SIGNIFICANCE OF THE pH OF BLUEBERRY LEAVES

Abstract

Ecologically, the swamp, or highbush blueberry, Vacxiniunt corymbosum L., differs fundamentally from other cultivated plants in its requirements for an acid soil, a conistant source of moisture (6), and a relatively high anion nutrient uptake (19). In conjunction with studies on blueberry nutrition presented elsewhere (19), data were obtained on the effect of mineral nutrient deficiencies and age of leaves on the pH of the blueberry leaf sap. It was thought that these studies on the pH of the leaf sap might offer the key to an understanding of the mechanism by which the swamp blueberry can live in its usual environment.Materials and methods Dormant rooted blueberry cuttings of the Cabot variety were planted on January 7, 1942, in 54 coffee urn liners (glazed crocks) containing quartz sand, and accommodating two cuttings per crock. Beginning ten days later, nine different nutrient solutions were applied, designed to induce the following mineral nutrient deficiencies: None, nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, and boron. The composition of the solutions and the method of application have been previously described (19). As an added precaution, each solution was adjusted to a pH of 4.8-5.0 with hydrochloric acid. In all, six liners (12 plants) were treated with each of the nine solutions. Four plants from each treatment were removed for analyses on February 22 (46 days after planting), four others on March 15 (67 days after planting), and the remaining four on April 10, 1942 (93 days after planting).Determinations of the pH of the plant sap were made by means of a Coleman pH electrometer (model 3). Immediately after the removal of each plant, the sap for pH determinations was prepared by grinding a representative part of the current leaf growth in a mortar with a few milliliters of distilled water and quartz sand and decanting the supernatant liquid into the cuvette of the pH apparatus.

Le bluet nain sauvage /

“…La récolte de 1935 fut de 5,000,000 livres. 11,437,485 livres en 1947, avec chute correspondante des prix moyens à Le Vaccinium pennsylvanicum et la V. canadense ne se distinguent pas dans les champs, en pratique. Les deux espèces croissent ensemble, bien que la première préfère les terrains acides, tourbières, gneiss laurentien, et la seconde les lieux humides et les bois rocheux.…”