Quantifying the differential uptake of nutrients of different apple rootstocks under selected ambient summer temperatures in a pot trial in environmental chambers

The trial commenced this year with good quality cuttings with sufficient rooting. We changed the medium to include 30% compost in the sand mix to retain more water. Sufficient growth took place and we were able to do a mineral analysis as well as compare rootstocks in terms of growth. However, we still had unexpected death of plants after initial establishment and this was cultivar related. A 4^th year student partook in the trial.

The new growth of the different rootstocks were not influenced significantly by the three different air temperature regimes, but was a direct reaction of the specific rootstock. CG 9778 showed the most new growth but this was not significantly more than M7 and CG222. These showed more growth than CG8228 (not sign.) that showed more growth than CG 42022 (not sign.). M793 did not grow well under these conditions and we had some rootstock deaths that resulted in negative growth.  The genetic differences between the rootstocks was also the main reason for the differential uptake of the different nutrients supplied to the roots.