Methane emission from a flooded rice field under pre-germinated system

ABSTRACT: Local greenhouse gas flow measurement studies have been encouraged at a global level as a subsidy for national and state inventories. This study aimed to evaluate the seasonal methane emission during the 2008/2009 harvest, from an irrigated rice plantation, under pre-germinated system, in the municipality of Tremembé, State of São Paulo, using the static chamber technique and gas chromatography. The study showed high seasonal emission of methane (CH4) for the studied area, probably due to the long flooding period. It was estimated the CH4 emission factor (6.2 kg CH4 ha-1 dia-1), the partial global warming potential (pGWP, 26.2 Mg CO2eq growing season-1 ha-1) and the yield-scaled pGWP (YpGWP, 3.9 kg CO2eq kg grain).

VALIDAÇÃO DO ARRANJO ESPACIAL DO PERCEVEJO-DO-COLMO EM ARROZ IRRIGADO POR INUNDAÇÃO

In order to spatial arrangement validation of Tibraca limbativentris Stal, 1860 (Hemiptera: Pentatomidae) in flooded rice field located at the “Planalto da Campanha” Region, Rio Grande do Sul (RS), Brazil, was carried out a study in flooded rice fields at Itaqui, Rio Grande do Sul State, Brazil, in the 2009/10, 2010/11 and 2011/12 harvests. Were established georeferenced grids for the samplings, totaling 81 points spaced ~50 m in the 2009/10 harvest and, 693 and 352 points in the 2010/11 and 2011/12 harvests, respectively, both with equidistant points ~10 m. Adults and nymphs samplings were performed on each point of the regular grids. We conducted a descriptive statistical analysis for the adults, nymphs and adults + nymphs variables by calculations the mean, standard deviation and minimum and maximum values and dispersion indices: variance/mean, Morisita index, k index, Green coefficient and Taylor potency. The rice stem bug spatial arrangement has been validated when the dispersion indices showed similar results. The rice stem bug T. limbativentris spatial arrangement in flooded rice is the aggregate type, regardless of the infestation level and life stage of the insect.

Geostatistics applied to the study of the spatial distribution of Tibraca limbativentris in flooded rice fields

Tibraca limbativentris (rice stem bug) is an insect highly injurious to the rice crop in Brazil. The aim of this research was to define the spatial distribution of the T. limbativentris and improve the sampling process by means of geostatistical application techniques and construction of prediction maps in a flooded rice field located in the "Planalto da Campanha" Region, Rio Grande do Sul (RS), Brazil. The experiments were conducted in rice crop in the municipality of Itaqui - RS, in the crop years of 2009/10, 2010/11 and 2011/12, counting fortnightly the number of nymphs and adults in a georeferenced grid with points spaced at 50m in the first year and in 10m in the another years. It was performed a geostatistical analysis by means adjusting semivariogram and interpolation of numeric data by kriging to verify the spatial dependence and the subsequent mapping population. The results obtained indicated that the rice stem bug, T. limbativentris, has a strong spatial dependence. The prediction maps allow estimating population density of the pest and visualization of the spatial distribution in flooded rice fields, enabling the improvement of the traditional method of sampling for rice stem bug

Flavobacterium oryzae sp. nov., isolated from a flooded rice field, and emended descriptions of Flavobacterium flevense, Flavobacterium yonginense and Flavobacterium myungsuense

A bacterial strain, designated Jyi-05T, was isolated from a flooded rice field and characterized using a polyphasic taxonomic approach. Cells of strain Jyi-05T were Gram-stain-negative, strictly aerobic, bright-yellow-pigmented rods that were motile by gliding. Growth occurred at 10–30 °C (optimum 30 °C), at pH 6.5–7.5 (optimum pH 7.0) and with 0–2 % (w/v) NaCl (optimum 1 %, w/v, NaCl). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Jyi-05T belonged to the genus Flavobacterium and was most closely related to Flavobacterium flevense DSM 1076T with sequence similarity of 97.6 %. Strain Jyi-05T contained iso-C15 : 0 (16.6 %), anteiso-C15 : 0 (10.8 %), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 10.3 %), iso-C17 : 0 3-OH (9.2 %), C16 : 0 (7.3 %) and iso-C15 : 0 3-OH (7.2 %) as the predominant fatty acids. The major isoprenoid quinone was MK-6. The polar lipid profile consisted of phosphatidylethanolamine and several uncharacterized aminophospholipids and phospholipids. The major polyamine was homospermidine. The genomic DNA G+C content of strain Jyi-05T was 34.2 mol%. The DNA–DNA relatedness of strain Jyi-05T with respect to recognized species of the genus Flavobacterium was less than 70 %. On the basis of the phylogenetic inference and phenotypic data, strain Jyi-05T should be classified as a novel species, for which the name Flavobacterium oryzae sp. nov. is proposed. The type strain is Jyi-05T ( = BCRC 80522T = LMG 27292T = KCTC 32240T). Emended descriptions of Flavobacterium flevense , Flavobacterium yonginense and Flavobacterium myungsuense are also presented.