Accelerated aging in sorghum genotypes

The accelerated aging test has stood out among vigor tests. It has been used with different objectives, including as an assistance method in the selection of cultivars for plant breeding. This research aimed to analyze the effects of different exposure times to accelerated aging on the germination and vigor of sorghum seeds from different genetic sources. The experiment consisted of a completely randomized design with eight genotypes and four replications. Seeds were subject to an accelerated aging test with four exposure times (0, 24, 72, and 96 h) at a temperature of 47 °C and then evaluated by germination test (G), germination speed index (GSI), mean germination time (MGT), seedling emergence (SE), emergence speed index (ESI), and mean emergence time (MET). All genotypes presented a reduction in germination, GSI, SE, and ESI, and an increase in MGT and MET. The genotype CMX5156A had an increase in seed vigor under conditions of high temperature and relative humidity. Accelerated aging for 72 hours at 47 °C drastically reduces seed vigor. The accelerated aging test can be used to differentiate sorghum genotypes in breeding programs

AGRONOMICAL AND MOLECULAR EVALUATION OF ACCESSIONS FROM MAIZE CORE COLLECTION, SUBGROUP FLINT ENDOSPERM

The utilization efficiency of maize germplasm accessions that consist of a core collection can be incremented using molecular and morpho-agronomical characteristics, getting more detailed descriptions about these accessions. The objective of this work was to valorize maize core collection, sub-group endosperm flint of the Brazilian Agricultural Research Corporation (Embrapa), through the use of morphological descriptors and AFLP molecular markers. Fifty-eight accessions from the core collection were used, thirty-two morphoagronomical descriptors considered, and six AFLP primers combinations were tested to obtain the genetic patterns. The most contributions of morpho-agronomical variables for core collection genetic divergence were grain thousand weight (31.0%), ear height (21.7%) and ear weight (16.4%). The core collection principal component analysis was done with 14 morphoagronomical variables and indicated that variance accumulated by the first three components was 70.57%. The six primers AFLP combinations used in 58 accessions generated 207 bands, with 32.8 polymorphic bands average. Dendrograms of core collection showed similar general structure and did not indicate homogeneous group formation. The observed allele number average was 1.95, allele effective number average was 1.47 and the heterosigosity (h), (Nei’s index of genetic diversity) used for polymorphic information content evaluation was 0.28. Molecular characterization allowed valorization of each accession, indicating new information on the core collection genetic structure, and confirming high variability among accessions