The chromosome substitution (CS) lines constitute an important genetic and breeding resources, increasing the genetic diversity of Upland cotton from other alien tetraploid species. Two experiments were conducted to quantify low temperature and drought stress effects during early growth stages in 21 cotton CS-lines with parent, Texas Marker (TM)-1. In Experiment I, plants were grown at optimum (30/22°C) and low (22/14°C) temperatures under optimum water and nutrient conditions. In Experiment II, plants were grown at optimum water and drought conditions. Above- and below-ground growth parameters including several root traits were assessed at 25 days after seeding. CS-lines varied significantly varied for many traits measured. Combined low temperature and drought response indices, derived from all measured parameters, showed CS-T04 and CSB08sh showed significantly higher and lower tolerance to low temperature, respectively, while CS-T04 and CS-B22sh showed significantly higher and lower tolerance to drought condition compared to TM-1.

An experiment was conducted to determine temperature effects on switchgrass seed germination, a native species with feedstock potential for the biofuel industry. Stratified seeds were germinated at constant temperatures, 15 to 45°C with 5°C interval. Maximum seed germination (MSG) and germination rate (GR), estimated by fitting sigmoid function to germination-time series data, varied among genotypes. Quadratic and bilinear models best described the MSG and GR responses to temperature, respectively. The mean cardinal temperatures, minimum, optimum and maximum, were 8.1, 26.6 and 45.1ºC for MSG and 11.1, 33.1 and 46.0ºC for GR, respectively, varied among genotypes. Genotypes were classified for temperature tolerance based on cumulative temperature response index: ‘Summer’ and ‘Expresso’ were identified as the most heat- and cold-tolerant genotypes, respectively. The functional algorithms and identified tolerant genotypes may be used to improve switchgrass models for field applications and breeding programs to develop new genotypes with enhanced tolerance for niche environments.

Abiotic stresses cause extensive loss to agriculture production worldwide. Cowpea is an important legume crop grown widely in tropical and subtropical regions where high temperature, ultraviolet-B (UVB) radiation and drought are the common stress factors limiting production. Various vegetative, physiological, biochemical and reproductive plant attributes were assessed under a range of UVB radiation levels in Experiment I and in a combination with two doses of each carbon dioxide concentration [CO2], temperature, and UVB radiation and their interactions in Experiment II by using six cowpea genotypes and sunlit plant growth chambers. The dynamics of photosynthesis and fluorescence processes were assessed in 15 cowpea genotypes under drought condition in Experiment III in pot-grown plants under sunlit conditions. A distinct response pattern was not observed in cowpea in response to UVB radiation form 0 to 15 kJ; however, plants grown under elevated UVB showed reduced photosynthesis resulting in shorter plants and produced smaller flowers and lower seed yield. Increased phenolic compounds appeared to be a defense response to UVB radiation. The growth enhancements observed by doubling of [CO2] were not observed when plants were grown in combination with elevated UVB or temperature which also showed the most detrimental effects on plant growth and seed yield. Results form Experiment I and II revealed that cowpea reproductive traits were highly sensitive to abiotic stresses compared to the vegetative growth and development. A total stress response index (TSRI) technique, derived from all vegetative and reproductive parameters, was used to screen genotypes for their stress tolerance to UVB or combination of stresses. An increase in water use efficiency while maintaining higher rate of photosynthesis was an important drought tolerance mechanism in tolerant cowpea genotypes. Using principal component analysis technique, four groups of the genotypes were identified for their drought tolerance. Evaluating same genotypes across stress conditions revealed that no single genotype has the absolute tolerance characters to all stress conditions. The identified diversity for abiotic stress tolerance among cowpea genotypes and associated traits can be used to develop tolerant genotypes suitable for an agro-ecological niche though traditional breeding or genetic engineering methods.

Drought is the major environmental factor affecting crop growth, yield and quality. Two experiments were conducted to understand rice genotypic variability responses to drought stress conditions during seed germination and early-seedling growth. In Experiment I, the influence of wide range of osmotic stress on seed germination properties of 15 rice cultivars were studied using polyethylene glycol media. In Experiment II, seedling morph-physiological parameters including root traits were quantified by subjecting rice seedlings to three different soil moisture treatments, 100, 66 and 33% field capacity. Rice cultivars differed in their response to drought at both the stages. Cultivars were classified into different drought tolerant groups based cumulative drought response indices. Based on seed- and early-season growth and developmental responses, RU1104122, Rex, CL111 and RU1304154 were identified as drought tolerant among the rice cultivars tested. The identified tolerant cultivars will be a source for rice breeders to develop new drought tolerant cultivars.

