Gibberellic Acid Usage Relieving Salinity Adverse Effects on Growth, Flowering and Bulb Production of Tuberose Plants (Polianthes tuberosa, L.)

Abstract

The current research was carried out during two successive seasons of 2017 and 2018 at the Nursery of Ornamental plants, Fac. of Agric., Minia University, to explore alleviating side effects of soil salinity on growth, flowering and bulb production of tuberose plants by usage of gibberellic acid (GA3). Different vegetative growth traits, flowering parameters and bulb production aspects were greatly and gradually reduced parallel to the increase in soil salinity level with the least values being given due to highest salinity level. In addition, flowering date was delayed due to salinity treatments. By contrast, all these traits were enhanced upward according to the increase in GA3 (50 or 100 ppm) concentration including earlier flowering. It could be concluded that, the counteraction between GA3 and salinity, for bulb production traits was significant in both seasons. The combined treatment of high salinized/high GA3 was capable of giving similar to those given by the un-salinized/un-gibberellin treatment. The role of GA3, when applied at 100 ppm to highly salinized soils (1.2%), in enhancing number, fresh weight and dry weight of daughter bulbs give rise to increases of 71.3, 40.8 and 37.8% in the first season and 66.7, 48.7 and 56.0%, in the second season, respectively. Therefore, tuberose plants could be produced, under salt affected soils, by the use of GA3 which counteracted hindered effects of salinity on plant growth and flowering. The application of such growth regulator resulted in growth, flowering and bulb productivity values nearly equalized those given by control treatments.