The application of rapid chemical tests to the diagnosis of mineral deficiencies in horticultural crops. I. Crops grown on a manurial trial

Nicholas, D.J.D.

Jour Hort Sci 24(2): 72-105


DOI: 10.1080/00221589.1948.11513681
Accession: 013860852

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A short review of previous analytical work is given. The material used was from a long-term manurial trial and special attention was given to potato, tomato and cauliflower, though some samples of apple and black current were run. Leaves from midstem portions of potato and tomato were used the first upright leaf outside incurled leaves on the cauliflower, and 3d and 4th basal leaves taken from well-exposed leader shoots on apple and black currant. For tissue tests small petiole portions from numerous leaves at approx. half way between leaf attachment and base of lamina were used. For ash analysis the leaves, including the petiole, were dried 48 hrs. in aerated oven and then milled. A wet digestion procedure is described and soluble nutrients extracted with Morgan's reagent as described in previous papers. Directions are given for clearing tissue extracts that may be colored by flavones, tannins and other phenolic compounds. Chemical tests and coloration or turbidity ranges for K, Ca, Mg, Mn, NO3, PO4, and Cl are presented in a table. This rapid chemical tissue test was used to diagnose deficiencies of K, Mg, P, N, and Mn in potatoes and cauliflower. The test reflects the effects of manurial treatments and shows differences in the nutritive status of different crops grown on the same plot. The results obtained showed good agreement with visual diagnosis and it was possible to fix threshold values at which deficiencies of K, Mg, P and N produced visual symptoms. Nitrate was found to fall continually as the season progressed, and the nitrate test could not be used to determine N status in potatoes and cauliflower late in the season. Data from one center of planting showed that K and N deficiencies caused significant reduction of crop wt. in potatoes and that in cauliflower N deficiency was largely responsible for low yields. A close correlation was found between data from tissue tests and full chemical analysis over the range of values useful for the diagnosis of deficiencies; at higher nutrient levels found in healthy plants the tissue test method did not always distinguish the differences shown by full analysis. The speed and ease of the tissue test method may make it suitable for advisory and survey work.