Abstract
ABSTRACT Biostimulants currently available on the market include those containing seaweed extract. There is sufficient scientific evidence to conclude that applying biostimulants to agricultural crops can positively impact plant growth and yield. However, results differ between plants species and environmental conditions. As such, the present study aimed to assess the effects of doses and application times of a biostimulant based on seaweed (Ecklonia maxima) extract on the morphology and yield of soybean crops. The experiment was conducted in a field in the municipality of Uberaba, Minas Gerais state (MG), Brazil, in dystrophic red latosol. A randomized block design was used, with four repetitions, in a 3 x 5 factorial scheme consisting of three application times (phenological growth stages: V4, R1 and V4+R1) and five doses of foliar -applied biostimulant (0, 250, 500, 750 and 1000 mL ha-1). In general, biostimulant application influenced the number of branches, nodes, flowers, and pods on the soybean plants and, consequently, crop yield. A dose of 607 mL ha-1 promoted a 6.1% greater grain yield (5379 kg ha-1) than that obtained without biostimulant spraying (5070 kg ha-1). Application in stage R1 resulted in plants with more flowers and pods.
Highlights
Adequate flowering is important in soybean crops since it ensures a large number of pods and, high yields
Given that abortion occurs in the early growth stages, not all flowers and pods remain on the plants and produce grain
Adverse physiological reactions due to environmental stress can alter the availability of photoassimilates and nutrients, as well as the concentration of plant hormones such as abscisic acid and cytokinin, which are essential in controlling the fixation of soybean reproductive structures (LIU; JENSEN; ANDERSEN, 2004)
Summary
Adequate flowering is important in soybean crops since it ensures a large number of pods and, high yields. Given that abortion occurs in the early growth stages, not all flowers and pods remain on the plants and produce grain This is a natural process that occurs even under ideal conditions, several factors influence the severity of flower and pod abortion, including environmental stress (THOMAS, 2018). Auxins influence the number of reproductive structures on plants because they accumulate in developing pollen grains, likely promoting pollen germination on the stigma and triggering the rapid growth of pollen tubes (ALONI et al, 2006). These plant hormones can be found in some products of biological origin, such as seaweed-based biostimulants (STIRK et al, 2004), which may affect flower and pod fixation
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