Effect of nitrogen and cane density on cane architecture, fruit and fruit yield components in primocane bearing red Raspberries

Nitrogen fertilization and cane density management are the most critical factors in the commercial production of red raspberries. In general, little is known about these factors in relation to primocane bearing red raspberries and their effect on fruit yield. In two separate experiments, four levels of nitrogen and four levels of cane density were investigated on 2 primocane bearing red raspberries, Rubus strigosus, selections '8008' and '8114', respectively. The experiments were conducted at three sites in Manitoba: a clay soil at st. Adolphe, a clay-loam soil at Morden, and a sandy soil at Souris. In the second year of the study (1991), only the latter two sites were used. A nitrogen response experiment was repeated in a soilless medium in a green house in 1991. Parameters investigated included number of flowers per lateral and per cane, fruit set, fruit yield (per cane and per plot), number of fruits per lateral, fruit size, fruit dry weight, cane height, cane diameter, number of nodes per cane, internode lengths, number of laterals per cane, length of xiii laterals and lateral branch angle. High nitrogen and low cane density had similar effects on fruit yield components: canes were larger in diameter, and the canes had more laterals which were progressively longer towards the bottom of the cane.