Abstract
To understand the differential effect of moderate salinity on the growth and ion contents in mainstem and subtillers of wheat plants, two spring wheat (Triticum aestivum L.) genotypes (Sakha 8 and Thasos) were grown in a greenhouse in soil with or without salinity. Both the above-ground dry weight and the leaf area at day 55 after sowing, as well as the grain yield, grain number, spikelet number, straw dry weight and above-ground dry weight at plant maturity, were determined. Inorganic ion content in young leaves at day 55 after sowing was also analyzed. The results showed that the above-ground dry weight and leaf area in the subtillers (T1 and T2) at day 55 after sowing were greatly reduced by salinity. Compared with the effect of salinity on subtiller growth, the mainstem was much less affected during the vegetative growth stages, whereas there was a similar effect of salinity on the grain yield between the mainstem and subtillers. The reduction in the grain yield of Sakha 8 by moderate salinity mainly resulted from a decrease in the number of tillers, whereas in addition to a reduction in the number of tillers in the salt-sensitive genotype Thasos, the grain yield in mainstem and subtillers was further reduced during the grain filling. Both wheat genotypes are more sensitive to salt stress during the vegetative growth stages than in the reproductive stages. The salt-tolerant genotype Sakha 8 is characterized by the exclusion of Na
+
in the leaves. Thus, under moderate saline conditions the greater reduction in subtillers may result from an ion imbalance in the salt-tolerant genotype Sakha 8 and from Na
+
toxicity in the salt-sensitive genotype Thasos.