Correlation between grain nutritional content and pasting properties of pre-gelatinized red rice flour

As with any variety of rice, red rice characteristics are subject to varietal differences, growing conditions, types of processing, and nutritional and rheological properties. This study determined the nutritional characteristics (centesimal composition and minerals) and paste viscosity properties of raw grains of four red rice genotypes (Tradicional MNAPB0405, MNACE0501 and MNACH0501) and the paste viscosity properties of pre-gelatinized flours obtained at different cooking times (20, 30 and 40 min). The main nutritional properties were correlated with the pasting properties of the pre-gelatinized flours. The samples showed differences in nutritional properties and paste viscosity. MNAPB0405 and MNACE0501 showed higher levels of fiber and fat and provided higher caloric energy than Tradicional and MNACH0501, which, in turn, showed higher levels of amylose. MNACH0501 showed higher peak viscosity (2402 cP), higher breakdown viscosity (696 cP) and a greater tendency to retrogradation (1510 cP), while Tradicional, MNAPB0405 and MNACE0501 had pasting profiles with peak viscosities varying between 855 and 1093 cP, breaking viscosity below 85 cP and retrogradation tendency between 376 and 1206 cP. The factors genotype and cooking time influenced the rheological behavior of pre-gelatinized flours, decreasing their pasting properties. The protein and amylose levels are correlated with the pasting properties and can be used as indicators of these properties in different genotypes of red rice, whether raw or processed into pre-gelatinized flours.

Response of rice cultivars to nitrogen in upland conditions

Against the background of a growing world population, rice (Oryza sativa L.) consumption is expected to grow faster than its production. Therefore, an appropriate question would be: how to increase productivity in the short-term? In this respect, it becomes important the implementation of modern agricultural production systems, such as upland rice with supplemental sprinkler irrigation. Additional information is needed to maximize the available resources, with special attention given to research on the use of nitrogen. This study aimed to evaluate the agronomic performance of commercial rice cultivars with different plant characteristics in upland conditions with supplemental sprinkler irrigation, when subjected to nitrogen in topdress application at the R1 stage (panicle differentiation). The experiment was arranged in a randomized block with split plot design, with 65 treatments, consisting of the combination of 13 cultivars in the plots, and five nitrogen levels in the subplots (0, 40, 80, 120 and 160 kg ha-1), with four replications. Genetic variability was detected among rice cultivars and the agronomic performance in response to the applied nitrogen. The topdressing application of nitrogen increases, in general, the production components and grain yield in rice. Cultivars BRS Primavera, Caiapó and IAC 202 stood out for grain yield, followed by Baldo, Carnaroli, BRS Curinga and IAC 500 with lower yields.

Effect of acetic acid on rice seeds coated with rice husk ash

Flooded rice cultivation promotes anaerobic conditions, favoring the formation of short chain organic acids such as acetic acid, which may be toxic to the crop. The objective of this study was to evaluate the effect of acetic acid on rice seeds coated with rice husk ash. The experiment was arranged in a 2 x 5 x 5 factorial randomized design, with two cultivars (IRGA 424 and BRS Querência), five doses of coating material (0, 2, 3,4 e 5 g kg-1 seed) and five concentrations of acetic acid (0, 3, 6, 9 and 12 mM), with 4 replications, totaling 50 treatments. The variables first count of germination, germination, shoot and root length, dry weight of shoots and roots were recorded. The results showed that coating rice seeds with rice husk ash up to 5 g kg-1 seed does not influence the performance of rice seeds of cultivars IRGA 424 and BRS Querência when exposed to concentrations of 12 mM acetic acid. The presence of acetic acid in the substrates used for seed germination reduced the vigor and viability of seeds of cultivars IRGA 424 and BRS Querência, as well as seedling development, affecting mainly the roots of BRS Querência.

Heavy metal toxicity in rice and soybean plants cultivated in contaminated soil

Heavy metals can accumulate in soil and cause phytotoxicity in plants with some specific symptoms. The present study evaluated the specific symptoms on rice and soybeans plants caused by excess of heavy metals in soil. Rice and soybean were grown in pots containing soil with different levels of heavy metals. A completely randomized design was used, with four replications, using two crop species and seven sample soils with different contamination levels. Rice and soybean exhibited different responses to the high concentrations of heavy metals in the soil. Rice plants accumulated higher Cu, Mn, Pb and Zn concentrations and were more sensitive to high concentrations of these elements in the soil, absorbing them more easily compared to the soybean plants. However, high available Zn concentrations in the soil caused phytotoxicity symptoms in rice and soybean, mainly chlorosis and inhibited plant growth. Further, high Zn concentrations in the soil reduced the Fe concentration in the shoots of soybean and rice plants to levels considered deficient.

Soil chemical properties affected by cover crops under no-tillage system

The use of cover crops in no-tillage systems (NTS) can significantly improve the soil's fertility. Thus, a study was performed to evaluate changes in chemical properties of soil caused by cover crops in a no-tillage system. The field experiment consisted of the following crop rotation: cover crops/rice/cover crops/rice. The experimental design was in randomized blocks with three replications. Treatments consisted of four cover crops (Brachiaria brizantha(Hochst. ex A. Rich.) Stapf. cv. Marandu, Brachiaria ruziziensis R. Germ. and C.M. Evrard, Panicum maximum Jacq. cv. Colonião, and Pennisetum glaucum(L.) R. Br. cv. BN-2) and fallow (control treatment). Soil samples were collected at the beginning of the summer crop in Oct 2007, Oct 2008 and Oct 2009 at 0-5 cm soil depth. The use of cover crops provided for a significant increase in the level of nutrients, soil organic matter, cation exchange capacity, and base saturation in the soil. Soil fertility improved from the first to second year with the growing of cover crops. The soil under cover crops P. glaucum, B. ruziziensis, and B. brizantha showed higher fertility than the area under fallow.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 2 - Immature stages research at a rice irrigation system location in South-Eastern Brazil

