RESPOSTA DA AVEIA CULTIVAR SÃO CARLOS À ADUBAÇÃO NPK, EM DOIS TIPOS DE SOLO, NO ESTADO DE SÃO PAULO

Peanut (Arachis hypogaea L.) cultivars resistant to Pythium myriotylum Drechs. and Rhizoctonia solani Kuhn, are needed for effective management of pod rotting diseases. The low efficiency of field screening for disease reaction in breeding for resistance has emphasized the need for improved evaluation methods. Anatomical examinations of roots, stems, leaves, pegs, and shells were made of six genotypes (TxAG-3, PI 341885, Toalson, Starr, Florunner, and Goldin I) with various degrees of resistance to pod rots in search of traits that might be used effectively in screening for disease reaction. The palisade mesophyll cells of 50-day old plants were arranged more compactly in pod rot resistant than in susceptible genotypes. An index representing total width (pm) of palisade cells/mm leaf blade was more discriminative in distinguishing among genotypes than average of either cell width or cell number alone. The distribution of lignin in peanut shells was correlated with pod rot resistance. The cell walls in the epicarp and sclerenchymatous mesocarp were thicker and more lignified in the resistant than in the susceptible genotypes. Genotypic digerences in lignin distribution were readily apparent at lOOx when shell sections were stained with phloroglucinol. Associations between anatomical traits of stems, pegs, roots, or juvenile plant leaflets and field pod rot reaction were not consistent among all genotypes. However, lignindistribution in pods, and an index representing Fm of palisade cells/mm of leaf blade individually or in combination, might be used effectively to supplement field evaluations in screening breeding lines for pod disease reaction.'Contribution from the Texas Agric. Exp. Stn., Texas A&M Univ., College Station, TA No. 20169. Part of a Ph. D. dissertation submitted by the senior author. Partial support provided as a graduate scholarship by EMBRAPA -Empresa Brasileiria de Pesquisa Agropecuaria.

RESUMO -Com a finalidade de determinar as doses de N, P e K para obter a máxima produção econômica de forragem para a linhagem UPF 87111, nos sistemas de plantio convencional e plantio com cobertura morta, foram instalados experimentos em Latossolo VermelhoAmarelo Distrófico típico, em São Carlos, SP. O delineamento experimental foi o fatorial fracionado tipo (1/2)4 3 com dois blocos ao acaso, total de 32 parcelas, sem repetição. Os tratamentos foram quatro doses de N e de K 2 O (0, 70, 140 e 210 kg ha -1 ), como uréia e cloreto de potássio, e quatro doses de P 2 O 5 (0, 60, 120, 180 kg ha -1 ), como superfosfato triplo. As doses de N, P e K para a produção de forragem de aveia com máxima receita líquida foram, em kg ha -1 para o plantio convencional: N =160, P 2 O 5 = 180, K 2 O = 180 e para o plantio com cobertura morta: N = 200, P 2 O 5 = 120, K 2 O = 95, com produções de matéria seca de, respectivamente, 7.398 kg ha -1 e 8.111 kg ha -1 .Palavras-chave: Avena sativa, fósforo, nitrogênio, potássio, produção de forragem Response of Oats to Fertilization on Red Yellow Latosol in Two Planting SystemsABSTRACT -Two field experiments were carried out on a Red Yellow Latosol (Hapludox), at São Carlos, SP in order to determine the rates of N, P, and K to obtain maximum economic return per area of forage yield for the oat line UPF 87111 grown in two planting systems: conventional tillage and mulch-covered. The experimental design was a fractionated factorial type (1/2)4 3 , with two blocks. The treatments consisted of four rates of N and K 2 O (0, 70, 140, and 210 kg ha -1 ), using urea and potassium chloride, and four rates of P 2 O 5 (0, 60, 120 and 180 kg ha -1 ), using triple superphosphate. The N, P, and K rates for maximum profit were, in kg ha -1 for conventional tillage: N = 160, P 2 O 5 = 180, K 2 O = 180; and for mulch-covered: N = 200, P 2 O 5 = 120, K 2 O = 95 resulting in forage yields of, respectively, 7,398 and 8,111 kg ha -1 of dry matter. In both planting systems, the use of nitrogen resulted in higher forage yield per unit of applied fertilizer.

