Effects of Periods of Localized Water Stress on Subsequent Nutrient Uptake by Barley Roots and Their Adaptation by Osmotic Adjustment

Abstract

SUMMARYDrought and low soil water potentials depress nutrient uptake by roots, but their capacity for recovery when the soil is re-wetted has received less study. We investigated the uptake in barley of labelled phosphate and calcium from sand culture following periods of drought or treatment with polyethylene glycol 4000 (PEG) of the surface layers of the sand, with the lower portion of the root system receving ample nutrients and water. Drought diminished uptake and translocation of both nutrients and caused death of fine lateral roots, but after 3 days of re-wetting, uptake per unit fresh weight of roots was comparable with that of well-watered control plants despite apparent collapse of some of the cortical cells of the seminal axes. The activity of new nodal roots that grew during the 3-day re-wetting period alleviated the earlier depression of nutrient absorption. Effects of PEG (-0-8 MPa) were less severe and nodal roots grew through this medium with no apparent damage. The tips of these roots seemed to become osmotically adjusted largely by enhancement of their sugar content, but we found little evidence of such adjustment in those parts of the seminal axes exposed to PEG. Rapid growth of nodal roots assisted by osmotic adjustment may be of adaptive significance in ensuring resumption of nutrient and water uptake following periods of water deficit.

The relationship between the entry of isoproturon into Alopecurus myosuroides and its effect on growth and CO2 fixation

“…This estimated value is similar to that calculated from the nutrient culture experiments despite the assumption that all roots were exposed to a uniform average herbicide concentration in the soil. Shone & Flood (1983) also found no compensatory increase in root weight in non-stressed compared to drought-stressed parts of root systems which contrasts with other reports of compensatory uptake of water (e.g. Where only the primary or secondary roots were treated with 1 pg/l5 ml/l 1 days (Table 2) there was no evidence of increased nutrient solution uptake by the untreated roots.…”

The Efficiency of Nutrient Acquisition over the Life of a Root

“…For example, Larrea tridentata exhibited a fivefold increase in d 15 N as soon as 3 days after watering, compared to unwatered controls (BassiriRad et al 1999). Nutrient uptake recovery in Larrea was attributed primarily to increased root growth, similar to that found in wheat (Brady et al 1995) and barley (Shone and Flood 1983).…”

Root Growth, Osmotic Adjustment and NO3- Uptake During and After a Period of Drought in Artemisia tridentata

“…Although we suggest that post-drought recovery of NOS uptake was uncoupled from root growth in A. tridentata seedlings, the potential contribution of root growth to recovery of water and other nutrient uptake should not be underestimated (Shone and Flood 1983;Lauenroth et al 1987;North and Nobel 1991;Thomas 1991). Recovery of q,, reported within 4 days after rewetting (Fig.…”

“…after a rainfall event, results in increased water uptake and resumption of plant water status (Nobel and Sanderson 1984;Lauenroth et al 1987). Rapid root proliferation following rewetting may also be a plastic response adapted to resume nutrient uptake, particularly for slow diffusing ions such as P (Shone and Flood 1983). However, more recently Jupp and Newman (1987) reported that post-drought P uptake in pre-stressed rye grass was unrelated to initiation of root growth.…”