A relation between a rice irrigation system and mosquito breeding was established in a study undertaken at the Ribeira Valley Experimental Station, from January through December 1992. Flooding favoured Anopheles (Nyssorhynchus) and Culex (Melanoconion) species, while empty paddies condition were propitious to Aedes scapularis and Culex (Culex) species. Compared with a more primitive area of the same region, several species showed high a degree of adaptation to the anthropic environment. Among them, Anopheles albitarsis, a potential malaria vector that breeds in the irrigation system, has shown immature stage production thirteen times higher than at the natural breeding sites. In addition, Ae. scapularis, An. oswaldoi, Cx. bastagarius, and Cx. chidesteri presented high levels of synanthropy.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 3- Survey of adult stages at the rice irrigation system and the emergence of Anopheles albitarsis in South-Eastern, Brazil

A study of adult Culicidae ecology was carried out from January 1992 through January 1993 at the rice irrigation system of the Ribeira Valley Experimental Station. The adaptation of Anopheles albitarsis to the anthropic environment became evident through the adult collections made at its various habitats represented by the irrigation system and the edge of the residual pond, as well as at those made within the local patchy residual woods. Other potential disease vectors were prevalent in the irrigated system too. There were Aedes scapularis, Culex nigripalpus and Cx. ribeirensis that were collected at various habitats. Remarkable differences among their prevalences were obtained such as between the natural forest and anthropic environments. In the former An. albitarsis was practically non-existent, thus suggesting that it might be considered as eusynathropic. As the populations of other species seemed to increase in the anthropic environment, they may be regarded as hemisynanthropes. Observations suggest the hypothesis that the development of irrigated land may be a factor in the emergence of An. albitarsis, and some other species, as well as the possibility of an increase in the transmission of mosquito-borne diseases such as malaria.

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 6 - Breeding in empty conditions of rice fields in South-Eastern Brazil

Studies on culicid breeding in empty rice fields were carried out during the cultivation cycle from May to November 1993. This period corresponded to stages 1 and 2, when empty conditions prevailed. Breeding occurred in stage 1 and the first part of stage 2, corresponding respectively to fallow uncultivated and ploughing situations. No breeding was found to take place during the second part of stage 2 when transient floods and harrowing occurred. The predominant species were Aedes scapularis, Culex nigripalpus and Cx. mollis. The Pilosus Group of Culex (Melanoconion) was found at lower densities. Some epidemiological considerations are presented.

Performance indexes of a dot-enzime-linked immunosorbent assay (dot-ELISA) and an ezyme-linked immunosorbent assay (IgG-ELISA) for field surveys of new world leishmaniasis

Diagnostic performance indexes of sensitivity, specificity, positive predictive value and efficiency were determined for dot-ELISA and IgG-ELISA tests in 340 leishmaniasis sera. Sensitivity of the dot-ELISA was significantly lower than IgG-ELISA's; the two tests had indexes of specificity and positive predictive value of the same magnitude. Seventy-eight sera gave a negative dot-ELISA test result and a positive IgG-ELISA test result. When sera were classified according to different criteria as how to interpret this diversity, the kappa statistic did not corroborate the classification indicating that the two tests display a substantial strength of agreement. The results presented indicate that performance indexes accrued in a survey where variables arc well known may be extrapolated to other population studies if the disease presents itself as highly prevalent (due to a selection bias or not) and may be expected to discriminate a disease status among test positives.

Studies on human anti-rabies immunization in Brazil: I - Evaluation of the 3 + 1 pre-exposure vaccination schedule under field conditions

The currently used pre-exposure anti-rabies immunization schedule in Brazil is the one called 3+1, employing suckling mouse brain vaccine (3 doses on alternate days and the last one on day 30). Although satisfactory results were obtained in well controlled experimental groups using this immunization schedule, in our routine practice, VNA levels lower than 0.5 IU/ml are frequently found. We studied the pre-exposure 3+1 schedule under field conditions in different cities on the State of São Paulo, Brazil, under variable and sometimes adverse circumstances, such as the use of different batches of vaccine with different titers, delivered, stored and administered under local conditions. Fifty out of 256 serum samples (19.5%) showed VNA titers lower than 0.5 IU/ml, but they were not distributed homogeneously among the localities studied. While in some cities the results were completely satisfactory, in others almost 40% did not attain the minimum VNA titer required. The results presented here, considered separately, question our currently used procedures for human pre-exposure anti-rabies immunization. The reasons determining this situation are discussed.

Hantavirus pulmonary syndrome in Anajatuba, Maranhão, Brazil

The authors report a confirmed case of hantavirus pulmonary syndrome in the rural area of the municipality of Anajatuba, state of Maranhão. Two other suspected cases from the same region are also described. The confirmed case involved a previously healthy young woman who died with signs and symptoms of acute respiratory insufficiency 5 days after presenting fever, myalgia and a dry cough. The patient was a student who was helping her parents with work in the fields; it was a habit of the family to store rice inside the house. The suspected cases involved two first-degree relatives working as field hands who died of acute respiratory insufficiency 24 and 48 hours, respectively, after presenting fever, myalgia and a dry cough. Both stored rice and corn inside their home. People living in the region reported massive infestations with rats in the woods and fields.