Optimizing rose crop fertilization and irrigation over hourly, daily and seasonal time scales: Ion and water uptake over daily cycles
In our last report we showed preliminary data on the uptake of water and nutrient by â€˜Happy Hourâ€™ roses over the course of an individual flowering cycle, and found that the two rootstocks we used had no significant influence over those uptake patterns (being similar in both rootstocks). These cyclical uptake patterns were similar to those previously reported by us and other researchers (Cabrera et al., 1995; Mattson and Lieth, 2005). The results indicate that still source-sink relations, specifically the sink strength â€“ or the phothosynthate demand of an organ at specific points in time â€“ define to a greater extent the pattern of nutrient uptake and reserve mobilization. In this case, the developing flower shoots, at the time when they are rapidly developing (elongating and growing) dominate the allocation of photosynthates (carbohydrates) that little is available for roots growth and function (i.e. nutrient uptake), even in the case of an extremely vigorous root system like â€˜Natal Briarâ€™. Growers will certainly acknowledge and appreciate the size and vigor of â€˜Natal Briarâ€™ over that of the old â€˜Manettiâ€™. While it is acknowledged that â€˜Natal Briarâ€™s vigor is transferred to the scions (cultivars) growing on it - one of the reasons for its adoption as rootstock - the carbohydrate demand (sink strength) of the developing shoots of the scion still dominates its allocation, causing the same cyclic nutrient uptake pattern regardless of rootstock vigor.
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Keywords: ICFG Hill Final Report 2007-2008