The use of common bean (Phaseolus vulgaris L.) cultivars efficient and responsive to phosphorus use is important for increase grain yield and reduce production cost. Thus, the objectives of this work were: (1) evaluate the response of common bean lines in production of dry matter, grain yield components, and accumulation of phosphorus in the plant under different phosphorus availability; (2) investigate the association between these characters; (3) evaluate the genetic variability of common bean lines as the phosphorus availability; (4) identify efficient lines in phosphorus use and responsive to application of mineral by different indexes. For this, four experiments were carried out in a greenhouse of the Plant Science Department at the Santa Maria Federal University during the years 2013 2015, in a completely randomized design in a sub-sub-divided plot. In the first two experiments the phosphorus concentration tested in the nutrient solution were from 0.5 to 2.3 mmol L-1 as part of the main plot; Perola and IPR88 Uirapurú cultivars were evaluated in the sub-plot, and the growing seasons (fall-winter and spring-summer) in the sub-sub-plot. In the third and four experiments were evaluated the efficiency of phosphorus use and 12 genotypes response the low (0.9 mmol L-1) and high (1.9 mmol L-1) phosphorus concentration in the nutrient solution in two growing seasons. Phosphorus concentration in the nutrient solution from 1.33 to 1.84 mmol L-1 provided higher dry mass of pod at pod filling stage (R8), high dry mass of grains at maturation (R9), and higher number of grains and grain yield, for Pérola and IPR88 Uirapurú cultivars. Phosphorus concentration in the nutrient solution from 1.37 to 1.96 mmol L-1 result in high phosphorus concentration in: leaves at first trifoliate leaf (V4), stem at flowering (R6);,leaves, stem and pods at pod filling (R8), grains at maturation (R9), and high grain yield and phytic acid, in growing seasons (fall-winter and spring-summer). The characters dry mass of the leaves, stem and pods at pod filling stage (R8), dry mass of grains at maturity (R9), number of grains and number of pods are promising for allowing indirect selection. The evaluation of the phosphorus concentration in plant tissues at pod filling stage (R8) is promising and allowing indirect selection for the grain yield in common bean. The L 2225, L 2632, L 2527 and L 2411 lines, stood out due to high production of dry mass of stem in low phosphorus concentration in the culture medium. There is genetic variability among common bean lines studied for dry matter production, grain yield and phosphorus accumulation in tissues. The L 2527 line proved to be efficient and responsive for phosphorus use. / O uso de cultivares de feijão (Phaseolus vulgaris L.) eficientes e responsivas a utilização de fósforo é importante para a elevação da produtividade de grãos e para a redução do custo de produção. Diante disso, os objetivos desse trabalho forma: (1) avaliar a resposta de linhagens de feijão submetidas a diferentes disponibilidades de fósforo na produção de massa seca, nos componentes da produtividade de grãos e no acúmulo de fósforo na planta; (2) investigar a associação entre esses caracteres; (3) avaliar a variabilidade genética de linhagens de feijão quanto à disponibilidade de fósforo; (4) identificar linhagens eficientes no uso de fósforo e responsivas a aplicação deste mineral por diferentes índices. Para isso, os experimentos foram desenvolvidos em casa-de-vegetação do Departamento de Fitotecnia da Universidade Federal de Santa Maria (UFSM), durante os anos de 2013 a 2015, em delineamento inteiramente casualizado e parcela sub-sub-dividida. Nos dois primeiros experimentos foram testadas concentrações de fósforo na solução nutritiva de 0,5 a 2,3 mmol L-1 como componentes da parcela principal; as cultivares Pérola e IPR88 Uirapurú na sub-parcela e, os cultivos de outono-inverno e primavera-verão na sub-sub-parcela. No terceiro experimento foram avaliadas a eficiência no uso de fósforo e a resposta de 12 genótipos de feijão em baixa (0,9 mmol L-1) e em alta (1,9 mmol L-1) concentração de fósforo na solução nutritiva, em duas épocas de cultivo. Concentrações de fósforo na solução nutritiva entre 1,33 e 1,84 mmol L-1 proporcionam maior massa seca das vagens no enchimento das vagens (R8), dos grãos na maturação (R9), número de grãos e produtividade de grãos, para os genótipos Pérola e IPR88 Uirapurú, nos cultivo de outono- inverno e primavera-verão. Concentrações de fósforo na solução nutritiva entre 1,37 e 1,96 mmol L-1 acarretam maior concentração de fósforo: nas folhas em terceira folha trifoliada (V4), no caule em floração (R6), nas folhas, caule e vagens em enchimento de vagens (R8) e nos grãos na maturação (R9); produtividade de grãos e concentração de ácido fítico dos grãos, nos cultivos de outono-inverno e primavera-verão. Os caracteres de massa seca das folhas, caule e vagens no enchimento de vagens (R8), massa seca dos grãos na maturação (R9), número de grãos e número de vagens são promissores por permitir seleção indireta. Assim como, a avaliação da concentração de fósforo nos tecidos vegetais no estádio enchimento de vagens (R8) é promissora e permite seleção indireta para a produtividade de grãos. As linhagens L 2225, L 2632, L 2527 e L 2411, destacaram-se por apresentar alta produção de massa seca de caule em baixa concentração de fósforo no meio de cultivo. Existe variabilidade genética entre as linhagens de feijão estudadas, para produção de massa seca, produtividade e acúmulo de fósforo nos tecidos. A linhagem L 2527 mostrou-se eficiente e responsiva ao uso de fósforo para a parte aérea.