Recuperação do genitor recorrente após dois retrocruzamentos em tomateiro anão do tipo Santa Cruz

Abstract

Tomato (Solanum lycopersicum L.) has great socioeconomic relevance, being one of the most cultivated worldwide. Possessing great diversity, the tomato in the Brazilian market is classified in the following groups: “Santa Cruz, Minitomato, Salad, Persimmon and Saladete”, among which the “Santa Cruz” group stands out. In breeding programs, the aim has been to obtain more productive hybrids. Increasing tomato productivity entails taking on the challenge of seeking increments from the quantitative inheritance, but this type of gene action for productivity is difficult to introgress., this possibility exists through the use of dwarf parental, which introgresses favorable genes in this sense Hybrids from a dwarf parent have a short internode, resulting in more compact plants. with a greater number of hands per linear meter of stem and consequently greater productivity. This strategy has high potential, but there are still no Santa-type dwarf tomato populations. Cruz, so the breeders use the method of backcrosses.The objective of this breeding method is the introgression of a scope character into elite genotypes. highly adapted, called recurrent parent. However, despite the large number of studies addressing the method of backcrosses in tomato, currently there is little information about the effectiveness of this method in germplasm of dwarf tomato. Therefore, the objective of this work was to evaluate the increment after each backcross in dwarf tomato Santa Cruz type. The experiment was carried out in a greenhouse, from October 2019 to March 2020 in the Experimental Station for Vegetables of the Federal University of Uberlândia (UFU), Monte campus Carmelo-MG (18º42'43.19" S, 47º29'55.8"W and altitude of 873 m). The genetic material evaluated consisted of 6 dwarf tomato populations from the first backcross (BC1), 13 dwarf tomato populations from the second backcross (BC2), donor parent and Santa Clara commercial control, totaling 21 genotypes. The wild access Solanum pennellii present in this research was used only to compare the variable related to resistance to pest arthropods BC1 and BC2. Due to the expression of the dwarf phenotype being of recessive and monogenic origin, backcrosses were performed for recessive allele transfer. Sowing was carried out in polystyrene trays (200 cells) on October 3, 2019. transplanting took place 36 days after sowing into plastic pots with a capacity of 5 liters. So much in the trays and in the vases, commercial substrate based on coconut fiber was used. The plants were tutored with ribbon. Following the experiment, a randomized block design was used with 22 treatments and 4 repetitions. The experimental plots consisted of 6 plants, distributed in double rows at 0.3 x 0.3 m spacing. A spacing of 0.8 m was used between the double lines, totaling 504 plants. The dwarf populations of both generations of backcrosses (BC1 and BC2) were superior to the parent donor for the characters Average weight of fruits (AWF), Pulp thickness (PT), and Fruit diameter (FD).

Keywords: Genetic Improvement, Backcrosses, Solanum lycopersicum.

¹ Major Professor: Gabriel Mascarenhas Maciel – UFU.