Effect of temperature, light and salinity on seed germination and radicle growth of the geographically widespread halophyte shrub Halocnemum strobilaceum.
OBJECTIVE
The small leafy succulent shrub Halocnemum strobilaceum occurs in saline habitats from northern Africa and Mediterranean Europe to western Asia, and it is a dominant species in salt deserts such as those of north-west China. The effects of temperature, light/darkness and NaCl salinity were tested on seed germination, and the effects of salinity were tested on seed germination recovery, radicle growth and radicle elongation recovery, using seeds from north-west China; the results were compared with those previously reported on this species from 'salt steppes' in the Mediterranean region of Spain.


METHODS
Seed germination was tested over a range of temperatures in light and in darkness and over a range of salinities at 25 degrees C in the light. Seeds that did not germinate in the NaCl solutions were tested for germination in deionized water. Seeds from which radicles had barely emerged in deionized water were transferred to NaCl solutions for 10 d and then back to deionized water for 10 d to test for radicle growth and recovery.


RESULTS
Seeds germinated to higher percentages in light than in darkness and at high than at low temperatures. Germination percentages decreased with an increase in salinity from 0.1 to 0.75 M NaCl. Seeds that did not germinate in NaCl solutions did so after transfer to deionized water. Radicle elongation was increased by low salinity, and then it decreased with an increase in salinity, being completely inhibited by > or = 2.0 M NaCl. Elongation of radicles from salt solutions < 3.0 M resumed after seedlings were transferred to deionized water.


CONCLUSIONS
The seed and early seedling growth stages of the life cycle of H. strobilaceum are very salt tolerant, and their physiological responses differ somewhat between the Mediterranean 'salt steppe' of Spain and the inland cold salt desert of north-west China.
Qu
Xiao-Xia
XX
Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China.
Huang
Zhen-Ying
ZY
Baskin
Jerry M
JM
Baskin
Carol C
CC
D027703:Amaranthaceae / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects*; D000704:Analysis of Variance; D018525:Germination / Q000187:drug effects / Q000528:radiation effects*; D008027:Light; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development*; D054712:Salinity; D012639:Seeds / Q000187:drug effects / Q000528:radiation effects*; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D014867:Water
D014867:Water; D012965:Sodium Chloride