Nutrient Uptake by Intact and Disturbed Roots of Loblolly Pine Seedlings
نویسندگان
چکیده
1 Most measurements of nutrient uptake use either hydroponic systems or soil-grown 2 roots that have been disturbed by excavation. The first objective of this study was to 3 test how root excavation affects nitrate uptake. Rates of NO3 uptake by mycorrhizal 4 loblolly pine (Pinus taeda L.) seedlings were measured in intact sand-filled columns, 5 hydroponics, and disturbed sand-filled columns. Total nitrate uptake in intact sand6 filled columns was higher than in disturbed columns, indicating that disturbance 7 lowers uptake. Transferring plants from the sand-filled columns to hydroponics had 8 little effect on NO3 uptake beyond delaying uptake for an hour. The second 9 objective of this study was to determine whether NH4, Ca, Mg and K uptake 10 could be studied using sand-filled columns, since previous studies had tested this 11 method only for nitrate uptake. Uptake rates of NH4 and K were positive, while 12 Ca and Mg uptake rates were negative in intact sand-filled columns, indicating 13 that net efflux may occur even without physical disturbance to the root system. The 14 sand-filled column approach has some limitations, but holds promise for conducting 15 nutrient uptake studies with minimal disturbance to the root system. 16 17 18 19 20 21 22 23 24
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