Sign up for email alerts of new Fluid Journal issues!
Fluid Journal : Fluid Journal 2005-2007
effective as no B deficiency symptoms (such as corking and cracking of skin surfaces as observed in 1993) were observed on fruit harvested in the fall of 1994. Fertigation of 0.34 g B per tree increased soil solution B concentrations at 12-inch depth to values exceeding 1 ppm from background values less than 0.1 ppm soon after commencement of B fertigation in both 1995 and 1996 (Figure 3). Soil solution B concentrations returned to background values within two to three weeks after cessation of fertigation. The responsiveness of soil solutions B values to B fertigation is therefore similar to the responsiveness of soil solution NO3-N concentration to N fertigation. Like N, fertigated B is mobile within the soil and is anticipated to be similarly effective for plant uptake as fertigated N. Leaf B concentrations in 1995 and 1996 were well above deficiency and within the sufficient-optimum range for apples (31 to 60 ppm) for all cultivars. In general, leaf B concentration also increased for all cultivars between 1995 and 1996, suggesting a need to be cautious of plant B status when supplying B by fertigation in order to prevent over-application. The narrow margin between B toxicity and deficiency for fruit trees was recognized during early work on B deficiency. More recently research has suggested bud damage when leaf B concentrations exceed 60 ppm. There has been little fertigation research for micronutrients such as B on fruit trees, although the possibility has been recognized. Our results from 1995 and 1996 indicate that it is possible to supply B nutritional needs of apple via fertigation but vigilance is required to avoid B toxicity. Conclusions Evidence from this experimentation on high-density apple orchards indicates that deficiency of B, which has been observed for standard low- density orchards receiving broadcast fertilizer applications, is likely to develop rapidly when trees are fertigated with macronutrients N and K. Deficient leaf B concentrations occurred within two years on a range of fertigated apple cultivars planted in typical coarse-textured orchard soils and grown under environmental conditions typical of the semi-arid fruit- growing region of the Pacific Northwest of North America. Fertigated B was mobile within the soil and it was relatively easy to increase leaf and fruit B to adequate concentrations via fertigation of modest rates of 0.34 g B per tree. This information suggested strategies on B management would be applicable to most apple cultivars grown under similar production conditions. Dr. G. Neilsen is research scientist, Dr. D. Neilsen is research scientist, Dr. Hogue is research horticulturist, L. Herbert is research technician at Pacific Agri-Food Research Center, Agriculture and Agri-Food Canada, Summerland British Columbia, Canada.
Fluid Journal 2002-2004
Fluid Journal 2008-2009