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Influence of humic acid molecular fractions on growth and development of soybean seedlings under salt stress

Matuszak-Slamani, Renata, Bejger, Romualda, Cieśla, Jolanta, Bieganowski, Andrzej, Koczańska, Magdalena, Gawlik, Andrzej, Kulpa, Danuta, Sienkiewicz, Mariola, Włodarczyk, Małgorzata, Gołębiowska, Dorota
Plant growth regulation 2017 v.83 no.3 pp. 465-477
Glycine max, chlorophyll, cultivars, diffusivity, electrophoresis, fen soils, humic acids, iron, leaf area, microfiltration, roots, salt stress, seedlings, shoots, sodium chloride, soybeans, zinc
In the present study, the influence of humic acid (HA) molecular fractions (HA < 30 kDa and HA > 30 kDa) on enhancing the tolerance of seedlings of soybean [Glycine max (L.) Merr.] Progres and Nawiko cultivars to salt stress (50 mM NaCl) was investigated. HA were extracted from mountain fen soil and then were separated into two molecular fractions by membrane filtration and characterized by diffusion coefficient (Dₐₚₚ), electrolytic conductivity (κ) and electrophoretic mobility (Uₑ). The following biometric parameters of tested plants were determined: total leaf area, height of plants, fresh and dry mass of the over ground part and roots as well as length of shoots cells and length of stomas. The chlorophyll content in ground tissue as well as the macro and microelements content in tested plants also were determined. The results showed that the κ, Uₑ and Dₐₚₚ for HA > 30 kDa were lower than these for HA < 30 kDa. Adding NaCl caused increase κ and decrease Dₐₚₚ and Uₑ. The salt stress caused a major decrease in biometric parameters in tested plants. HA > 30 kDa reduced the uptake of macro and microelements in the soybean Progres cultivar. In soybean Nawiko cultivar, it caused significant uptake of Fe and Zn. Soybean cultivars showed strong reaction to salt stress. HA molecular fractions reduced or eliminated the influence of the salt stress. However, HA > 30 kDa was more effective than HA < 30 kDa, due to its properties.