Does the substrate affect the germination of soybean seeds treated with phytosanitary products?

Abstract

The use of an appropriate method that accurately expresses physiological seed quality and minimizes possible phytotoxicity by chemical products in laboratory testing with soybean seeds is relevant. The objective of this work was to evaluate the influence and infer the method adequacy for the representative evaluation of physiological quality of soybean seeds treated with phytosanitary products. Two experiments were carried out in a completely randomized design, with trial 1 in a 9×5 factorial scheme involving nine seed treatments, including fungicides and insecticides, and solutions with five osmotic potentials (0, -0.25, -0.5, -0.75 and -1.0 MPa) for wetting a paper substrate in a germination experiment, with evaluation of the normal seedlings at five and eight days after sowing. The second experiment consisted of a 9×7 factorial, with nine seed treatments and seven methods for germination evaluation at 5 days (between paper - BP, between sand - BS, between paper with water restriction - BPWR, between paper with preconditioning - BPC, sand between paper - SBP and vermiculite between paper - VBP). Treatments with insecticides affect seedling germination and evaluation, with greater phytotoxicity in relation to fungicides. Methods with readily available water led to greater phytotoxicity than methods with low water availability. For soybean germination evaluation of seeds treated with phytosanitary products, the BPC, SBP and VBP methods were optimal.

Phytotoxicity in soybean seeds treated with phytosanitary products at different application times

“…Nevertheless, regardless of the time of application, the germination test showed that seeds treated with the insecticides Cropstar®, Cruiser®, and Pirâmide® had a lower percentage of normal seedlings than the seeds treated with the other products, which confirms that some insecticide molecules can show toxicity in physiological analyses, especially in a paper substrate (Brzezinski et al, 2015;Ferreira et al, 2016;Santos et al, 2018). Rocha et al (2020) observed that the treatments of soybean seeds with insecticide molecules affect germination and seedling evaluation, with greater phytotoxicity in relation to fungicide molecules, especially in analysis methods with abundant and readily available water.…”

“…Germination under water restriction (GH): performed according to the method described above for the germination test; however, an aqueous solution containing mannitol (P.A C6H14O6 -M.W. 182.17) was used to moisten the germination paper for artificial simulation of water restriction and to obtain osmotic potential of -0.25 MPa (Rocha et al, 2020). Four (4) replicates of 50 seeds were used for each block.…”

“…Ferreira et al (2016) found that the mixtures of some insecticides hurt the physiological quality of treated soybean seeds after two months of storage. According to Rocha et al (2020), treatments of soybean seeds with insecticide molecules affect the germination and evaluation of the seedlings, and have greater phytotoxicity than fungicide molecules.…”

Physiological and enzymatic monitoring of treated seeds of cultivars soybean during storage

“…Del Bem Junior et al ( 2020) also observed lower physiological quality after storage in soybean seeds treated with the insecticide thiamethoxam. According to Rocha et al (2020), insecticidal molecules hinder soybean germination and may cause greater seed phytotoxicity than fungicides.…”

“…Physiological quality must be maintained until sowing, so the period between seed field production and sowing, i.e., storage, is relevant. During storage, several factors are important, including environmental conditions (Smaniotto et al, 2014), genotype (Carvalho et al, 2014a), and the composition and volume of solution in the treatment (Santos et al, 2018), especially when insecticidal molecules that have a greater tendency for toxicity than fungicides are used (Rocha et al, 2020). Monitoring the time that the soybean seed can remain treated without impairing its physiological quality, the "seed safety", is extremely important (Carvalho et al, 2020).…”