ABSTRACT Guava is of great economic importance in Brazil. The development of new cultivars by obtaining inbreeding lines has been a promising option. The objective of this work was to evaluate the S2 families of Psidium guajava using seed attributes. Different characters of physiological quality of guava seeds were studied, in addition to performing digital phenotyping of characteristics of geometry, texture and colors of the seeds. The variables were analyzed simultaneously using the Ward-Modified Location Model (MLM) method and carried out individual analyses of variance for estimating genetic parameters of the population. The formation of more than one group of divergent genotypes was observed, the geometry characteristics were more impacting for the discrimination of the genotypes, a high phenotypic correlation was observed with the germination variables and dry matter weight. High heritabilities were verified for the variables related to seed quality, indicating success in selecting vigorous genotypes. The Ward-MLM method is a useful tool to detect genetic diversity among genotypes of inbred guava. Thus, the most divergent genotypes with high germination potential can be recommended for future crosses or self-fertilized to obtain new lines in the guava breeding program.

Resumo A goiaba é uma fruta de importância no Brasil e no mundo. No entanto, as pesquisas ainda precisam avançar na área de melhoramento genético e na tecnologia de sementes que é fator fundamental na busca de novos genótipos produtivos e com potencial germinativo, dando apoio a continuidade dos programas de melhoramento. Na busca de metodologia para teste de análise de rotina de sementes de goiaba sob controle genético objetivou-se avaliar o efeito da temperatura e do substrato na germinação de sementes de goiaba oriundas de famílias de irmãos completos. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 5 x 4, constituído pela combinação de cinco temperaturas (25, 30, 35, 20-30 e 25-35 °C) e quatro substratos (rolo de papel, sobre papel, entre areia e sobre areia), com oito repetições de 50 sementes. Foram avaliadas a germinação, o índice de velocidade de germinação e sementes não germinadas vivas. As temperaturas alternadas de 20-30 e 25-35 °C e os substratos rolo de papel, sobre papel e entre areia são as condições adequadas para condução de testes de germinação com sementes de goiaba.

Abstract Guava is an important fruit in Brazil and worldwide. However, research has yet to advance on its breeding and seed technology, an essential factor for the development of productive genotypes with germination potential which would support the continuity of breeding programs. In search of a methodology for routine analysis testing of guava seeds under genetic control, this study examined the effect of temperature and substrate on the germination of guava seeds from full-sib families. The experiment was laid out in a completely randomized design with a 5 × 4 factorial arrangement consisting of the combination of five temperatures (25, 30, 35, 20-30 and 25-35 °C) and four substrates (paper roll, on-paper, in-sand and on-sand), with eight replicates of 50 seeds. Germination, germination speed index and live ungerminated seeds were evaluated. The alternating temperatures of 20-30 and 25-35 °C and the paper roll, on-paper and in-sand substrates are adequate conditions for germination tests with guava seeds.