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The aim of the present work was to explore physiological changes provoked by somaclonal variation in response to salinity. Two parental cultivars (La Candelaria and Yerua) and their derived somaclones were used as a source for breeding new rice lines with improved salt tolerance. We studied the effect of NaCl salt stress on chlorophyll fluorescence-related parameters, such as the maximum quantum yield of primary PSII photochemistry (F v /F m ) and the performance index for energy conservation from photon absorbed by PSII antenna (PI ABS ). In addition malondialdehyde (MDA) content and leaf temperature (LT) responses were also measured. In somaclonal lines, F v /F m , PI ABS , MDA and LT showed coefficients of variation of 13.7, 39.3, 25.5, and 3 %, respectively, for La Candelaria and 1.4, 17.6, 34.4 and 3 % for Yerua. However, the fragrant character did not differ in the aromatic somaclonal lines with respect to their parentals. Our results suggest that the F v /F m ratio would not be as good marker of PSII vitality as PI ABS for salinized rice somaclones, unless they are highly susceptible to salinity. On other hand, the MDA content showed a strong negative correlation with the PI ABS content in somaclones of both rice cultivars, suggesting that MDA levels could also be used as an oxidative damage index in rice somaclones.

RESUMOPalavras-chave adicionais: Oryza sativa, sanidade de sementes, patologia de sementes.O grão de arroz é, com frequência, atacado por uma série de patógenos (fungos) durante o armazenamento produzindo danos econômicos e à saúde humana. O objetivo do trabalho foi identificar os gêneros fúngicos presentes em diferentes genótipos de arroz e quantificar sua variação durante o armazenamento. Analisaram-se as frações casca, integral e polido dos genótipos Nutriar (N), H329-5 (H329) e Don Ignácio aos 4, 8 e 12 meses de armazenamento. Os fungos foram identificados por suas características micromorfológicas Pinciroli, M.; Gribaldo, A.; Vidal, A.; Bezus, R.; Sisterna, M. Evolução da micobiota durante o armazenamento do grão de arroz com casca, integral e polido em diferentes genótipos. Summa Phytopathologica, v.39, n.3, p.157-161, 2013. e suas colônias. Os gêneros observados segundo sua frequência foram: Alternaria, Nigrospora, Epicoccum, Bipolaris, Curvularia, Cladosporium e Fusarium (fungos de campo) e Penicillium e Aspergillus (fungos de armazenamento). A composição da micoflora foi diferente segundo fração de grão e tempo de armazenamento: os fungos de campo localizaram-se na casca e no farelo, enquanto os de armazenamento, no endosperma. Os diferentes genótipos apresentaram diferente suscetibilidade à contaminação.Rice (Oryza sativa L.) is one of the major commercial cereal grains in the world, together with wheat and corn. Around 433.8 million tons of milled rice have been produced all over the world (30). Most of the cultivated rice is consumed as head rice, without processing. Therefore, its health is important for both seed use and human consumption. Rice processing involves the milling process. The milled fractions are: paddy rice (without elaboration), brown rice and milled rice.Fungi grown on seeds can cause severe damage (seed abortion, necroses, discoloration, shrunken seeds) and reduce seed yield (17). The mycobiota associated to the grain can be modified by the cultivar (6) and the milling fraction (12) during storage. Neninger et al. (19) reported over 99 species and 59 fungal genera, the most complete list of organisms associated to rice seed. These fungi can be grouped into two categories: "field fungi" which are more or less parasitic and infect the grains before harvest, and "storage fungi" which usually are saprophytes and develop after harvest (3).Alternaria is the most common contaminating fungi detected in cereal grains before harvest. This genus is frequently found on glumes but may cause black spots on the endosperm and may contribute to a decrease in grain quality (20). Alternaria presents several speciesThe rice grain is frequently infected by a series of pathogens (fungi) during its storage, producing damages to the economy and health of humans. The aim of this study was to identify the fungal genera present in different rice genotypes and to quantify their variation during storage. Paddy, brown and milled rice fractions of Nutriar, (N) H329-5(H329) and Don Ignacio genotypes were ana...

Bradyrhizobium is a genus of plant growth-promoting rhizobacteria (PGPR) that have been studied for several decades mainly for the ability to fix diazotrophic nitrogen after having been established endosymbiotically inside root nodules of the legumes of Fabaceae. The aim of this work was to evaluate the capability of Bradyrhizobium to promote the growth of crops belonging to other families, in this case, rice (Oryza sativa), both in laboratory and in field trials. For laboratory test, surface-sterilized rice seeds were soaked with cultures of each strain and planted in pots. Plant length and dry weight were measured after 35 days. For the field test, rice seeds of varieties Yeruá La Plata and Gurí INTA were inoculated with the three best strains observed in the laboratory test and planted in plots. After 60 days of growth, plant length and dry weight were measured. At harvest time, we measured the dry weight of the aerial part, yield and thousand-grain weight. Inoculation with any of the three species described provoked significant increments compared to the uninoculated control at least in one of the parameters measured, both in the laboratory and in the field tests. Bradyrhizobium japonicum E109 was the strain that promoted rice growth the most in the lab while Bradyrhizobium elkanii SEMIA 587 was the strain that promoted rice growth the most in the field, with increments in yield of approximately 1000 kg/ha. Data obtained suggest that the Bradyrhizobium species promoted all rice growth and yield.