Seleção de linhagens de berinjela tolerantes a alta temperatura e heterose em seus híbridos

Abstract

Eggplant is an oleraceous from Solanaceae family, which its ideal temperature for development is between 22 and 32ºC. Values above 33ºC cause a drastic decrease in productivity due to the effects of high temperature. Because of this, the aim of this work is to select lineages and F1 hybrids of high-temperature tolerant eggplants. To pursue these goals three experiments were conduct between the years of 2016 and 2017 at the Universidade Federal Rural de Pernambuco, Recife, PE. The first experiment was conduct in a greenhouse between May and September of 2016. It was evaluated ten morphological aspects recommended by the International Board for Plant Genetic Resources (IBPGR) acquired from 24 genotypes arranged in four random blocks. Data were submitted to variance analysis (p<0.01) and cluster analysis by Tocher’s method and UPGMA, having the generalized Mahalanobis distance as a measure of dissimilarity. The second experiment was conducted between December of 2016 and May of 2017. Eight characters were analyzed in 22 genotypes arranged in the randomized block design with four replicates, conducted in a greenhouse and in field. Data were submitted to an analysis of joint variance and the means of genotypes and environment grouped by Scott-Knott test (p<0.01). The genetic, phenotypic and environmental correlations were also estimated. In the last experiment, seven lineages were studied, 12 F1 hybrids were attained from a partial diallel and the Ciça F1 hybrid as witness. The experiment was design in a randomized complete block with four replicates, performed between the months of August and December of 2017. Data were submitted to variance analysis and the mean grouped by the Scott-Knott test (p<0.01). To obtain the estimates of general combining ability (GCA) and specific combining ability (SCA), the means of genitors and F1 hybrids were submitted to diallelic analysis. Estimates of heterosis related to the mean of genitors were attained for each F1 hybrid. According with data acquired in the first experiment the fruit length (FL), fruit width (FW), and fruit length/width ratio (FLWR) explained 90,72% of the total genetic dissimilarity. Multivariate techniques were partially agreeing with each other and allowed visualization of the genetic variability between the 24 genotypes studied for all the characters in lesser or greater extent. The results of the second experiment indicated that the correlations were positive for the pairs: Number of Fruits per Plant (NFP) x Index of fixation of fruits (IFF), NFP x Production per Plant (PP) and PP x IFF. The correlation was negative for the pair NFP x PP. Between the characters pollen viability (PV), IFF, NFP and PP the associations were low or negative on both environment. Greater means for PV, NFP and PP were observed in the growth at the greenhouse, while in the field the genotypes achieved better performance for IFF, Fruit Weight (FWe), FL, FW, FLWR. In high temperature conditions, genotypes CNPH 135, CNPH 93, CNPH 79, CNPH 410, CNPH 84, CNPH 71, CNPH 668, Ajimurasaki F1 and Kokushi Onaga F1 excelled with a good IFF and the CNPH 135 with the best IFF, PP, PV and FWe. In 45.45% of genotypes values for IFF were low, around 21.32% to 40.51%. In the field, genotypes CNPH 84 and CNPH 668 had the best IFF (>60%). Finally, in the third experiment, the results of diallelic analysis showed a prevalence of GCA over SCA in most of characters, except PV. According to the GCA estimates, the genitor CNPH 135 was the one that presented the best results. The effect of SCA was important in the control of most characters, except FL and FW. Such results show the importance of additive and non-additive gene effects and point out a larger participation of additive gene action in controlling most of the characters of interest for a selection of high-temperature tolerant genotypes. The F1 hybrids were superior to the average of genitors, with positive heterosis for characters PV, IFF, NFP and PP; for the rest of characters it was observed positive and negative heterosis in some hybrid combinations, showing the possibility of exploration of heterosis for different shapes and sizes of fruits.