Little is known about the commercial potential of mini-tomato hybrids obtained from one dwarf parent. Thus, our objective was to evaluate the agronomic performance of mini-tomato hybrids obtained by crossing a dwarf line (A) with normal lines with indeterminate (I), determinate (D) and semi-determinate (SD) growth habits. The experiment was conducted in a greenhouse at the Estação Experimental de Hortaliças at the Universidade Federal de Uberlândia-UFU in Monte Carmelo, Brazil. The experiment was completely randomized with 17 treatments and four repetitions. The genetic material consisted of 16 experimental mini-tomato hybrids from the tomato germplasm bank at UFU, and a commercial hybrid (Mascot) as a control. The following variables were used to evaluate agronomic performance: fruit weight (g); number of fruits plant ; stem diameter (mm); distance between first bunch and soil (cm); internode length (cm) and total soluble solids (°Brix). The growth habit of the parents influenced the performance of the hybrids. In general, the mini-tomato hybrids from dwarf lines differed from the control with respect to all variables except number of fruits plant -1 , number of fruits bunch -1 and stem diameter. On average, hybrids from dwarf lines showed higher productivity (20%), shorter internodes (11%) and a shorter distance between the first bunch and the ground (30%), relative to the control. Using dwarf lines to obtain mini-tomato hybrids was shown to be viable since the hybrids demonstrated better agronomic performance.

Water stress can affect the yield in tomato crops and, despite this, there are few types of research aiming to select tomato genotypes resistant to the water stress using physiological parameters. This experiment aimed to study the variables that are related to the gas exchanges and the efficiency in water use, in the selection of tomato genotypes tolerant to water stress. It was done in a greenhouse, measuring 7 x 21 m, in a randomized complete block design, with four replications (blocks), being five genotypes in the FBC generation, which were previously obtained from an interspecific cross between Solanum pennellii versus S. lycopersicum and three check treatments, two susceptible [UFU-22 (pre-commercial line) and cultivar Santa Clara] and one resistant (S. pennellii). At the beginning of flowering, the plants were submitted to a water stress condition, through irrigation suspension. After that CO assimilation, internal CO, stomatal conductance, transpiration, leaf temperature, instantaneous water use efficiency, intrinsic efficiency of water use, instantaneous carboxylation efficiency, chlorophyll a and b, and the potential leaf water (Ψf) were observed. Almost all variables that were analyzed, except CO assimilation and instantaneous carboxylation efficiency, demonstrated the superiority of the wild accession, S. pennellii, concerning the susceptible check treatments. The high photosynthetic rate and the low stomatal conductance and transpiration, presented by the UFU22/FBC#2 population, allowed a better water use efficiency. Because of that, these physiological characteristics are promising in the selection of tomato genotypes tolerant to water stress.

ABSTRACT:The tomato crop adapts to different climatic conditions. However, the water stress, which is a relevant factor in the tomato cropping, can affect the productivity. This experiment aimed to estimate the genetic variability, after two backcrosses, and select tomato genotypes that are tolerant to water stress induced by mannitol. The advance of the generations was done on the field and the water stress test was done in laboratory atmosphere, in a completely randomized design with four replications. 17 genotypes, in the generation F 2 BC 2 , which were obtained from an interespecific cross between Solanum pennellii and Solanum lycopersicum L. and three check treatments, one resistant [wild access LA-716 (Solanum pennellii)] and two susceptible (cv. Santa Clara and UFU-650), were evaluated. After subjected to the osmotic potential of -0.3 Mpa, the seeds were evaluated for: germination percentage, standard germination percentage, first counting percentage, germination velocity index, average time of germination and initial and final length of radicle. As expected, the wild access, S. pennellii, was better than the susceptible check treatments. The genotype UFU102/F 2 BC 2 #71115 highlighted, compared to the others F 2 BC 2 genotypes and in relation to the three check treatments, susceptible (cv. Santa Clara and UFU-650) and resistant (S. pennellii). Analyzing the genetic diversity, 8 different groups were obtained, being an indicative of genetic variability between the evaluated genotypes. The variable %G contributed with 33.9% in the diversification of the genotypes, presenting as the most important criterion, to be evaluated in genetic diversity studies, in the tomato crop under water stress, induced by mannitol.

PALAVRAS-CHAVELactuca sativa L. Cultivo orgânico Plantas de cobertura KEYWORDS Lactuca sativa L. Organic cultivation Cover crops RESUMO: O cultivo de alface no sistema orgânico é crescente no Brasil. No entanto, para ser cultivada no sistema orgânico, faz-se necessário utilizar sementes provenientes de sistema orgânico conforme exigências da legislação brasileira. Atualmente, são escassas pesquisas referentes ao desempenho agronômico e à qualidade fisiológica de sementes de alface no sistema orgânico. Diante do exposto, o objetivo deste trabalho foi avaliar a produção e a qualidade fisiológica de sementes de alface no sistema orgânico e mineral. Foram realizados dois experimentos distintos no campo [experimento I, cujos tratamentos foram plantas de cobertura na ausência de cama de frango e experimento II, cujos tratamentos foram plantas de cobertura na presença de cama de frango], utilizando o delineamento em blocos casualizados (DBC) e quatro repetições em ambos os experimentos. Para avaliar o efeito do mineral em ambos os experimentos, foram previamente reservadas quatro parcelas em cada experimento, também casualizadas em DBC, para que posteriormente fosse realizado o transplantio da alface na condição convencional (mineral) sem a presença de plantas de cobertura e cama de frango. Pode-se verificar que a adubação orgânica com cama de frango associada a diferentes adubos verdes como planta de cobertura é uma alternativa viável tanto para a produção de alface quanto para a produção e a qualidade fisiológica de sementes. A substituição da adubação mineral pela orgânica é benéfica ao desenvolvimento da alface e de suas sementes. ABSTRACT: Lettuce cultivation in the organic system is increasing in

BORBA, Monique Ellis Aguilar. Selection of tomato genotypes to stress tolerance by water deficiency.