Screening of Soybean Genotypes for Waterlogging Stress Tolerance and Understanding the Physiological Mechanisms

Waterlogging is a common form of abiotic stress that severely impedes global soybean production. Targeting this issue, an experiment was carried out at Sher-e-Bangla Agricultural University during August–November 2019 to screen out the waterlogging tolerance and yield performances of selected soybean genotypes. The experiment was laid out in a completely randomized design (CRD) with three replications consisting of 2 water levels (control and waterlogging) and 12 genotypes (Sohag, BARI Soybean-5, BINAsoybean-1, BINAsoybean-2, BINAsoybean-3, BINAsoybean-5, BINAsoybean-6, SGB-1, SGB-3, SGB-4, SGB-5, and GC-840). On the 15th day after sowing, plants were exposed to waterlogging for 12 days. Waterlogging remarkably declined the growth and yield of all the soybean genotypes compared to control. Reduced plant height, relative water content, above-ground fresh and dry weight, SPAD value, leaf area, number of leaves, branches, pods, seeds pod−1, 100-seed weight, and seed yield plant−1 were observed under waterlogging stress. Conversely, mortality rate and electrolyte leakage were increased under the same condition. The waterlogged plants showed delayed flowering and maturity compared with the control plants. However, among the 12 genotypes, Sohag, BARI Soybean-5, GC-840, BINAsoybean-1, and BINAsoybean-2 showed better waterlogging tolerance. These genotypes showed a greater number of adventitious roots in the base of their stem, which probably helped plants to thrive under waterlogging conditions.

Biofertilizers in the control of Pratylenchus brachyurus in soybean crop

Nematodes are of great importance in soybean cultivation, especially the Pratylenchus brachyurus known as root lesion nematode. Its attack on plant roots causes less efficiency in the absorption of water and nutrients, in addition to damaging the plant's development. There is still no fully efficient method to control this phytopathogen, however, some products are available on the market, including biological control. Thus, the aim of this study was to evaluate commercial biological products in the efficiency of reducing the nematode population in soybean crop in Goiás, Brazil. The design was completely randomized in a 2x4 factorial scheme, the first factor being two soybean genotypes (Brasmax Bônus and Nidera NS 8383) and the second factor the treatments consisting of different dosages in an association of three commercial products: No-Estio®, Bio-fertility® and Radic®. The treatments used were: T1 control - without application of the products; T2 half the recommended dose; T3 the recommended dose and T4 a dose and a half that recommended by the manufacturer. Plant evaluation was carried out after 75 days of nematode inoculation. The results obtained showed that both cultivars hosted P. brachyurus, however, the treatments using the products had a lower population density of this nematode. It was concluded that the two soybean cultivars are hosts of Pratylenchus brachyurus. The agronomic character plant height was more affected when there was no application by the biological method. The association of No-Estio®, Bio-fertility® and Radic® products reduced the population density of nematodes in infected plants.

Assessment of Soybean Resistance Level to Pod Sucking Bug Riptortus linearis F. (Hemiptera: Coreidae) based on No-choice and Free-choice Tests

Background: The infestation of the pod sucking bug Riptortus linearis is one of the limiting factors of soybean productivity in Indonesia. The research aims were to identify the level of resistance to the pod sucking bug R. linearis on several soybean genotypes based on the no-choice test (NCT) and free-choice tests (FCT). Methods: The genetic materials used were 49 soybean genotypes. The study was conducted in the Indonesian Legumes and Tuber Crops Research Institute (ILETRI) from August to December 2020, using the randomized block design in triplicates. The evaluation for pod sucking bug resistance was based on NCT and FCT. Result: The FCT resulted in two genotypes with a consistent moderately resistance level (20-40% of damage intensity) to pod sucking bug based on the pod and seed damage intensity. The NCT method resulted in five genotypes as moderately resistant (20-40% of damage intensity) to pod sucking bug based on the seed damage. The NCT resulted in higher average intensity of pod and seed damage (80.25% and 71.23%, respectively) than the FCT (69.91% and 69.09%, respectively). Two soybean genotypes (Degra/Anjasmoro-1-559 and Anjasmoro/IAC100-2-618) with a consistent moderately resistance level could be used for cultivar improvement in the breeding program. The pod trichome density was suggested to be one of the effective morphological defenses against the pod sucking bug attack.

