Development of Standard Concentrations of Foliar Nutrients for Saskatoon

Soil and foliar samples were collected from saskatoon orchards in Saskatchewan, Manitoba, and Alberta, Canada from 1997 to 1999 and analyzed for macro- and micronutrient content. Foliar samples were collected twice a month from the end of May until September in 1997 to examine the pattern of change in foliar nutrient concentrations throughout the season and to determine the most stable time period for foliar sampling. This period was determined to be from the last week in July until mid-August. Nutrient concentrations of foliar samples collected during this period from 1997 to 1999 were summarized according to the mean, median, minimum, and maximum values. Mean foliar nutrient concentrations were as follows: 2.48% nitrogen (N), 0.18% phosphorus (P), 1.15% potassium (K), 0.15% sulfur (S), 1.52% calcium (Ca), 0.50% magnesium (Mg), 6.9 ppm copper (Cu), 106 ppm iron (Fe), 124 ppm manganese (Mn), 16 ppm zinc (Zn), and 27 ppm boron (B). A number of significant positive correlations were found between soil and foliar levels of a nutrient, with the majority of these correlations occurring for the nutrients Cu, P, and Mn. Another study conducted during 2001–2002 examined differences in the foliar nutrient concentrations of the saskatoon cultivars ‘Smoky’ and ‘Thiessen’ sampled from nine orchards in Saskatchewan. Foliar concentrations of N, K, S, Ca, Mg, Cu, Mn, Zn, and B were significantly higher in ‘Smoky’ than in ‘Thiessen,’ whereas foliar K content was higher in ‘Thiessen’ than in ‘Smoky’.