Caracterização e ranqueamento de cultivares de Lactuca sativa L. (Asteraceae) e Allium cepa L. (Alliaceae) na padronização de bioensaios para fitotoxicidade

Abstract

The species Lactuca sativa L. and Allium cepa L. are among the most used as test organisms in plant bioassays. The knowledge of the cultivars about the physiological and genetic aspects is a fundamental step for the standardization and selection of the best genotypes for bioassays. The objective of this work was to characterize, classify and later validate with CdSO4 the cultivars of Lettuce (Lactuca sativa L.) and Cebola (Allium cepa L.) on germination, initial growth and cytogenetic parameters. For this purpose, seeds of 14 cultivars of Lettuce and 13 of commercially obtained Onion were germinated in Petri dishes (70 mm) with 3 mL of distilled water. Plates were mounted in B.O.D (24 ° C) with photoperiod of 12 hours. The evaluated parameters consisted of: percentage of germination, rate of germination, number of normal seedlings, root and shoot length, fresh and dry biomass, mitotic index, chromosomal abnormalities and DNA content. The data were submitted to analysis of variance, the averages being compared by means of the Scott-Knott test (p <0.05), and to the multi-criteria analysis, using Technique for Order Preference by Similarity (TOPSIS) to obtain a ranking of these Cultivars. According to the statistical analysis of the data, the cultivars of Lactuca sativa L. more suitable to the plant bioassays were Summer Babysitter, Great Lakes and Grand Rapids, while for Allium cepa L. Periform Bay, Gold Valley and White Creole were highlighted. From the ranking obtained by TOPSIS, Summer Babysitter and Periform Bay were the best cultivars for Lettuce and Onion, respectively. Both presented higher frequency of chromosomal abnormalities, being chromosome lost and stickiness the predominant anomalies in L. sativa L. and A. cepa L. respectively in the controls. In the toxicity test with the presence of Cadmium metal, the cultivars of both species were sensitive, since the metal interfered in the root and shoot extension, fresh biomass and mitotic index, and increased the frequency of chromosomal abnormalities except For Creole, since Cadmium stimulated the IM.