and less so on annual plants. Reichardia tingitana is a native plant of the southeast of the Iberian Peninsula, which produces attractive flowers from March to June. This plant produces stems, which are very tall and sinuous, with one terminal inflorescence. These two last features detract from the plant's use as a bedding plant. The ability of paclobutrazol (PBZ) and ethephon (ETH) to control the growth and development of the aerial part of this plant was investigated. PBZ (0.2, 0.3, 0.4 and 0.5 mg/pot) and ETH (25, 50, 75 and 100 mg/pot) doses were applied as a single soil drench 25 days after transplantation into 11 cm φ plastic pots. The most effective treatments were 0.5 mg/plant for PBZ and 100 mg/plant for ETH, which reduced plant height by 73.1 % and 50.3 %, respectively. PBZ (≥0.2 mg) and ETH (≥25 mg) significantly reduced plant width, aerial part dry weight, number of flowering stems and number of inflorescences per plant. None of the PBZ doses altered the inflorescence diameter, although all ETH doses reduced this parameter. PBZ (≥0.4 mg) and particularly ETH (≥50 mg) delayed the beginning of flowering. The results suggested that both PBZ and ETH could well be used to control the stem height of Reichardia tingitana and improve its ornamental value. However, we suggest future studies should look into the effect of time of application on plant height in an attempt to produce compact plants. Such studies will be able to determine the optimal relation between rates, moment of application and desirable plant height.

Assessing the Effect of Plant Growth Stimulants and Retardants on Cyclamen “Halios F1 Salmon Rose” Cultivar

“…Bosch et al 2016 [46] demonstrated that a high concentration of PBZ application can reduce the plant height to a desired level. Similar results were obtained in two different studies: containerized A. graminifolia [47] and R. tingitana [48]. Our results are in agreement with the published research.…”

“…In the case of PBZ treatment, we measured the lowest values. Another research study conducted with Reichardia tingitana showed that none of the PBZ doses altered the inflorescence diameter [48]. In contrast, we measured the lowest inflorescence diameter in control and PBZ-treated cyclamens.…”

Effect of paclobutrazol in potted plants of four cultivars of Dianthus barbatus × chinensis

“…No PBZ dosages applied to D. barbatus × chinensis altered the corymb diameter with respect to control. In other species, both cases of no PBZ effect on flower/inflorescence size (Yewale et al, 1998;Bañón et al, 2003;Mansuroglu et al, 2009) or, on the contrary, a reducing effect (Ranney et al, 1994;Al-Khassawneh et al, 2006) have been reported. Time to flower in D. barbatus × chinensis was markedly longer in autumn-to-spring cycle than in summer-to-autumn cycle probably for climatic reasons, and some differences in flowering time were observed among the cultivars, but PBZ treatment did not affect this parameter in any season and any cultivar.…”

“…There is much evidence that PBZ has an enhancing effect on leaf colour. Darker foliage was observed in PBZ-treated plants of different ornamental plants, like Cymbidium (Pan and Luo, 1994), Dicentra spectabilis (Kim et al, 1999), oleander (Bañón et al, 2001), Dianthus caryophyllus (Bañón et al, 2002), Reichardia tingitana (Bañón et al, 2003), Consolida orientalis (Mansuroglu et al, 2009), andazalea (Meijon et al, 2009). The darkening of the leaves due to PBZ has been related to their increased chlorophyll level (Pan and Luo, 1994;Nasr, 1995).…”

“…Paclobutrazol has demonstrated to provide height control in a large number of floriculture crops, including several flowering potted plants (Faust et al, 2001;Bañón et al, 2002;Meijon et al, 2009;Currey and Lopez, 2010;Newton and Runkle, 2010;Larcher et al, 2011;Wahyuni et al, 2011). In addition, PBZ has been reported to increase plant ornamental value by enhancing flowering (Mishra et al, 2005;Thompson et al, 2005) and foliage colour (Bañón et al, 2001(Bañón et al, , 2002(Bañón et al, , 2003Mansuroglu et al, 2009;Meijon et al, 2009).…”