Project Number: 3607-21000-011-05
Project Type: Specific Cooperative Agreement

Start Date: Aug 31, 2004
End Date: Jul 14, 2008

Objective:
The objective of this cooperative project is 1) identifying the signal that initiates sudden pH decline (SPD) syndrome in geranium and learn to control that signal, 2) identify parent germplasm in order to establish the genetic relationships between susceptible cultivars, and 3) develop linkages between SPD in geranium with SPD in marigold and the reciprocally related problem of excess pH increase in other bedding plant species.

Approach:
A list of geranium cultivars known to be susceptible and resistant to SPD will be compiled through personal communications with geranium breeders, propagators, and the Ornamental Plant Germplasm Center. Cultivars will be collected that represent the categories Seed-hybrid, Zonal-cutting, Zonal-ivy, and Zonal-Regal and tested for their susceptibility to SPD syndrome. With these lists, we will work with breeders to establish the genetic relationships of the susceptible cultivars. The signal that turns on SPD in geranium will be found by testing specific environmental stresses such as iron or phosphate deficiencies, shifts in ammonium:nitrate ratios or cation:anion balance. We will determine how to manipulate the signal to avoid turning on SPD. Literature searches will be used to identify other susceptible species. Information gathered in determining the causes of SPD will be used to evaluate similar signals for the analogous problem of excess pH increase in other bedding plant species (calibrachoa, pansy, petunia, and vinca).