The pigeonpea [Cajanus cajan (L) Millspaugh] is one of the most important perennial legume crops utilized in the food, fodder, soil conservation, crop-livestock integrated systems, reclaiming of degraded pastures and symbiotic nitrogen fixation. Microsatellite markers were used to estimate the genetic diversity of 77 pigeonpea genotypes selected from the germplasm collections at Embrapa Cattle-Southeast and, to evaluate their transferability to Phaseolus vulgaris and Vigna unguiculata species. The number of alleles per locus ranged from 2 to12, with an average of 5.1 alleles. The PIC values ranged from 0.11 to 0.80 (average 0.49) and the D values from 0.23 to 0.91 (average 0.58). The averages of observed and expected heterozygosity were 0.25 and 0.47, respectively, showing a deficit in heterozygosity. A model-based Bayesian approach implemented in the software STRUCTURE was used to assign genotypes into clusters. A dendrogram was constructed based on the modified Roger's genetic distances using a neighbor-joining method (NJ). A total of four clusters were assembled by STRUCTURE and a strong tendency of correspondence between the Bayesian clusters in the NJ tree was observed. The genetic distance ranged from 0.09 to 0.62 (average 0.37), showing a low genetic diversity in the pigeonpea genotypes. Transferability of pigeonpea-specific microsatellites revealed a cross-amplification and the presence of polymorphic alleles in P. vulgaris and V. unguiculata

Microsatellite (SSR) markers were developed for the following tropical forage species, using accessions available from the plant genetic resources (PGR) collections held by EMBRAPA (Brazilian Agricultural Research Corporation): Brachiaria brizantha, B. humidicola, Panicum maximum, Paspalum spp., Stylosanthes capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides and Centrosema spp. The markers were used to analyze population structure and genetic diversity, evolution and origin of the genetic variability in the center of origin, mating systems and genetic resources in EMBRAPA's germplasm bank. The results shed light on the amount of genetic variation within and between populations, revealed the need in some cases for further plant collection to adequately represent the species in PGR collections, allowed us to assemble core collections (subsets of the total collections) that should contain most of the available diversity and (in the case of the legumes) showed the need to avoid unwanted outcrossing when regenerating conserved material. The data will allow plant breeders to better select accessions for hybrid production, discriminate between genotypes and use marker-assisted selection in breeding programs. Our results will also underpin the construction of genetic maps, mapping of genes of agronomic interest and numerous other studies on genetic variability, population structure, gene flow and reproductive systems for the tropical forage species studied in this work. ResumenSe desarrollaron marcadores microsatélite (SSR) para las siguientes especies forrajeras tropicales, usando accesiones de germoplasma disponibles en las colecciones de recursos genéticos mantenidas por EMBRAPA (Empresa Brasileira capitata, S. guianensis, S. macrocephala, Calopogonium mucunoides y Centrosema spp. Los marcadores se usaron para analizar la estructura de las poblaciones y su diversidad genética; la evolución y el origen de la variabilidad gené-tica en los respectivos centros de origen; los sistemas reproductivos; y los recursos genéticos en el banco de germoplasma de EMBRAPA. Los resultados arrojaron luz sobre la magnitud de la variación genética dentro de y entre poblaciones; revelaron la necesidad, para algunas especies, de incrementar las colecciones de germoplasma y así obtener una adecuada representación de las especies en las colecciones de recursos genéticos; permitieron establecer colecciones núcleo (subconjuntos de colecciones grandes), representativas de la diversidad genética disponible en las respectivas colecciones completas; y mostró, para las leguminosas, el riesgo de cruzamientos no deseados al multiplicar semilla de las accesiones conservadas. La información obtenida facilitará a los fitomejoradores la selección de accesiones para la generación de híbridos, la distinción entre genotipos, y el uso de la selección asistida por marcadores en programas de fitomejoramiento. Los resultados también ayudarán para la construcción de mapas genéticos, el mapeo de genes de interés agronómico y otros estudios...