ABSTRACT Shade-tolerant soybean genotypes will allow their greater adoption for use in agroforestry or intercropped systems in tropical and subtropical regions. These genotypes can be obtained from the selection of existing superior genotypes or through breeding programs. This study, was verified such genetic variability and select those genotypes with cultivation potential at reduced levels of photosynthetically active radiation (PAR). Morphophysiological and yield characteristics of 16 soybean genotypes were evaluated in two experiments conducted in a controlled environment and laid in a randomized block design with three replications. Genetic parameters, correlations and genetic diversity were estimated and path analysis was performed. The soybean cultivars used showed genetic variability with a high variation index and heritability, which is advantageous for the selection of superior cultivars. Leaf area showed genotypic correlation and had a direct effect on seed weight per plant, regardless of shading. Additionally, the number of pods, hypocotyl diameter, and leaf area, all indirectly contributed to seed weight per plant regardless of shading. Seven genotypes (NS7780, NS8338, NS7667, NS7901, RK8115, CZ37B43 and 8579RSF) were selected based on genetic gain obtained by the Mulamba and Mock index at the two levels of PAR reduction tested. Furthermore, five of these genotypes (CZ37B43, RK8115, NS7901, NS8338 and 8579RSF) were identified by the Unweighted Pair-Group method Arithmetic Mean, as suitable either as a shaded crop or, as parental materials in breeding programs.

ABSTRACT present study aimed to determine the effects of different light restriction levels (shading levels) on soybean genetic parameters using a Bayesian multi-trait model (MTM) and select high-yielding soybean cultivars. Eighteen commercial soybean cultivars bred in a soybean breeding program were evaluated over two agricultural seasons. Three shading levels were used over two agricultural crop seasons, giving six treatments (light restriction × crop season). The experiments were arranged in a randomized complete block design with six treatments replicated thrice. The genetic values and parameters were estimated using a Monte Carlo Markov Chain algorithm. Broad-sense heritability range from 0.2093 to 0.7153. The lowest genotypic variance estimate was observed at the 45 % photosynthetically active radiation level in the 2019/2020 crop season year compared with that of other shading levels. Furthermore, a 40 % selection intensity had the highest soybean yield under different shading levels. The Bayesian MTM combined with the factor analysis and genotype-ideotype distance method can be used to evaluate and select soybean genotypes considering different shading levels. The soybean cultivars 8579RSF, NS8338, NS7901, NS7667, RK8115, and 8473RSF had higher genetic potential than other cultivars under different shading levels. multitrait multi trait (MTM highyielding high yielding seasons season. . season) thrice algorithm Broadsense Broad sense 02093 0 2093 0.209 07153 7153 0.7153 4 20192020 2019 2020 2019/202 Furthermore genotypeideotype genotype ideotype 8579RSF RSF NS8338 NS NS7901 NS7667 RK8115 RK 0209 209 0.20 0715 715 0.715 2019202 201 202 2019/20 NS833 NS790 NS766 RK811 020 20 0.2 071 71 0.71 201920 2019/2 NS83 NS79 NS76 RK81 02 2 0. 07 7 0.7 20192 2019/ NS8 NS7 RK8