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The response of rose flower yield to hypoxia has been discussed in the literature, but there is still a lack of sufficient data on plant performance as affected by dissolved oxygen concentration in solution (DOC) and uptake flux by roots, to support efficient aeration control. The objective was to study Rosa L. response to DOC by characterizing oxygen consumption rates, leaf contents of nutrients and sugars, and cut-flower yield. Five levels of DOC in solution, ranging from 7.5 to 1.7 mg/L, were investigated. In winter and early spring DOC ≥2.5 mg/L was sufficient to satisfy plant demands for oxygen. In late spring and summer the required DOC was ~5 mg/L, corresponding to an O2 influx of 0.55 mg gfw−1 h−1. When DOC in summer was 1.7 mg/L the accumulation rate of Mn, Zn, P, Mg, and K in leaves was inhibited relative to DOC ~5 mg/L, transpiration declined, starch and polymerized glucose accumulated in leaves, and cut-flower yield decreased. Indications in solution were reduced capacity to decrease pH after the May harvest, which stemmed from reduced H+ efflux from roots, and stronger decline in EC due to decreased transpiration. |
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