Abstract:
In order to study of the effect of priming and salinity on physiological and chemical characteristics of wheat
(Triticum aestivum L.), an experiment was carried out at the Experimental Farm of Shiraz University. Results showed
that primed plants significantly reduced its gas exchanges by accelerating senescence under a series of salt stress,
which became more serious along with the increasing of salt concentrations, especially at 21 d after anthesis. Under
each level of salt stress, dry matter accumulation of primed plants was always higher than the non-primed plants.
Primed plants had higher potassium selectivity against sodium than non-primed plants with the former could maintain
relatively stable balance of ions, potassium/sodium was found not to be the limited factor for salt tolerant plants, but
it was in salt-sensitive plants. Net photosynthesis (Pn) significantly positively correlated with leaf potassium/sodium
(K+/Na+), relative water content (RWC), and leaf area duration (P < 0.01). So those four parameters might be ideal
criterions of salt tolerance in wheat. In conclusion, salt stresses caused significant declines in growth period of wheat
by accelerating leaf senescence at reproductive stage. Primed plants of wheat successfully preserved normal growth
by maintaining Pn, K+/Na+, leaf area duration (LAD) and dry matter accumulation (DMA), while non-primed plants
decreased considerably in those parameters. The improvement of photosynthesis and related traits in reproductive
stage was a key to the growth of wheat under saline conditions.
Machine summary:
The adaptability of plant species to high salt concentrations in soil by lowering tissue osmotic potential was accompanied by accumulation of these osmotic solutes (Zhu, 2002; Jaleel et al.
Seed priming techniques such as hydropriming, hardening, osmoconditioning, smohardening, and hormonal priming have been used to accelerate emergence of roots and shoots, more vigorous plants, and better drought tolerance in many field crops like wheat (Iqbal and Ashraf, 2007), chickpea (Kaur et al.
Net photosynthetic rate and stomatal conductance were measured on flag leaves of the primed and non-primed plants receiving different salt treatments at 7 d intervals after anthesis.
Effects of different levels of salinity stress on K+ in flag leaves of primed (pr) and non-primed (np) plants after anthesis However, the non-primed plants always decreased its leaf potassium content since anthesis, especially along with increases of salt concentrations.
Effects of different levels of salinity stress on Na+ content in flag leaves of primed (pr) and non-primed (np) plants after anthesis The primed plants maintained higher potassium/sodium ratios, but the non-primed plants decreased the ratios remarkably with increase of salt concentrations (Fig. 4).
The decreases of relative water content, leaf area index and leaf area duration in non-primed plants happened earlier than control under salt stress, which were linear with the days of the late of reproductive stage.
9%, these higher parameters of relative water content, leaf area index and leaf area duration were always noted in the primed plants at all levels of salt stress.
Farooq M, Basra SMA, Hafeez K, Ahmad N, 2005.