Viviane Kopp da Luz

Dissimilaridade genética em mutantes de aveia tolerantes e sensíveis a ácidos orgânicos

ABSTRACT GENETIC DISSIMILARITY IN OAT ( AVENA SATIVA L.) TOLERANT AND SENSITIVEMUTANTS TO ORGANIC ACIDS In order to cultivate oats ( Avena sativa L.) as an economically alternative in low lands, it is necessaryto use cultivars tolerant to the main organic acids produced by organic matter decomposition resultingfrom no tillage systems. The objectives of this work were estimate genetic dissimilarity among M 3 mutantfamilies and the oat cultivar UFRGS 14 using ISSR markers; and to detect genomic regions associatedwith organic acids toxicity. Thirty M 3 mutant families from the Plant Genomic Center of the College ofAgronomy “Eliseu Maciel”, derived from the cultivar UFRGS 14 irradiated with gamma ray (Co 60 ) at400 Gy dosage were used. The genetic characterization was carried out using the ISSR marker technique.The results indicated that UBC 854, 855 and 811 primers allowed the identification of genomic regionsrelated to organic acid toxicity tolerance, while UBC 850 and 826 primers of genomic regions associatedto organic acid sensitivity.

Evaluation of Rice Genotypes under Propionate Stress

Abstract The objective of the present work was to evaluate the response of 25 rice genotypes to propionate, a compound largely produced in low‐drainage and high‐organic matter‐content soils. The work was performed in hydroponics with four doses and a random block design with three replications. The variables measured were root (RL) and shoot (SL) length, number of roots (NR), and root (RDM) and shoot (SDM) dry matter. Analyses of variance, relative performance, and regression fitting were performed, showing significance for most variables. The variable RL was the most affected by propionate, and the use of this variable for screening genotypes indicated 6 tolerant and 19 sensitive genotypes. Most tolerant genotypes belonged to irrigated japonica.

Caracterização de famílias mutantes de arroz para tolerância ao frio nos períodos vegetativo e reprodutivo

Low temperatures that occur during the cultivation of rice in the Southern region of Brazil cause reductions in to the yield and quality of the rice grain. Genotypes tolerant to low temperatures would be an alternative to minimize these problems. In the present work cold tolerance was evaluated in rice families (M4 generation) in the vegetative and reproductive phases, in order to identify possible genetic variability. For the evaluation in the vegetative stage, 10 seeds from each family were placed in cell trays and kept at 13 oC for 10 days in controlled chamber with 12 hour day light. The evaluation at the reproductive stage consisted of the application of low temperature at anthesis, by a stress of 15 oC for 7 days. The results suggest that in the vegetative phase, 6 families presented 0-20% reduction in stature, showing a high degree of tolerance. For the reproductive phase there were no families showing higher tolerance than the tolerant control.

Avaliação de genótipos de arroz sob efeito do ácido butírico

Hydromorphic soils have low drainage capacity and are used mainly for growing irrigated rice.. This condition favors the development of anaerobic microorganisms that produce phytotoxic substances. The objective of this work was to evaluate the response of 25 rice genotypes to butyric acid, a phytotoxic compound produced in low-drainage soils with high organic matter content. This work was performed by hydroponics with four acid doses as treatments using a random block design with three replications. The variables measured were root (CR) and shoot (CPA) length, number of roots (NR) and root (MSR) and shoot (MSPA) dry matter. Analysis of variance, relative performance and regression fitting were performed. Significance for genotype and dose was found for all variables. Significance for the interaction (genotype vs. dose) was found only for CR and MSR. The variable CR was the most influenced by the acid and the regression established for these variables revealed nine tolerant and 16 sensitive genotypes. Genotypes developed for irrigated systems were more tolerant.

Avaliação de genótipos de aveia branca sob estresse de ácidos orgânicos

The association of anaerobic conditions with high organic matter content in hydromorphic soils favors the development of anaerobic microorganisms that produce phytotoxic substances, especially short chain organic acids. The objective of this investigation was to evaluate the response of 20 oat (Avena sativa L.) genotypes to the exposure of acetic, propionic and butyric acids in hydroponic system. Three doses (0; 3 and 6 mM) of a mixture of the three acids at a 6:3:1 ratio, respectively were tested. The experimental design was randomized blocks with three replications on a factorial scheme. Measured variables were root (CR) shoot (CPA) length, root number (NR), root (MSR) and shoot (MSPA) dry matter. Variance analyses and regression fitness were performed. The effects of the interaction between doses and genotypes were significant for the variables CR and MSR. The regression curves indicated two genotypes (OR-3 e FAPA-5) with stable root growth and three (OR-3, UFRGS-17 e UPF-15) with stable dry matter accumulation under organic acid stresses. The characterization of these genotypes regarding organic acid phytotoxic action is an important resource for breeding programs aiming at to develop high yielding cultivars for no-tillage or minimal tillage systems in hydromorphic soils of southern Brazil.

