Factors affecting establishment of sweet cherry on gisela 6 rootstock

Abstract

Cristalina and Skeena sweet cherry cultivars (Prunus avium L.) on Gisela 6 (Prunus cerasus · Prunus canescens) rootstock were maintained for the first four growing seasons in a randomized, replicated split-split plot experimental design with two main plot irrigation frequency treatments, the two cultivars as subplots and three soil management subsubplot treatments. The same amount of irrigation water was applied through four drip emitters per tree at either high (I1, four times daily) or low frequency (I2, once every second day) beginning in the second year. Three different soil management treatments were established the year of planting and included: 1) NK fertigation with a herbicide strip (control), or additionally; 2) maintenance of a 10-cm thick bark mulch over the herbicide strip; and 3) annual fertigation of 20 g phosphorus (P) per tree per year immediately after bloom. I1 irrigation increased soil moisture (0- to 20-cm depth) throughout each growing season. The I1 irrigation resulted in higher leaf and fruit concentrations of the immobile nutrients P and potassium (K) and larger trunk cross-sectional area than I2 trees. I1 irrigation, in general, did not affect initial yield or fruit size. Fruit from I2 irrigation had higher soluble solids concentration (SSC), color, and total phenolic concentration at harvest in 2008 and lower titratable acidity (TA), firmness, and stem pull force suggesting an acceleration of fruit maturity. When compared with the control soil management treatment, P fertigation resulted in leaves and fruit with higher P concentrations, a higher 2008 crop yield, and a delay in 2008 crop maturity as indicated by lower harvest color and SSC and higher stem pull force. Mulch application, relative to control treatments, resulted in trees with higher vigor (but only with I1 irrigation) and leaf K concentration and had few effects on initial fruit yield or quality. There were important differences in cultivar responses to treatments. 'Cristalina' vigor was lower than 'Skeena' whose fruit had lower firmness and pedicel retention than 'Cristalina'.