Nutrient sufficiency levels for haskap (Lonicera caerulea L.) using the boundary-line approach

Adequate supply of plant nutrients is crucial for haskap plant growth and increased productivity. A study was carried out to determine the variability in haskap (Lonicera caerulea L. cv. Indigo Gem) plant characteristics in relation to soil and leaf tissue nutrient status. A total of 19 composite soil samples and corresponding plant leaf tissue samples were collected in 2016 from 12 locations in Nova Scotia. Plant parameters measured include growth rate, leaf size, leaf chlorophyll content, and visual observations. A boundary-line approach was used to determine nutrient sufficiency ranges in leaf tissues of 2.23%-2.96% for N, 0.22%-0.28% for P, 0.84%-1.32% for K, 1.63%-2.10% for Ca, and 0.14%-0.50% for Mg. Principal component and correlation analysis suggested a possible antagonistic interaction between leaf K and Mg. Negative associations were observed most frequently between Ca and Mg and other nutrients, especially K. Plant parameters such as bush volume, leaf size, and growth rate were closely related to soil and leaf K. Deficiencies in leaf tissue K and P were identified as potentially important factors limiting growth. Therefore, there is a need to adjust or balance the application of these nutrients. In conclusion, the sufficiency ranges derived can be used as a guiding principle in diagnosing the nutritional status of haskap cv. Indigo Gem on representative farms in Nova Scotia.