Exogenously applied silicate and abscisic acid ameliorates the growth of salinity stressed wheat (Triticum aestivum L) seedlings through Na + exclusion

摘要

Hydroponic experiments were conducted to investigate the possible role of abscisic acid (ABA) and silicate (Si) on inducing salinity tolerance in wheat seedlings. Caryopses of two wheat genotypes Kharchia-65 (salt tolerant) and Punjab-85 (salt sensitive) were pre- treated with ABA (10 m M) for 24 h. Ten-day-old seedlings were exposed to 100 mM NaCl solution containing either 0 mM or 3 mM of sodium silicate for 16 days. We employed a fluorescent tracer trisodium salt of 8-hydroxy-1, 3, 6-pyrenetrisulphonic acid (PTS) for estimating Na+ transport pathway to shoot. Exogenously applied Si as alone or with ABA significantly improved seedling growth by inhibiting Na+ transport and the Na/+K+ ratio in both wheat genotypes. The genotype Punjab-85 maintained higher apoplastic Na+ concentration compared to Kharchia-65 under NaCl treatment. Moreover, Si and ABA application improved leaf chlorophyll contents and consequently net assimilation rate of NaCl- stressed wheat seedlings through up-regulation of antioxidative enzyme activities. The results suggested that application of Si alone or in combination with ABA can significantly limit Na+ bypass flow in both salt sensitive and tolerant wheat genotypes; however, ABA alone was effective in sensitive genotype only (Punjab-85). It is inferred from the results that Si had a more prominent role than ABA on plants in increasing biomass accumulation, proline contents and antioxidant enzyme activities, and inhibiting Na+ accumulation and bypass flow. Nevertheless, ABA assisted Si in the amelioration of salt stressed in much better way than Si alone.