Rodolfo Bezus

Nitrogen accumulation, partition, and nitrogen-use efficiency in canola under different nitrogen availabilities

Nitrogen (N) accumulation and its partition in a canola (Brassica napus L. ssp. oleifera var. annua) crop growing under different N availabilities were evaluated. Spring canola (cultivar Printol) plants were grown with 0, 30, 60, 90, 120, or 150 kg N ha− 1 applied at sowing. They were harvested at D1 (flower buds covered by leaves), G1 (first flowers fall), and G5 (maturity) phenological stages and separated into stems, leaves, inflorescences, reproductive structures, and seeds according to its development stage. Dry matter and N concentration of each fraction were evaluated. At maturity, seed yield, harvest index and N use efficiencies were evaluated. Nitrogen concentration in the whole plant and its different organs increased with the increase of N applied in the three stages analyzed. The greatest N accumulation (14.44 g m− 2 for 150 kg N ha− 1) was registered at G1 and then it decreased 11% toward maturity. Nitrogen accumulated in seed increased from 2.83 g m− 2 to 7.66 g m− 2 (170% over the control) with application of 150 kg N ha− 1. The highest N harvest index was observed with 30 kg N ha− 1 applying. The apparent N recovery in plant averaged 57% at G1 and it was not modified by N applications. In contrast, N utilization efficiency declined with the N rate increase. The results show that N application at sowing time increases total N accumulated by canola but has little effect on N partition among plant parts even at high rates. Also, it is confirmed the important response of this crop to fertilization but the decrease in its N use efficiency with the increase of N rate. The low average values of apparent N recovery found in this experiment point out the need of adjust fertilizer-applying practices in order to improve N recovery possibilities of the crop.

Development of rice blast under two nitrogen availability conditions

Com o objetivo de avaliar a evolucao da infeccao produzida por Pyricularia oryzae (Cooke) Sacc, em folha e em panicula, foram selecionados tres genotipos de arroz (Oryza sativa). Os genotipos: El Paso 144 (EP), Don Ignacio (DI) e H 316-1-2-1-1 (H 316) foram semeados em condicoes de campo, na Estacao Experimental La Plata, e em duas condicoes de disponibilidade de nitrogenio (testemunha: sem nitrogenio e 150 kg N ha-1 na forma de ureia). O fungo foi inoculado na terceira folha, com uma mistura de racas, e uma concentracao de 1,2 x 105 fragmentos de hifa/ml, incubando-se durante 48 hs em câmara umida. Foram avaliadas a severidade e tipo de mancha na folha e severidade e incidencia na panicula. Foi realizado ANOVA, e as diferencas estatistica foram analizadas pelo teste Tukey (p<0,05). Foram aplicados modelos Log-lineais para dados nao parametricos. Nao foram registradas interacoes genotipo/abudacao nas observacoes em folha, nos estadios de primeiro perefilho (M) e difenciacao (D), a abudacao aumentou a severidade. O coeficiente de correlacao entre o tipo de mancha e porcentagem de severidade em folha foram elevadas. Foi observou interacao entre genotipo/abudacao nos valores de severidade em panicula. Os mesmos diminuiram com a abudacao em EP e DI, mas nao apresentan diferencas em H 316.ABSTRACT Three rice genotypes (Oryza sativa ) were chosen, among somecommercial cultivars and advanced lines, in order to evaluate theinfluence of nitrogen levels on leaf and panicle blast infection causedby Pyricularia grisea (Cooke) Sacc. Three genotypes El Paso 144(EP), Don Ignacio (DI) and H 316-1-2-1-1 (H 316) under two nitrogenlevels (without nitrogen and 150 kg N ha -1 as urea). Plants wereinoculated on third leaf with a mixture of several insolates at aconcentration of 1,2 x 10 5 hyphae fragments /ml and was incubatedduring 48 hours in a wet room. Leaf blast severity and lesion type,and panicle blast severity an incidence were evaluated. Data wereanalyzed by using ANOVA, and differences in means were comparedby Tukey (p<0,05). Log-lineal models were applied with non-parametrical data. Genotype fertilization interaction in relation toleaf blast was not observed, at first shoot (M) and boot stages (D).Nitrogen fertilization increased leaf blast severity. Correlationbetween lesion type and percentage of leaf blast severity was high.Panicle blast severity was significantly reduced by N fertilization ingenotypes EP and but not in H 316.Additional keywords: blast disease, nitrogen,

Mycobiota evolution during storage of paddy, brown and milled rice in different genotypes

The 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 analyzed at 4, 8 and 12 months of storage. Fungi were identified based on their micromorphological characteristics and colonies. The observed genera according to their frequency were: Alternaria, Nigrospora, Epicoccum, Bipolaris, Curvularia, Cladosporium and Fusarium (field fungi) and Penicillium and Aspergillus (storage fungi). The mycobiota composition was different depending on the grain fraction and the period of storage: field fungi were located in the hulls and bran layers, while storage fungi were mainly in the endosperm. The different genotypes showed different susceptibility to contamination.