Análise da germinação de cultivares de arroz submetidas a estresse por ácido acético

The objective of this research was to evaluate the germination of 12 rice genotypes under acetic acid stress, a phytotoxic compound produced in low drainage soils with high organic matter content. The tests were conducted with the first count of germination (PCG) and germination (G) of the genotypes subjected to 0mM, 4mM, 8mM and 12mM acetic acid concentrations. The seed of each genotype was placed in germitest paper that was embedded with treatment solutions and packaged in individual bags. The germination was performed at 25°C and the counts were carried out at 7 (PCG) and 14 days (G). A factorial random block design was performed with four replications of 50 seeds per genotype. The regressions set for the variables showed three genotypes with germination stability under acetic acid stress.

Identification of variability for agronomically important traits in rice mutant families

The increase of yield potential in new rice (Oryza sativa L.) varieties has been a major challenge for genetic improvement. The generation of mutants, followed by their characterization, constitutes a great possibility to isolate and select genes and genotypes that present agronomic traits of interest. This study aimed to evaluate the effect of chemical mutagen ethyl methane sulphonate (EMS) on agronomic traits in 340 M3 families of rice derived from BRS Querencia cultivar. Seeds from each family and the original genotype BRS Querencia were sown in the experimental field, and the characters main panicle length, main panicle weight, main panicle grain weight, flag leaf width and plant height were evaluated. Data were subjected to analysis of variance (p ≤ 0.05), and a comparison of means was carried out by Dunnetts test at 5% significance. The results show that there is genetic variability among the mutant families, suggesting that the mutagen EMS at 1.5% is effective for generating mutants for all assessed traits. Among the characters, plant height was the most affected by the mutagen, which provided an increase in the character. For the main panicle length character, seven families showed means above the control; for main panicle weight and grain weight, four and six mutant families were observed, respectively, with a superior performance in comparison to the control.

Rice Genotype Responses to Acetate to Improve No‐Tillage and Minimal‐Tillage Systems

The goal of this work was to evaluate the response of 25 rice genotypes to the toxic effect of acetate, which is commonly produced in low‐drainage and organic‐matter‐rich soils. The work was performed in hydroponics with four acetate doses. The experimental design was random blocks with three replications on a factorial scheme. The variables root (RL) and shoot (SL) length, number of roots (NR), and root (RDM) and shoot (SDM) dry matter were measured. Analyses of variance, relative performance, and regression adjustments were used. Only the dose × genotype interaction effect for SL, NR, and SDM were not significant. Among the variables analyzed, RL was influenced the most by the acetate treatments. The regressions established for this variable revealed 6 tolerant and 19 sensitive genotypes. Most of the tolerant genotypes were irrigated japonica.

Characterization of herbicide tolerant rice genotypes under hydroponic culture

Authors declare no conflict of interest The use of nutrient solution combined with different herbicide concentrations allows the evaluation and discrimination of tolerant and non-tolerant genotypes to imidazolinone herbicides. The objectives of this research were to identify possible morphological characteristics to be used as markers of resistance to imidazolinones, as well as the identification of herbicide doses and evaluation time to discriminate sensitive and tolerant genotypes of rice under hydroponic systems. Six rice genotypes four characterized as sensitive, BRS Querência, BRS Border, BRS Atalanta and BRS Pampa and two as tolerant, BRS Sinuelo CL and PUITA INTA CL to imidazolinones were tested in a hydroponic system. Four doses of herbicide were tested, which were evaluated at 7, 14, 21 and 28 days after transplantation. The insertion of the first leaf was the most responsive variable and can be used as morphological marker in experiments for selecting rice genotypes tolerant to imidazolinones. The best time to discriminate genotypes is the 7 day of development. The concentration of herbicide that enables better discrimination between tolerant and sensitive genotypes is 25 μg L, according to the methods described in this bioassay.

Response of rice genotypes subjected to salt stress

Authors declare no conflict of interest Soils with high salt concentrations (NaCl) may affect plant development and nutrient uptake in rice. The objective of this experiment was to evaluate the response of rice cultivars released by Embrapa Clima Temperado to salt stress at the germination and seedling stages. Four NaCl concentrations (0, 40, 80 and 120 mM) and a random factorial design 4×6 (dose × genotype), the cultivars belonging to the Embrapa germplasm collection were evaluated, BRS Bojuru (the only tolerant variety), BRS Pampa, BRS 7 Taim, BRS Querência, BRS Atalanta and BRS Sinuelo CL, with three replicates. After 14 days, the levels of Na, K, Ca and Mg absorbed by the plant shoots and roots were determined. NaCl was not significantly present in the germination stage. In the first germination count, BRS Bojuru and BRS 7 Taim decreased the germination with the increase in salt. The length of the first leaf in the 40 mM dose at 14 days of development (vegetative stage) is indicated as morphological marker for discriminating sensitive and tolerant genotypes to salinity in hydroponic system. The cultivar BRS Pampa showed higher ability of leaf Ca and Mg translocation under salt stress conditions.