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- Author or Editor: P. L. Ager x
- HortScience x
Abstract
Roots of 53-day-old pecan seedlings [Carya illinoensis (Wangenh.) C. Koch] were either not flooded or flooded by submerging pots to ≈2 cm above the soil line in containers of water. Leaf gas exchange measurements at 1000 µmol·s–1·m–2 photosynthetic photon flux, 340 µl·liter–1 CO2, and 27°C were made prior to flooding, after 1, 8, or 15 days of flooding, and 7, 14, or 21 days after flooding was terminated. Net CO2 assimilation rate (A) decreased 56% after 1 day of flooding. Flooding 9 or 15 days did not further depress A. Carbon assimilation of trees that had been flooded for 8 days and then returned to nonflooded soil for 7 days were similar to unflooded trees. In contrast, A of seedlings flooded 15 days did not regain the A of unflooded trees 14 days after flooding terminated. Transpiration rates (E) paralleled A in all treatments. Leaf conductance to CO2 (g L ) was positively correlated with A (R2 = 0.94). However, leaf internal CO2 (Ci) concentration was not decreased by reduced gL. Water potential (ψ l ) and turgor potential (ψP) of leaves were higher when trees were flooded, but osmotic potential (ψs) was unaffected.
Abstract
Foliar K applications were evaluated on adult pecan trees [Carya illinoensis (Wangenh.) C. Koch.] in four separate experiments using various rates and timings of either K2SO4 or KNO3. Ammonium nitrate and/or urea also were used to enhance K absorption. Results indicated that foliar K applications using either K2SO4 or KNO3 were not effective in supplying K to the trees. Leaf K concentration, nut size, kernel percent, and yield, in most cases, did not respond to the treatments. Neither NH4NO3 nor urea improved K absorption.