Evolución el añublo del arroz en dos condiciones de fertilidad nitrogenada

Com o objetivo de avaliar a evolucao da infeccao produzida por Pyricularia oryzae (Cooke) Sacc, em folha e em panicula, foram selecionados tres genotipos de arroz (Oryza sativa). Os genotipos: El Paso 144 (EP), Don Ignacio (DI) e H 316-1-2-1-1 (H 316) foram semeados em condicoes de campo, na Estacao Experimental La Plata, e em duas condicoes de disponibilidade de nitrogenio (testemunha: sem nitrogenio e 150 kg N ha-1 na forma de ureia). O fungo foi inoculado na terceira folha, com uma mistura de racas, e uma concentracao de 1,2 x 105 fragmentos de hifa/ml, incubando-se durante 48 hs em câmara umida. Foram avaliadas a severidade e tipo de mancha na folha e severidade e incidencia na panicula. Foi realizado ANOVA, e as diferencas estatistica foram analizadas pelo teste Tukey (p<0,05). Foram aplicados modelos Log-lineais para dados nao parametricos. Nao foram registradas interacoes genotipo/abudacao nas observacoes em folha, nos estadios de primeiro perefilho (M) e difenciacao (D), a abudacao aumentou a severidade. O coeficiente de correlacao entre o tipo de mancha e porcentagem de severidade em folha foram elevadas. Foi observou interacao entre genotipo/abudacao nos valores de severidade em panicula. Os mesmos diminuiram com a abudacao em EP e DI, mas nao apresentan diferencas em H 316.ABSTRACT Three rice genotypes (Oryza sativa ) were chosen, among somecommercial cultivars and advanced lines, in order to evaluate theinfluence of nitrogen levels on leaf and panicle blast infection causedby Pyricularia grisea (Cooke) Sacc. Three genotypes El Paso 144(EP), Don Ignacio (DI) and H 316-1-2-1-1 (H 316) under two nitrogenlevels (without nitrogen and 150 kg N ha -1 as urea). Plants wereinoculated on third leaf with a mixture of several insolates at aconcentration of 1,2 x 10 5 hyphae fragments /ml and was incubatedduring 48 hours in a wet room. Leaf blast severity and lesion type,and panicle blast severity an incidence were evaluated. Data wereanalyzed by using ANOVA, and differences in means were comparedby Tukey (p<0,05). Log-lineal models were applied with non-parametrical data. Genotype fertilization interaction in relation toleaf blast was not observed, at first shoot (M) and boot stages (D).Nitrogen fertilization increased leaf blast severity. Correlationbetween lesion type and percentage of leaf blast severity was high.Panicle blast severity was significantly reduced by N fertilization ingenotypes EP and but not in H 316.Additional keywords: blast disease, nitrogen,

Evolução do brusone do arroz em duas condições de adubação nitrogenada

Com o objetivo de avaliar a evolucao da infeccao produzida por Pyricularia oryzae (Cooke) Sacc, em folha e em panicula, foram selecionados tres genotipos de arroz (Oryza sativa). Os genotipos: El Paso 144 (EP), Don Ignacio (DI) e H 316-1-2-1-1 (H 316) foram semeados em condicoes de campo, na Estacao Experimental La Plata, e em duas condicoes de disponibilidade de nitrogenio (testemunha: sem nitrogenio e 150 kg N ha-1 na forma de ureia). O fungo foi inoculado na terceira folha, com uma mistura de racas, e uma concentracao de 1,2 x 105 fragmentos de hifa/ml, incubando-se durante 48 hs em câmara umida. Foram avaliadas a severidade e tipo de mancha na folha e severidade e incidencia na panicula. Foi realizado ANOVA, e as diferencas estatistica foram analizadas pelo teste Tukey (p<0,05). Foram aplicados modelos Log-lineais para dados nao parametricos. Nao foram registradas interacoes genotipo/abudacao nas observacoes em folha, nos estadios de primeiro perefilho (M) e difenciacao (D), a abudacao aumentou a severidade. O coeficiente de correlacao entre o tipo de mancha e porcentagem de severidade em folha foram elevadas. Foi observou interacao entre genotipo/abudacao nos valores de severidade em panicula. Os mesmos diminuiram com a abudacao em EP e DI, mas nao apresentan diferencas em H 316.ABSTRACT Three rice genotypes (Oryza sativa ) were chosen, among somecommercial cultivars and advanced lines, in order to evaluate theinfluence of nitrogen levels on leaf and panicle blast infection causedby Pyricularia grisea (Cooke) Sacc. Three genotypes El Paso 144(EP), Don Ignacio (DI) and H 316-1-2-1-1 (H 316) under two nitrogenlevels (without nitrogen and 150 kg N ha -1 as urea). Plants wereinoculated on third leaf with a mixture of several insolates at aconcentration of 1,2 x 10 5 hyphae fragments /ml and was incubatedduring 48 hours in a wet room. Leaf blast severity and lesion type,and panicle blast severity an incidence were evaluated. Data wereanalyzed by using ANOVA, and differences in means were comparedby Tukey (p<0,05). Log-lineal models were applied with non-parametrical data. Genotype fertilization interaction in relation toleaf blast was not observed, at first shoot (M) and boot stages (D).Nitrogen fertilization increased leaf blast severity. Correlationbetween lesion type and percentage of leaf blast severity was high.Panicle blast severity was significantly reduced by N fertilization ingenotypes EP and but not in H 316.Additional keywords: blast disease, nitrogen,