The Effect of Salinity on Growth, Inorganic Ions and Dry Matter Partitioning in Sugar Beet Cultivars

This study investigated intra-specific variation in the growth parameters and dry mat-ter partitioning of sugar beet cultivars at different levels of salinity (۰, ۵۰, ۱۵۰, ۲۵۰ and ۳۵۰ mM NaCl + CaCl۲ in ۵:۱ molar ratio) using four cvs, one British (Madison) and three Iranian cvs (۷۲۳۳-P۱۲, ۷۲۳۳-P۲۱ and ۷۲۳۳-P۲۹). The plants were grown in a controlled greenhouse environment for about ۱۸ weeks. Although growth parameters such as leaf area and dry matter accumulation were stimulated or unaffected at a low level of salinity (۵۰ mM), higher salt concentrations significantly decreased all growth traits. At a high level of salinity, cv P۲۹ showed a significantly higher leaf area and total dry matter than others at ۱۶ weeks of salt treatment. Pre-dawn leaf-water potential (ΨL) and shoot water content (SWC) were decreased by salinity. Cvs Madison and P۱۲ had significantly lower ΨL (more negative) and shoot water content at high levels of salt treatment (۲۵۰ and ۳۵۰ mM), while P۲۹ and P۲۱ showed higher ΨL (less negative) and shoot water content at the same salt concentrations. Analysis of ion accumulation revealed that Na+ and Cl- contents were greatly increased in leaves under saline conditions. However, salt tolerant P۲۹ had lower Na+ and Cl- concentrations than other cvs at high levels of salinity. The root dry matter of sugar beet cvs at the lowest and the highest salt concentrations reduced by ۲۳.۳% and ۸۹.۸%, respectively compared to the non-stressed plants, while shoot dry mat-ter decreased by ۱.۱% and ۷۷% at the same salt concentrations, respectively, after ۱۶ weeks of salt treatment. The pattern of dry matter partitioning to different parts of the plant was changed by salt stress and the dry matter allocated to the storage roots was re-duced by ۶% and ۱۸% at the lowest and the highest salt concentrations, respectively, at ۱۶ weeks after salinisation.

کلیدواژه ها:

Salinity ، Dry matter partitioning ، Growth ، Sugar beet