scholarly journals Osmotic Adjustment in Cotton (Gossypium hirsutum L.) Leaves and Roots in Response to Water Stress

1987 ◽  
Vol 84 (4) ◽  
pp. 1154-1157 ◽  
Author(s):  
Derrick M. Oosterhuis ◽  
Stan D. Wullschleger
Keyword(s):  
Water Stress ◽  
Gossypium Hirsutum ◽  
Osmotic Adjustment ◽  
Gossypium Hirsutum L ◽  
Leaves And Roots ◽  
Response To Water

Osmotic Adjustment: Effect of Water Stress on Carbohydrates in Leaves, Stems and Roots of Apple

1995 ◽  
Vol 22 (5) ◽  
pp. 747 ◽  
Author(s):  
Z Wang ◽  
B Quebedeaux ◽  
GW Stutte
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Sucrose Concentration ◽  
Starch Content ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Malus Domestica Borkh ◽  
Mature Leaves ◽  
Young Leaves ◽  
Response To Water

Potted apple (Malus domestica Borkh. cv. Jonathan) trees were subjected to water stress in a greenhouse. Midday leaf water potential (ΨW), osmotic potential (ΨS), soluble carbohydrates, and starch content of expanding and mature leaves, stems, and roots were measured to determine whether active osmotic adjustment occurred and if water stress affected carbohydrate metabolism. Mature leaves had the highest total soluble carbohydrate level (357 mM) and lowest Ψ (-1.85 MPa), followed by young leaves (278 mM, -1.58 MPa), stems (115 mM, -1.02 MPa), and roots (114 mM, -0.87 MPa). Sorbitol was the major component in all organs ranging from 53% of total soluble carbohydrate in young leaves to 73% in mature leaves. When ΨW decreased from -1.0 to -3.2 MPa, active osmotic adjustments of 0.3-0.4 MPa were observed in mature leaves, stems, and roots while a significantly higher adjustment of 1.0 MPa was detected in young leaves 5 days after the initiation of water stress. Sorbitol levels in leaves and stems gradually increased as ΨW decreased from -1.0 to -2.5 MPa, and then remained relatively stable or decreased slightly as ΨW decreased from -2.5 to -3.2 MPa. However, the percentage of soluble carbohydrate as sorbitol in roots decreased in response to water stress. Sucrose concentration decreased in mature leaves and stems, but increased in young leaves and roots as ΨW decreased. Starch concentrations in stems and roots also decreased as water stress developed. The sorbitol to sucrose ratios increased in mature leaves, but decreased in roots in response to water stress.

Proline Analogues in Melaleuca Species: Response of Melaleuca lanceolata and M. uncinata to Water Stress and Salinity

1987 ◽  
Vol 14 (6) ◽  
pp. 669 ◽  
Author(s):  
BP Naidu ◽  
GP Jones ◽  
LG Paleg ◽  
A Poljakoff-Mayber
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Compatible Solutes ◽  
Species Response ◽  
Laboratory Conditions ◽  
Relative Water ◽  
Response To Water ◽  
First Time

Fifteen species of Melaleuca and two species of Callistemon from the field were examined to determine whether they accumulated nitrogen-containing compatible solutes and, if so, which. In addition to L-proline, N-methyl-L-proline (MP) (isolated for the first time from plants), trans-4-hydroxy-N-methyl- L-proline (MHP), and N, N'-dimethyl-trans-4-hydroxy-L-proline (DHP) were found in various combinations in the 15 Melaleuca species. M. lanceolata seedlings were subjected to water or salinity stress and M. uncinata to water stress under laboratory conditions. In both species significant reductions in leaf water potential (Ψw), osmotic potential (Ψs), turgor potential (Ψp), and relative water content (RWC) were observed in response to water stress. Salinised M. lanceolata plants showed considerable osmotic adjustment and maintained Ψp comparable to that of control plants; salinity, however, decreased RWC. In response to the imposed stresses under laboratory conditions, proline and MHP levels in M. lanceolata, and MHP and DHP levels in M. uncinata, increased. In addition to possible protective or osmotic roles in vivo, these proline analogues may be useful in chemotaxonomic investigations of Melaleuca species.

Mechanisms for drought resistance in early maturing cvar Flordastar peach trees

2011 ◽  
Vol 149 (5) ◽  
pp. 609-616 ◽  
Author(s):  
C. D. MELLISHO ◽  
Z. N. CRUZ ◽  
W. CONEJERO ◽  
M. F. ORTUÑO ◽  
P. RODRÍGUEZ
Keyword(s):  
Water Stress ◽  
Drought Resistance ◽  
Osmotic Adjustment ◽  
Prunus Persica ◽  
Field Studies ◽  
Passive Response ◽  
Early Maturing ◽  
Soil Water Conditions ◽  
Peach Trees ◽  
Response To Water

SUMMARYAdult early maturing peach trees (Prunus persica(L.) Batsch cvar Flordastar) grafted ontoP. persica×Prunus amygdalusGF-677 peach rootstock, were subjected to low water availability (water stress) and recovery periods for 28 and 7 days, respectively, during summer 2009. Control plants were irrigated daily at 1·3 estimated crop reference evapotranspiration (ETC) in order to obtain non-limiting soil water conditions. Active osmotic adjustment was observed at the end of the stress period. However, the magnitude of this osmotic adjustment (0·18 MPa) was not sufficient to modify the leaf water potential at turgor loss point. The observed active osmotic adjustment that maintained turgor was in contrast to other results in potted peach trees, where no osmotic adjustment was observed, and highlights the importance of field studies in which water stress is developed gradually over a prolonged period. Relative apoplastic water content (RWCa) values were high and decreased as a result of water stress. The rapid decrease in leaf conductance from the beginning of the stress period, together with the delay in stomatal reopening after rewatering, indicated that stomatal behaviour was not a simple passive response to water deficit. The results indicate that drought resistance in early maturing peach trees is based both on avoidance mechanisms, such as stomatal control and tolerance mechanisms, including active osmotic adjustment and high RWCa.

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