Abstract
ABSTRACT This study evaluated the effect of an organomineral fertilizer enriched with humic substances on soybean grown under water stress. The experiment was performed in a greenhouse using a Red Latosol (Oxisol) with adequate fertility as substrate, in which soybean plants were cultivated with and without water stress. The experimental design was randomized blocks, in a 2 x 5 factorial scheme (two moisture levels and five fertilizer doses: 0, 1, 2, 4 and 8 mL dm-3), totaling 10 treatments, with four replicates. The organomineral fertilizer was applied in the soil 21 days after plant emergence and the water regimes were established one week thereafter. The fertilizer was not able to attenuate the effects of water stress, reducing soybean grain yield by more than 50% compared with plants cultivated under no stress. Fertilizer doses caused positive response on soybean nutrition and grain yield and, under water stress condition, the most efficient dose was 5.4 mL dm-3. There were lower leaf concentrations of nitrogen, phosphorus and potassium and higher concentrations of sulfur in plants under stress. Humic substances favor the absorption of micronutrients.
Highlights
The increase in the contents of soil organic matter (SOM) improved physical, chemical and biological attributes and stimulated plant growth and development (Zandonadi & Busato, 2012; Baldoto et al, 2012; Canellas & Olivares, 2014; Zandonadi et al, 2014).Humic substances (HSs) are one of the main components of SOM
Many studies have shown the favorable effects of using these products, such as Nikbakht et al (2008), who applied in nutrient solution doses from 0 to 1000 mg L-1 of humic substances in Gerbera jamesonii plants, and Duplessis & Mackenzie (1983), who applied leonardite in area cultivated with corn, other studies report that the agricultural use of commercial HSs have no positive effects on plant development, since the applications depend on the origin of the material, method of extraction, concentration and composition of the humic extract
The experiment was set in a randomized block design, in 2 x 5 factorial scheme, which corresponded to two levels of soil moisture (90 and 30% of water holding capacity – Soil water holding capacity (SWHC)) and five doses of organomineral fertilizer enriched with humic substances (0, 1, 2, 4 and 8 mL per dm-3 of soil), with four replicates
Summary
The increase in the contents of soil organic matter (SOM) improved physical, chemical and biological attributes and stimulated plant growth and development (Zandonadi & Busato, 2012; Baldoto et al, 2012; Canellas & Olivares, 2014; Zandonadi et al, 2014).Humic substances (HSs) are one of the main components of SOM. The increase in the contents of soil organic matter (SOM) improved physical, chemical and biological attributes and stimulated plant growth and development (Zandonadi & Busato, 2012; Baldoto et al, 2012; Canellas & Olivares, 2014; Zandonadi et al, 2014). Many studies have shown the favorable effects of using these products, such as Nikbakht et al (2008), who applied in nutrient solution doses from 0 to 1000 mg L-1 of humic substances in Gerbera jamesonii plants, and Duplessis & Mackenzie (1983), who applied leonardite in area cultivated with corn, other studies report that the agricultural use of commercial HSs have no positive effects on plant development, since the applications depend on the origin of the material, method of extraction, concentration and composition of the humic extract. The development stage and the environment of the cultivated species interfere with the effect of HSs, the best results occur when they are used in soils with low contents of organic matter or when the plant is cultivated under stress conditions, whether nutritional or climatic (Hartz & Bottoms, 2010)
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