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EFFECTS OF PERIODS OF LOCALIZED WATER STRESS ON SUBSEQUENT NUTRIENT UPTAKE BY BARLEY ROOTS AND THEIR ADAPTATION BY OSMOTIC ADJUSTMENT
Author(s) -
SHONE M. G. T.,
FLOOD ANN V.
Publication year - 1983
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1983.tb04865.x
Subject(s) - nutrient , peg ratio , sugar , polyethylene glycol , wetting , phosphate , osmotic pressure , horticulture , chemistry , biology , root system , botany , agronomy , zoology , ecology , biochemistry , materials science , finance , economics , composite material
S ummary Drought 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.