Artificial hybridization in Phaseolus lunatus L. is still little used in genetic improvement programs in Brazil due to the low establishment percentages. This work aimed to evaluate pollen viability and stigma receptivity in different Lima bean genotypes throughout the day. Accessions 'Roxinha -MT' and 'Cana Longa-PB' were used in the experiment. Five flower buds were collected from each genotype at 6:00 a.m., 10:00 a.m., 2:00 p.m., and 6:00 p.m. The stigma receptivity was determined using 3% hydrogen peroxide, whereas pollen viability was determined with 2% acetocarmine colouration. The genotype and time factors acted independently on the percentage of viable and non-viable pollen grains and stigma receptivity. The genotype 'Roxinha' presented 88.54% viable pollen grains, a value 84.27% higher than that of the 'Cana Longa' genotype. This percentage varied as a function of time, with the highest means observed at 6:00 a.m. Stigma receptivity was influenced only by the time of the day, undergoing a great reduction in receptivity, from 88% in the early morning to slightly more than 40% around noon. These results indicate that 6:00 a.m. is the most suitable time to perform artificial crosses in Lima bean plants.
The landrace varieties used in breeding programs need to have well-determined and recognized phenotypic characteristics. The guarantees in terms of productivity in the next cycles go through an evaluation of the quality of the seeds. The objective of this study was to evaluate whether lima bean accessions differ in tegumental pattern and physiological seed quality and the relationship between the traits and to select the superior lima bean genotype for seed quality. Seeds of ten accessions (criole varieties) of lima bean (Phaseolus lunatus) produced in the seed multiplication field were used. The seeds were kept in plastic bottles until evaluation. A completely randomized design was used with 10 treatments (accessions) and 15 replicates (seeds) for the pattern analyses and four replicates of 50 seeds each for the germination and vigor tests. The pattern, germination and vigor of the seed lots of the breeding program depend on the accession (p < 0.05). The accessions presented seeds from small to large, with a shape varying from flat to rounded. The accessions CPCE 020, UFPI 1266 and UFPI 1294 had a satisfactory percentage of twinning, above 70%. However, the UFPI 1204 accession also had the greatest vigor. A positive correlation was observed between seed size and germination percentage, which should be considered in indirect selection within breeding programs.
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