Mateus Ribeiro Piza

The aim of this study was to select soybean cultivars adapted to Mozambican farming systems using participatory and conventional breeding and to assess the extent of agreement between these approaches. Experiments were conducted in the Zambézia and Tete provinces during the 2021/22 growing season in a randomized complete block design with 41 genotypes and three replications. In the participatory plant breeding approach, 165 farmers participated in the selection process. The top 35 cultivars for each method were identified and then compared using a coincidence index, which resulted in -29.41, confirming the divergence. The cultivar TGX 2002-3DM was ranked highest in the conventional method, whereas TGX 2014-16FM was selected by farmers. These findings indicate the need to incorporate farmers’ preferred traits in selecting varieties in the breeding process to increase the likelihood of adoption of the varieties. These results support the hypotheses proposed in this study.

Currently, the demand is not only for more productive corn hybrids, but also for those with high physiological seed quality. Seed quality is considered the sum of genetic, physical, physiological and sanitary attributes that directly interfere in plant vigor. The objective of this study was to evaluate the physiological parameters of the seeds of parents and maize inter varietal hybrids obtained in a reciprocal recurrent selection program through physiological and image analysis techniques and either to study the feasibility of simultaneously selecting for seed physiological quality and grain yield. Two experiments were performed, one in the field and the other in the laboratory. The evaluated traits in the field were days of female flowering, days of male flowering, insertion of the 1^st ear, plant height and grain yield. For the physiological quality, the attributes of germination at four days, germination at seven days, vigor by the cold test, emergence speed index, and the ratio of the root length to shoot length were obtained using GroundEye®. Heterosis was measured for the agronomic and physiological traits. Through the contrast between the inter varietal crosse hybrids and reciprocals we measured the maternal effect. The magnitudes of heterosis allowed us to infer that as greater as the number of selection and recombination cycles, on average, greater heterosis for the traits grain yield and seed germination. The correlated response indicated that, high yield intervarietal hybrids have better seed physiological quality.

Soybean is the most cultivated oilseed crop in the world, with much of the merit obtained in recent years due to genetic improvement in which greater genetic progress can be obtained by improving physiological characteristics, which result in a greater impact on yield. Color spectra can be good indicators of the physiological quality of plants by quantifying the intensity of colors in the RGB spectra, being a non-destructive method that allows optimizing the collection and the number of data. We aimed to identify differences in spectral reflection between conventional, transgenic RR1 and RR2 soybean cultivars under the effect of glyphosate herbicide. The plants were cultivated in five-liter pots in a greenhouse in a randomized block design, following cultural treatments recommended for the soybean crop. Leaves of plants in vegetative stages V1 or V2 were collected and duly identified to compose a second experiment, being then submitted to incubation in plastic trays in which the treatments were organized in a completely randomized design in a 6×6 factorial scheme, with three replications. Glyphosate herbicide doses (0.0, 0.03%, 0.06%, 0.12% and 0.24% AE/ha) were added to the leaf petiole on a cotton pad in order to maintain constant contact with the respective dose. The trays were kept under ambient conditions for 14 days after incubation under 16h-light and 8h-dark of artificial light. Images were collected with a smartphone camera on the 13th day after leaves collection (DAC) in an appropriate studio to maintain adequate lighting, and on the 14th DAC SPAD index data were collected in three locations on the leaf, avoiding the midrib. The images were cropped and then segmented using manual thresholding in which the average values for the red, green and blue channels were extracted. The Excess Red Index (ExR) was calculated using the red and green channels data. The data obtained were analyzed and the significant effects of the model were analyzed by the Skott-Knott test for the cultivar factor and regression models were adjusted for the dose factor. Spearman’s correlation was used to verify the relationship between the studied variables. In view of our results, glyphosate affects the chlorophyll of resistant plants when subjected to continuous exposure and at high doses, leading to senescence and that the red channel information can be used to infer the level of interference in the photosynthetic activity of plants subjected to the herbicide.