Phosphorus translocation in salt-stressed cotton

Abstract

1991. Phosphorus translocation in salt-stressed cotton. -Physiol. Piant. 83: 627-^32.The effect of salinity on plants has usually been studied at high inorganic P concentration ([Pi]) in the nutrient solution, and salinity x Pi interactions have been examined at much higher [Pi] than found in soil solutions. Short-term ^^Fi experiments were carried out to study the effect of salinity (150 mM NaCl) on phosphorus translocation in cotton plants (Gossypium hirsutum L. cv. Acala SJ-2) grown in nutrient solutions containing 10 \iM [Pi]. The effect of additional Ca to a concentration of 10 mM was also tested. Salinity inhibited '^P translocation from root to shoot. This inhibition was more evident at higher [Pi] in the root medium. Increasing [Pi] 33-fold in the solution resulted in a 4.3-fold increase in [^"P| in the root under saline conditions, but only in a 1.8-fold increase in the shoot. In older shoot tissues total [Pj was elevated in the salinized plants. In the young tissues, however, total P concentration was higher in control plants. Inhibition of ^*P translocation by salinity was greater from root to young leaves than to mature shoot tissues. Salinity also decreased '^P recirculation from the cotyledons to the young leaf. Inhibition by salinity of both '-P translocation and recirculation to young leaves was fully reversed by increasing Ca supply from 1 to 10 mM.

Salt‐induced inhibition of phosphate uptake in plants of cotton (Gossypium hirsutum L.)

“…These results indicate that there was an inhibition of^P transport from the cortex to the tips and from the root to the shoot due to the salt treatment. These data are in agreement with our previous result (Martinez & Lauchli, 1991) which indicated that high salt inhibited recirculation of ^^P in cotton plants. However, in the low salt plants the tip acted as a sink importing ^^P from other parts of the roots; in the high salt treatment the [PJ in the tips decreased, and part of '^P absorbed in the first 10 min was exported to other parts of the plant.…”

Salt‐induced inhibition of phosphorus transport in lettuce plants

“…Exposure to NaCl salinity affects transport processes in the plant, the result of which can be an alteration of tbe nutritional status and tissue ion imbalance (Lauchh and Epstein 1990), Salt stress inhibits the uptake and transport of K* (Lynch and Lauchli 1984), Ca^* (Lynch and Lauchli 1985), N (Aslam et al, 1984), and P (Martinez andLauchli 1991, 1994), However, the effect of salinity on the nutritional status of phosphorus in the plant is still controversial. On the one hand, leaf injury under saline and high phosphate regimes (tnM range) has been interpreted as P toxicity induced by salinity (Bernstein et al, 1974, Cerda et al, 1977, Grattan and Maas 1985, Nieman and Clark (1976) sbowed that salinizing com plants at high Pi concentration (2 mM) resulted in P, accumulation and toxicity.…”

“…On the other hand, at a moderate Pj coticentration (0,1 tnAf), salinity led to a reduced Pj content of mature leaves. In studies carried out under low P, regimes, Awad et al, (1990) demonstrated an increase in tbe salt tolerance of tomato plants in response to elevated P, concentrations, Retranslocation of P| within tbe intact plant plays an important roie in maintaining the nutritional status of P( in young tissue (Bieleski and Ferguson 1983), Working with the relatively salt-tolerant cotton plant at 10 (lM P, Martinez and Lauchli (1991) found that salinity inhibited the translocation of P; from the root to the shoot. Salinity also reduced Pf recirculation from old to young tissue.…”

Effects of salinization on nutrient transport to lettuce leaves: consideration of leaf developmental stage

“…In Lupinus luteus [P] decreased 17 % in young leaflets 16 d after salinization to 50 mM NaCl, although increases in [P] were documented after an additional week of salinization (Treeby & Steveninck, 1988). In small Gossypium hirsutum leaves 3 h transport of $#PO % − decreased 24 % after an 8 d salinization (Martinez & Lauchli, 1991). Transport of $#PO % − (3 h pulse and 3 h chase) was inhibited up to 57 % in the youngest leaves of L. sativa after moderate salinization (0.1 mM PO % − and SAR of 41 (Martinez et al, 1996)).…”

“…Most studies investigating a NaCl-induced nutritional disturbance have focused on excesses of Na + and Cl − and when nutrients have been included, this has most often been limited to K + (Lazof & Bernstein, 1999). None the less, NaCl-disturbed nutrient supply has been suggested for nutrients other than K + , for example Ca# + (Wieneke & Lauchli, 1980 ;Grieve & Fujiyama, 1987 ;Maas & Grieve, 1987 ;Bernstein et al, 1995) or PO % − (Grattan & Maas, 1984 ;Martinez & Lauchli, 1991). In studies of ' K : Na competition ' it has often been difficult to evaluate the extent to which mineral osmotica were advantageously substituted (Na + for K + ) and the extent to which growth was compromised by accumulation of ' toxic ' levels of Na + or Cl − .…”