Effect of changes in substrate salinity on the elongation of Rosa hybrida L. ‘Kardinal’ stems

• DOI: 10.1016/j.scienta.2003.09.013
• Publication Date: 2003-12-13T11:45:16Z
• Authors: Lorence R Oki; J.Heinrich Lieth
• Keywords: Elongation

Abstract Changes in stem elongation rates of Rosa hybrida L. ‘Kardinal’ stems were measured using linear displacement position sensors (LDPS) while plants were exposed to salinized nutrient solutions for 2 or 12 h. Greenhouse-grown plants were acclimated for at least 24 h in a growth chamber before treatment. While in the growth chamber under constant 25 °C and continuous light, plants were automatically irrigated based on substrate moisture tension with half-strength modified Hoagland’s nutrient solution in demineralized water (NS). In the 2 h exposure experiment, a pretreatment irrigation of NS was initiated at 1:00 a.m. and was followed 2 h later by an application of demineralized (deionized) water (DI), NS, or NS with NaCl to increase the solution electrical conductivity (EC) by 1, 2, 4, or 8 dS m −1 (+1, +2, +4, and +8, respectively). A post-treatment irrigation with NS followed after two more hours. The shoot elongation rate (SER) of plants treated with DI increased by 0.30 mm h −1 from 0.95 mm h −1 , then returned to the pretreatment rate after the final irrigation. Treatment with NS resulted in a growth rate 0.10 mm h −1 greater than the pretreatment rate. This was unexpected and is probably due to a temperature effect caused by irrigating with cold solution. The +1 treatment had no effect on growth rate, but the higher concentrations resulted in decreases in SER of 0.12, 0.23, and 0.86 mm h −1 , respectively. Shoot growth rates of salinized plants returned to or exceeded pretreatment rates after the final leaching irrigation. In a 12 h exposure experiment, the treatment solution was not leached and data was collected for 12 h after the treatment. Treatment with +2, +4, and +8 caused immediate, but temporary reductions in SER. Growth rates then increased and restabilized after 4–6 h. Stems of the +2 and +4 treated plants regained the pretreatment elongation rates, but +8 treated stems only partially recovered at 78% of the pretreatment rate.