Variabilidade Genética e Seleção em duas família de cubiu (Solanum sessiliflorum Dunal)
Abstract
Cocona is a plant of the Solanaceae family, native to the Amazon region. However, it is still underexplored and little cultivated in Brazil. Since 1975, the National Institute for Amazonian Research has maintained a Germplasm Bank (BAG-INPA) that once held many accessions. However, after selections carried out since 2000, only nine genotypes are currently conserved. One of them is CUB-04, which has round, yellow fruits with an average weight of 30 g. Within this genotype, two plants were found with fruit sizes and shapes different from those registered in BAG-INPA. Plant 1 had oval, purple fruits with an average weight of 40 g, while Plant 2 had round, purple fruits, also with an average weight of 40 g. Since these characteristics do not exist in any genotype in the bank, it was hypothesized that they resulted from natural crosses or from the mixture of seeds not belonging to the bank. Therefore, the present study aimed to morphoagronomically evaluate two families, P1 and P2, of cocona (Solanum sessiliflorum Dunal) derived from the two plants with atypical fruits within the CUB-04 genotype, in the floodplain of the Solimões River, at the Ariaú/INPA Experimental Station (3°15'16.68""S; 60°14'50.70""W, Iranduba-AM). Four months and 13 days after transplanting to the field, before harvest, the following traits were evaluated: plant height, canopy diameter, stem diameter at the collar, number of flowers and fruits, plant vigor, fruit pubescence, fruit length, and fruit diameter. Descriptive statistics were calculated for P1 (n=203), P2 (n=202), and CUB-04 (n=7). Subsequently, genetic variance and its significance were estimated in both families. Before the first harvest, visual selection based on apparent yield was performed on 45 plants from P1 and 81 plants from P2. In these plants, fruit weight, fruit length and diameter, pulp thickness, number of locules, soluble solids, and pH were evaluated. The results showed that there was significant genetic variability in both families for most morphological traits. Visual selection based on apparent yield achieved an efficiency of approximately 60% for high fruit yield, 90% for greater fruit thickness, and about 98% for greater fruit weight. Therefore, gains from selection for yield, pulp thickness, and fruit size may be obtained in both segregating families.