Optimization of in vitro growth medium for a wild Kazakhstan apricot, Prunus armeniaca

Determining a growth medium for genetically diverse plants can be a very difficult task, even for closely related selections. This is a great barrier to preserving the genetic diversity of wild plants. Improved modeling methods for determining mineral nutrient requirements in vitro allow for more rapid and accurate experimentation for formulating new growth media. Response surface methodology (RSM) was applied for improving the growth of a Prunus armeniaca Lam. culture, from the mountains of Kazakhstan. Woody plant medium (WPM) mineral nutrients [calcium nitrate, ammonium nitrate, mesos (calcium chloride, potassium phosphate and magnesium sulfate), potassium sulfate and minor nutrients] were tested at five concentrations, each in a RSM experiment. Data taken included a subjective quality rating, shoot length, shoot number, leaf color, size and necrosis, shoot tip necrosis, and other physiological disorders. Shoot quality was the best when ammonium nitrate, calcium nitrate and mesos were increased. Calcium nitrate was the most significant factor for shoot multiplication, while shoot length was influenced by the interaction of ammonium nitrate and mesos. Leaf color and leaf size improved with higher nitrogen and mesos. Physiological disorders were more common with nitrogen or mesos deficiencies. Shoot tip necrosis occurred to a small extent in control WPM shoots and to a greater extent in treatments where all nutrients were low. Callus production decreased with increasing mesos concentrations. Fasciation was rare but did occur with high mesos and minors in combination with low potassium sulfate. A test medium with increased nitrogen (×1.75) and mesos (×2.5) produced greatly improved shoots of P. armeniaca. Additional experiments will be run to determine final concentrations of the mesos components and the nitrogen components as the next steps to optimization.