Screening of Soybean Genotypes Based on Root Morphology and Shoot Traits Using the Semi-Hydroponic Phenotyping Platform and Rhizobox Technique

Root-system architecture is vital for improving soybean (Glycine max L.) growth and nutrient uptake. We characterised root-system architecture and shoot traits of 30 soybean genotypes in a semi-hydroponic system 35 days after sowing (DAS) and validated eight genotypes with contrasting root-system architecture in 1.5 m-deep rhizoboxes at the flowering stage. Among them, two genotypes were selected for evaluation through to maturity. Abundant variation (coefficient of variation values ≥ 0.25) was observed in 11 of 13 measured roots and shoot traits during the early growth stage. After late growth stages, strong positive correlations were found between root traits and shoot traits, except for specific root length and diameter. Seed yield and yield traits at final harvest significantly differed between two contrasting soybean genotypes. The large-rooted genotype had a higher harvest index than the small-rooted genotype. Soybean genotypes with larger root systems had a long time to flowering than those with smaller root systems. Genotypes with large-root systems had 106% more leaf area, and 245% more shoot dry weight than those with small systems, presumably due to high canopy photosynthesis to supply the demand for carbon assimilates to roots. Total root length, and root: shoot ratio-traits data collected in the rhizobox study, strongly correlated with the same traits in the semi-hydroponic phenotyping system. We found genetic variation and phenotypic plasticity in other root and shoot traits such as taproot depth, root dry weight, specific root length, and average root diameter among the tested genotypes. Phenology, particularly time to flowering, was associated with root system size. Some root and shoot traits in the semi-hydroponic phenotyping system at the seedling stage produced similar rankings at the later phenological (flowering) stage when grown in the soil-filled rhizoboxes. The soybean genotypes characterised by vastly different root traits could be used for further glasshouse and field studies to improve adaptation to drought and other specific environments.

Search of the new SSR-loci of DNA for development of effective technology for soybean genotyping

Soybean is the major protein-oil crop of a huge economic importance. Currently, to describe the new cultivars being applied for a patent there are used the modern methods based on an analysis of microsatellite (SSR) loci of DNA. The purposes of this work were a search of the new microsatellite markers to optimize the existing technology of soybean cultivars certification and identification as well as selection of conditions for PCR analysis and to test them on cultivars from the VIR’s collection. Seven microsatellite loci demonstrated the high polymorphism level on soybean cultivars and located in the different chromosomes were chosen in the literary sources and librarian data bases. The optimal temperatures for annealing were selected empirically for all the pairs of SSR-markers. The results of DNA amplification of 20 soybean genotypes showed all seven studied SSR-loci were polyallel. In general, we revealed 22 alleles that on average are 3.1 per a locus. The effective number of alleles Ne for the studied soybean genotypes varied from 1.69 to 2.27 and on average was equal to 2.01. An average meaning of an index of the polymorphic information content (PIC) was 0.50. All the investigated soybean samples have the unique sets of alleles by the studied loci. Seven approbated loci can be used in development of an effective technology for identification and certification of the soybean genotypes.

EFFECT OF ELECTROSTATIC FIELD ON SOYBEAN SEED GERMINATION PARAMETARS

The aim of this study was to examine the influence of electrostatic fields on seed vigor, mean rate of germination and coefficient of velocity of germination of five soybean genotypes. Testing was conducted at the Novi Sad Institute of Field and Vegetable Crops on the seeds of five soybean varieties: Sava, NS 2024, NS 1347, NS 3127, and NS Blackstar. The seeds were exposed to different values of direct current (DC) of the following voltage: 0 V (control), 3 V, 6 V and 9 V, to which the seeds were exposed for 0 min (control), 1 min and 3 min. After exposing the seeds to the electric field, the vigour index (VI), mean rate of germination (MGR) and coefficient of velocity of germination (CVG). The results show that the effect of the electrostatic field on seed vigour, mean rate of germination and coefficient of velocity of germination depends on the genotype, voltage and exposure time. The application of DC can be a suitable method for improving vigour index (VI), mean rate of germination (MGR) and coefficient of velocity of germination (CVG). In addition, the results indicate that it is necessary to adjust the DC treatment (voltage and duration of exposure of seeds) to a particular genotype, since inadequate treatments may deteriorate the quality of seeds. Keywords: electrostatic field, vigor index, MGR, CVG, soybean