effects of desiccation, nacl and polyethylen glycol induced water potentials on the sprouting of glycyrrhiza glabra rhizome buds

the effects of desiccation and nacl and polyethylen glycol (peg) induced water potentials on rhizome bud sprouting of the perennial weed, glycyrrhiza glabra were investigated in separate laboratory experiments laid out in completely randomized designs. each treatment was replicated four times. the water potentials of nacl and peg used were 0, -0.4, -0.8, -1.2 and -1.6 mpa. desiccation experiments were conducted in factorial arrangements of treatments. factors included two classes of rhizome diameter, thin (rhizome specific weight 0.05-0.4 g cm-1) and thick (rhizome specific weight of 0.4-1.6 g cm-1) and desiccation duration (exposing rhizome fragments to sunlight) of six levels (0, 6, 8, 12, 24 and 48 h). there were no significant differences between 0 and -0.4 mpa of peg solutions. nacl treatments from -0.4 to -1.2 and peg treatments from -0.8 to -1.6 mpa drastically reduced rhizome bud sprouting and its rate. no bud sprouting was observed in –1.2 and –1.6 mpa of nacl solution. for all treatments, nacl was found to be more inhibitory than corresponding potentials of peg solution. this correspondence to: n. nezamabadi; [email protected] n.nezamabadi et al. 42 can be attributed to the toxicity of nacl ions. no bud survived after 48 and 36 hours desiccation in thick and thin rhizomes, respectively. complete inhibition of sprouting occurred when rhizomes were desiccated to 42% and 70% of their original weight for thick and thin rhizomes, respectively.