Freising-Weihenstephan SunPatiens & New Guinea Impatiens cold tolerance trials April 2012 Garry Grueber / Cultivaris

Climate-controlled greenhouse compartments for NG/SP trials

SP/NGI trials at 12°C in temperature-controlled greenhouse compartment

Overview of 12°C compartment, 9 cvs, 4 repetitions with 10 plants/repetition SP Compact Orange SP Compact Magenta

SP Compact Magenta at 12°C – very vigorous and healthy

SP Compact Deep Rose SP Compact Orange SP Compact Magenta Overview 12°C compartment

NGI cv at 12°C, showing stunted growth and chlorosis

SP Compact Orange showing root development in hydroponic system at 12°C

NGI cv showing substantially weaker root growth in hydroponic system at 12°C

NGI cv showing leaf twisting at 12°C

NGI cv showing stunting and leaf deformation at 12°C

Lush growth of SP Compact Magenta at 12°C

Stunting and chlorosis with NGI cv at 12°C

Stunting, leaf deformation, anthocyanin influx and leaf drop with NGIs at 12°C

Severe stunting of NGI cv at 12°C, leaf drop and botrytis infection

SP Compact Orange grown in soil at 12°C, substantially smaller than plants grown in hydroponic system

SP Compact Orange at 12°C in hydroponic system: substantially larger and lusher due to optimized nutrition levels

Comparison between NGI cv (left) with SunPatiens Compact cv (right) at 12°C

Root system of NGI cv at 12°C

Root system of SP Compact Orange at 12°C

SP/NGI trials at 16°C in temperature-controlled greenhouse compartment

Overview 16°C compartment SP Compact Orange (significantly larger and lusher)

Overview 16°C compartment SP Compact Magenta

SP Compact Deep Rose SP Compact Magenta Trials in 16°C compartment

SP Compact Deep Rose at 16°C

Root system of SP Compact Orange at 16°C

Aggressive root system of SP Compact Orange, with individual roots growing right through styrofoam

Comparatively weaker root growth with NGI cv

Results of climate compartment trials Plants were always lusher and larger in hydroponic system due to optimized nutrient availability and uptake Flowers and buds were constantly removed and weighed, but it was confirmed that SunPatiens were substantially earlier to flower at all temperatures. SunPatiens have a more aggressive and larger root system At 12°C, SP Compact Orange and Compact Magenta had about 3 times the fresh mass of comparative NGI varieties Compact Deep Rose is substantially smaller than Compact Orange and Compact Magenta, especially at lower temperatures – comparable in size and performance to standard NGIs

SP/NGI climate-chamber trials with extreme cold stress (8°C and 4°C, control 20°C) to induce ethane production (instead of ethylene); goal was to see if ethane can be used as a quick test for cold tolerance. Cold exposure: 3-4 weeks

SP/NGI climate-chamber trials with extreme cold stress (8°C, after cultivation at 20°C) Cold exposure: 3-4 weeks

Same NGI/SP assortment as in hydroponic trials

Foliage drop and anthocyanin development at 8°C with NGI cv

SP Compact Magenta looking good at 8°C

Leaf twisting with NGI cv at 8°C

Leaf drop and botrytis with NGI cv at 8°C

SP Compact Orange looking good at 8°C

SP Compact Orange

What can we learn from these experiments?

SunPatiens thrive and perform at substantially lower temperatures than standard New Guinea Impatiens

At all three temperature regimes, SunPatiens were quicker to finish and quicker to flower than standard New Guinea Impatiens

Root mass and root development is significantly stronger and fuller with SunPatiens than with standard New Guinea Impatiens

Nutrient uptake is significantly higher with SunPatiens than with standard New Guinea Impatiens, hence need higher fertilizer rates for full performance

Without hardening off, SunPatiens will also suffer from sudden exposure to really low (above-freezing) temperatures.

Within the Compact series, there are still substantial differences in vigor, performance and cold tolerance between cultivars

Intense breeding and selection is needed to “true up” the Compact series and create a truly uniform, grower-friendly series

Most important: with SunPatiens, we have an exceptional product line that will perform extremely well under conditions that will damage and stunt competitive lines

Further research is needed to screen all SunPatiens varieties in the assortment, and all future varieties in the pipeline, in regard to cold tolerance

Further research is also needed to compare the cold tolerance of SunPatiens varieties with competitive lines such as SunHarmony

Many thanks and recognition goes to Dümmen for financing much of the research conducted, and for allowing us to share with the network