M. Mohammad et al., TOMATO ROOT AND SHOOT RESPONSES TO SALT STRESS UNDER DIFFERENT LEVELSOF PHOSPHORUS-NUTRITION, Journal of plant nutrition, 21(8), 1998, pp. 1667-1680
Crops differ in their ability to grow under saline conditions and thei
r responses are quite variable and not fully understood. This study wa
s conducted to evaluate the root and shoot responses of tomato to salt
stress conditions under different levels of phosphorus (P) nutrition.
Tomato seedlings (cv Riogrande) were grown in 500 mt glass jars conta
ining Hoagland's solutions which were salinized by four levels of NaCl
salt (0, 50, 100, and 150 mM NaCl) and/or enriched with three P level
s (0.5, 1, and 2 mM P) making nine combination treatments. Plants were
harvested at the vegetative growth stage and data were collected for
root and shoot characteristics. The results indicate that increasing s
alinity stress was accompanied by significant reductions in shoot weig
ht, plant height, number of leaves per plant, and a significant increa
se in leaf osmotic potential and peroxidase activity regardless of the
level of P supplied. Both root length and root surface area per plant
were decreased significantly under higher salinity conditions at all
levels of phosphorus. On the other hand, increasing the phosphorus lev
els enhanced root growth through increasing both root length and root
surface area. This phenomenon was observed at all levels of salinity.
It can be concluded that root morphology parameters and peroxidase act
ivity are additional sensitive parameters which are affected by salt s
tress and, therefore, can be employed as a criteria for monitoring pla
nt response mechanisms to salt stress conditions.