2017 ASHS Annual Conference

In a grafting trial planted in 1999 at Kearney (Agricultural Research and Extension Center) in Parlier (CA), we evaluated the foliar nutrient concentration over the growing season in 2016. Shoots of two varieties of Southern Highbush blueberry: “Star” and “Jewel” were grafted on to rootstock of sparkleberry (Vaccinium arboreum). We compared nutrients between shoots of the two varieties when grafted or when ungrafted, in comparison to shoots of V. arboreum. The first thing that we observed was that the rootstock had a different phenology when compared with the two varieties of blueberry. However, when the nutrient concentrations were tracked with time, it was observed that the foliar concentration of Fe, Mg, Ca, B and Al tended to increase from the green fruit stage to the after the harvest stage in blueberry for all the species. On the other hand, N, P, Cu and Zn decreased in the same period in all species, and the rest of the nutrients remain in similar concentration over the growing period 105 days. Thus, some immobile nutrients accumulated in mature leaves with time, while highly mobile nutrients were presumably allocated to growing tissue. When we compared all treatments within a day, it was observed that sparkleberry showed higher concentration of all minerals with the exception of Ca and Cu, which were higher in Star when grafted. It is important to highlight that the difference in foliar concentration between sparkleberry and blueberry was highly significant for Mn and Zn, where in all the days evaluated, the concentration of these two micronutrients was double in the shoots of the rootstock. Finally, with the exception of S, it seems that the grafting does not have advantage in enhancing foliar concentration when compared to non-grafted plants.