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The common bean (Phaseolus vulgaris L.) is an important calcium source for human diet, thus the evaluation of the calcium use efficiency in common bean a relevant tool for crop sustainability. The aims of this study were to evaluate the response in common bean cultivars with different calcium concentrations in nutrient solution on dry matter production, yield components and calcium, potassium and magnesium accumulations; to investigate the association between these characters; to evaluate the genetic variability of lines for calcium availability in the solution; and identify lines of common bean-efficient and responsive to calcium application by different indexes. For this, three experiments were conducted from March 2011 to July 2012 in greenhouse, in a completely randomized design, in splitplots. In the first two experiments were tested calcium concentrations in nutrient solution from 1.10 to 4.95 mmol L-1 as components of the main plot and the BRS Expedito, Carioca and Iraí cultivars on subplots in the first experiment, with the exclusion of the cultivar Iraí in the second experiment. The third experiment evaluated the efficiency and the response of the calcium use of 12 different common bean lines at low (1.10 mmol L-1) and high (3.85 mmol L-1) calcium concentrations in the nutrient solution. Higher values for dry matter and grain yield components were observed for 3.30 mmol L-1 and 4.95 mmol L-1 calcium concentrations in the solution. The common bean cultivars acumulate greater quantity of calcium in the leaves, followed by stems, pods and grains. Highest accumulation of calcium in the leaves was obtained at a 4.95 mmol L-1 calcium concentration in the nutrient solution, and the calcium concentration in the leaves was 21 times higher than the value obtained in the bean grains. The increase of calcium concentration in the nutrient solution up to the concentration of 4.95 mmol L-1 does not change the absorption and the accumulation of potassium and magnesium in leaves and grains. Indirect selection by greater dry matter and higher values of the variables that form the grain yield in common bean will be efficient to increase the accumulation of calcium in grains. The lines L 15, L 234, L 246 and L 77 respond to the increase on calcium supply in the solution, because more calcium accumulates in grain in the cultivation with high calcium concentration. The lines L 246 and L 15 are calcium use efficient in the plant, in the acquisition and grain production, and are not responsive to calcium application. The line L 77 is calcium use efficient in the plant and in the grain production and is responsive to the calcium application in the nutrient solution. / O feijão (Phaseolus vulgaris L.) é uma importante fonte de cálcio para a alimentação humana, sendo a avaliação da eficiência no uso de cálcio em feijão uma ferramenta relevante para a sustentabilidade da cultura. Foram objetivos desse trabalho avaliar a resposta de cultivares de feijão a diferentes concentrações de cálcio em solução nutritiva na produção de massa seca, nos componentes da produtividade de grãos e no acúmulo de cálcio, potássio e magnésio; investigar a associação entre esses caracteres; avaliar a variabilidade genética de linhagens de feijão quanto a disponibilidade de cálcio na solução e identificar linhagens eficientes no uso de cálcio e responsivas a aplicação deste mineral por diferentes índices. Para isso foram realizados três experimentos no período de março de 2011 a julho de 2012, em casa-devegetação, em delineamento inteiramente casualizado, com parcelas subdivididas. Nos dois primeiros experimentos foram testadas concentrações de cálcio na solução nutritiva de 1,10 a 4,95 mmol L-1 como componentes da parcela principal e as cultivares BRS Expedito, Carioca e Iraí nas subparcelas no primeiro experimento, com a exclusão da cultivar Iraí para o segundo experimento. No terceiro experimento foram avaliadas a eficiência no uso e a resposta de 12 linhagens de feijão em baixa (1,10 mmol L-1) e em alta (3,85 mmol L-1) concentração de cálcio na solução nutritiva. Maiores valores para massa seca e para os componentes da produtividade de grãos foram observados para as concentrações de 3,30 mmol L-1 e de 4,95 mmol L-1. As cultivares de feijão acumulam maior quantidade de cálcio nas folhas, seguido pelos caules, vagens e grãos. Maior acúmulo de cálcio nas folhas foi obtido na concentração de 4,95 mmol L-1 de cálcio na solução nutritiva, quando a concentração de cálcio nas folhas é 21 vezes superior ao valor obtido nos grãos de feijão. O aumento da concentração de cálcio na solução nutritiva até a concentração de 4,95 mmol L-1 não altera a absorção e o acúmulo de potássio e de magnésio nas folhas e nos grãos de feijão. A seleção indireta pela maior massa seca de parte aérea e maiores valores das variáveis que formam a produtividade de grãos em feijão será eficiente para aumentar o acúmulo de cálcio nos grãos de feijão. As linhagens L 15, L 234, L 246 e L 77 respondem ao aumento do suprimento de cálcio na solução, pois acumulam mais cálcio nos grãos em cultivo com alta concentração deste mineral. As linhagens L 246 e L 15 são eficientes no uso de cálcio na planta, na aquisição de cálcio e na produção de grãos, e não são responsivas à aplicação de cálcio. A linhagem L 77 é eficiente no uso de cálcio na planta e na produção de grãos e é responsiva à aplicação de cálcio na solução nutritiva.