RESUMOObjetivou-se neste trabalho avaliar o comportamento fisiológico de diferentes genótipos de tomateiro, a fim de contribuir com a seleção de plantas com tolerância ao estresse hídrico. Utilizou-se o delineamento casualizado em blocos, com três blocos e dez tratamentos, sendo: oito genótipos F 2 RC 1 [UFU80-F 2 RC 1 #1 (3.5); UFU102-F 2 RC 1 #7 (13.4); UFU102-F 2 RC 1 #7 (13.3); UFU102-F 2 RC 1 #7 (16.8); UFU102-F 2 RC 1 #3 (2.7); UFU80-F 2 RC 1 #1 (11.8); UFU102-F 2 RC 1 #7 (16.7); UFU102-F 2 RC 1 #3 (14.5) ], e outros dois genótipos utilizados como testemunhas UFU-650 e LA-716. O experimento foi conduzido em ambiente protegido com monitoramento da densidade de fluxo (W m -2 ), radiação solar global (Qg), temperatura do ar (ºC), umidade relativa do ar (%) e o potencial mátrico no substrato (kPa). As características fisiológicas coletadas foram: temperatura foliar (T leaf ), CO 2 interno (Ci), transpiração (E), condutância estomática (gs) e assimilação de CO 2 (A), determinadas pelo analisador portátil de gás no infravermelho -IRGA. Pode-se observar que o acesso selvagem S. pennellii foi 6,96 vezes inferior em relação ao genitor recorrente UFU-650 (linhagem pré-comercial, susceptível ao déficit hídrico). A condutância estomática (gs) apresentou valores significativos entre os genótipos. Os resultados obtidos contribuem para caracterização fisiológica do acesso Solanum pennellii (tolerante a seca) e podem auxiliar na seleção de plantas F 2 RC 1 resistentes ao déficit hídrico. Palavras-chave: déficit hídrico, estresse abiótico, Solanum lycopersicum Selection of tomato genotypes under water stress due to the expression of physiological characteristics ABSTRACTThe objective of this study was to evaluate the physiological behavior of different tomato genotypes to assist in the selection of plants with tolerance to drought stress. It was used three blocks random and ten treatments: eight genotypes F 2 RC 1 [UFU80-F 2 RC 1 #1 (3.5); UFU102-F 2 RC 1 #7 (13.4); UFU102-F 2 RC 1 #7 (13.3); UFU102-F 2 RC 1 #7 (16.8); UFU102-F 2 RC 1 #3 (2.7); UFU80-F 2 RC 1 #1 (11.8); UFU102-F 2 RC 1 #7 (16.7); UFU102-F 2 RC 1 #3 (14.5)], UFU-650 and LA-716. The experiment was conducted in a greenhouse with monitoring the flux density (W m -2 ), solar radiation (Qg), air temperature (°C), relative humidity (%) and the matric potential in the substrate (kPa). The collected physiological characteristics were: leaf temperature (Tleaf), internal CO 2 (Ci), transpiration (E), stomatal conductance (gs) and CO 2 assimilation (A), determined by portable gas analyzer infrared -IRGA. It was observed that the wild tomato S. pennellii was 6.96 times lower than the recurrent parent UFU-650 (pre-commercial line, susceptible to drought). The stomatal conductance (gs) showed significant values among genotypes. The results contribute to physiological characterization access S. pennellii (drought tolerant) and can assist in the selection of F 2 RC 1 plants resistant to drought.
ABSTRACT. The mini tomato production has expanded, becoming an amazing alternative for enterprise. Despite all commercial potential, the cultivation has the occurrence of pests as main obstacle during the crop development. Nowadays, there are no researches that aimed obtaining genotypes with high acylsugar content, capable of providing a broad-spectrum resistance to pests. This study aimed the selection of mini tomato genotypes, with high acylsugar content, and checking the resistance level to the silverleaf whitefly [Bemisia tabaci (Gennadius)] and to the two-spotted spider mites (Tetranychus urticae Koch). Sixteen genotypes were evaluated, from which 12 were on the generation F 2 BC 1 , originated from the interespecific cross between Solanum pennellii versus Solanum lycopersicum L. and 4 were check treatments, being three of cultivated tomatos (cv. Santa Clara, UFU-02, and UFU-73) and the wild accession LA-716 (S. pennellii). The variables analyzed were acylsugar content, repellency to the silverleaf whitefly, repellence to the two-spotted spider mites, and density of glandular trichomes. The genotypes UFU-22-F 2 BC 1 #9 and UFU-73-F 2 BC 1 #11 have high acylsugar content and both are resistant to the pests that were evaluated. New studies must be conducted seeking for inbred lines, obtained from the selected genotypes, aiming to get commercial hybrids with high acylsugar content.
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.
The correct characterization of germplasm banks is fundamental for breeders to succeed in breeding programs. Several studies have sought to obtain genotypes with resistance to pests. However, there is no consensus about which methodology is the most appropriate to characterize a germplasm bank of tomato with different levels of resistance to pests. The objective of this study was to compare methods of multivariate analysis for the evaluation of genetic diversity in tomato genotypes with different levels of resistance to pests. The experiments were conducted at the Vegetable Experimental Station of the Federal University of Uberlândia - Monte Carmelo campus (18º 42’ 43.19” South latitude and 47º 29’ 55.8” West longitude, 873 m altitude), in the period from April 2013 to November 2016. Sixteen genotypes were evaluated from the interspecific cross between LA-716 (S. pennellii) versus pre-commercial line (UFU-057) followed by backcrossing and self-fertilization, along with the pre-commercial line UFU-057 (recurrent parent) Santa Clara and the wild accession S. pennellii (donor genitor). The contents of acylsugar, foliar trichomes, South American tomato pinworm and leaf miner repellency tests were analyzed. The experimental design was the randomized block design totaling 76 plots (19 genotypes x 4 blocks). It was concluded that there was genetic variability among the evaluated genotypes. The method of graphic dispersion by principal components revealed a greater power of discrimination. Genotypes UFU-057F2RC27#4.3, UFU-057F2RC28#2.2 and UFU-057F2RC27#4.7 contain the highest levels of acylsugar, resistance to Liriomyza spp. and T. absoluta.
The objective of this study was to compare methods of multivariate analysis on the evaluation of genetic diversity of mini tomato and to identify promising genotypes with resistance to pests. The experiment was conducted at the Vegetable Experiment Station of the Universidade Federal de Uberlândia, Monte Carmelo campus, from April 2013 to November 2016. The experimental design was a randomized complete block design with 16 treatments and four replications totaling 64 plots, and each plot represented by five plants. Sixteen genotypes were characterized, 12 from the F2RC1 generation, obtained through the interspecific crossing between the wild access LA-716 (Solanum pennellii) and pre-commercial lines of mini tomato (UFU-73 and UFU-2) (Solanum lycopersicum) and the UFU-2 lines. The content of acyl sugar, the amount of glandular trichomes (types I, IV, VI and VII), twospotted spider mite and whitefly resistance were evaluated. We concluded that there exist genetic variability between the genotypes. The number of groups formed by the canonical variated analysis was higher (four groups) than that obtained by the Tocher method (three groups) and UPGMA (three groups), demonstrating a greater discrimination power. The Tocher and UPGMA methods were consistent in the analysis of the genetic divergence in pest resistant germplasm of tomato, with the acyl sugar content being the most important variable. Genotype UFU-73-F2RC1 # 11 is resistant to pest attack, while the other studied lines have intermediate resistance.
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