RELEASE OF TROPICAL PUMPKIN 'TAÍNA DORADA'

RELEASE OF TROPICAL PUMPKIN 'TAÍNA DORADA

RELEASE OF 'SOLER' TROPICAL PUMPKIN

RELEASE OF 'SOLER' TROPICAL PUMPKI

El cultivar y época de siembra afectan el desempeño de la lechuga en un sistema tropical de producción orgánica

Lettuce is a cool season crop typically grown at high altitudes or during the winter months in tropical climates, but is an important vegetable with potential for increased local production in Puerto Rico. To evaluate year round production potential, eleven lettuce cultivars were grown organically in Lajas under eight environments: winter, spring, summer and fall seasons in 2011 and 2012. All cultivars flowered later in the winter than in other seasons. There was a trend for flowering to be earliest in summer, but in many cultivars bolting occurred equally early in spring or fall. For most cultivars the greatest head weight and harvest yield was observed in the winter or spring season. Fall plantings generally resulted in plants with the smallest heads and lowest yields while summer plantings were intermediate in head weight and yield. ‘Queensland’ was the highest yielder in every season, yielding more than twice the average of all the genotypes in the summer and fall seasons, making it a valuable cultivar for year round production in the tropics. ‘Bergam’s Green’, ‘Jericho’ and ‘Parris Island’ also performed fairly well throughout the year. ‘Black Seeded Simpson’, a locally popular cultivar, performed poorly.  La lechuga es un cultivo de época fresca que típicamente se cultiva en altitud elevada o durante los meses de invierno en climas tropicales, pero es una hortaliza con gran potencial de desarrollo en la producción local en Puerto Rico. Para evaluar el potencial de producción a través del año, se sembraron once cultivares bajo manejo orgánico en Lajas bajo ocho ambientes: las épocas de invierno, primavera, verano y otoño en 2011 y 2012. Todos los cultivares florecieron más tarde en el invierno que en otras épocas. Hubo una tendencia para una florecida más temprana en el verano, pero muchos cultivares florecieron igualmente temprano en primavera u otoño. El mayor peso de cabeza y rendimiento se observó en el invierno o primavera para la mayoría de los cultivares. Las siembras de otoño típicamente resultaron en plantas con las cabezas más pequeñas y los rendimientos más bajos, mientras las siembras de verano fueron intermedias para peso de cabeza y rendimiento. ‘Queensland’ fue el cultivar de mayor rendimiento en todas las épocas, y su rendimiento fue más de dos veces el promedio de todos los genotipos en las épocas de verano y otoño, por lo tanto, es un cultivar valioso para producción todo el año en el trópico. ‘Bergam’s Green’, ‘Jericho’ y ‘Parris Island’ también tuvieron buen rendimiento a través del año. ‘Black Seeded Simpson’, un cultivar comúnmente sembrado en Puerto Rico, tuvo un pobre desempeño. &nbsp

Análisis de sendero de componentes de rendimiento en la calabaza

Path coefficient analysis was carried out in tropical pumpkin (Cucurbita moschata Duchesne) for yield per plant as a function of number of fruit per plant and weight per fruit, using phenotypic and genetic correlations from two diallels: one using five varieties (variety diallel) and a second using five S1 lines derived from the varieties (line diallel). A randomized complete block design with five replications was used to evaluate 15 genotypes from each diallel, not including reciprocals. Direct effects were 300 to 500% greater than indirect effects in the line diallel. In contrast, direct effects were only 17 to 68% greater than indirect effects in the variety diallel. Effects (direct and indirect) were greater (17 to 500%) when genetic correlations rather than phenotype correlations (42 to 440%) were used in the path analysis. Fruit weight showed a greater effect on yield than did number of fruit, with values between 3.2 to 4.9 times the residual effects. Fruit weight and number of fruit can be used as selection criteria to increase yield in tropical pumpkin.  El presente estudio tuvo como objetivo realizar un análisis de sendero para producción por planta en función del número de frutas por planta y el peso por fruta en dos dialélicos de calabaza (Cucurbita moschata Duchesne): uno entre cinco variedades y otro entre cinco lineas S1, originadas de las anteriores. Se utilizaron correlaciones fenotípicas tanto como correlaciones genéticas. Se utilizó un diseño en bloques completos al azar con cinco repeticiones para evaluar los 15 genotipos de cada dialelo (no se incluyeron los recíprocos). Los efectos directos resultaron mayores que los efectos indirectos en el dialélico de líneas (300% a 500%) que en el de variedades (17% a 68%). Los efectos (directos e indirectos) fueron superiores cuando se usaron las correlaciones genéticas (17% a 500%), que cuando se usaron las correlaciones fenotípicas (42% a 440%) en el análisis de sendero. El peso por fruta mostró mayor efecto directo sobre la producción que el número de frutas, con valores entre 3.2 a 4.9 veces el efecto residual. Tanto el peso por fruto como el número de frutas pueden usarse como criterios de selección para incrementar la producción en C. moschata

Efecto de la época y tipo de sombra sobre bacterias endófitas en cafetos (Coffea arabica) en Puerto Rico.

Worldwide, coffee (Coffea arabica) is an economically important crop. In the mountainous zone of Puerto Rico this crop is planted alone or as an intercrop forming an economically and ecologically important agroecosystem. Xylella fastidiosa Wells et al., an endophytic bacteria, causes coffee leaf scorch, which is a serious threat to the crop. Most endophytic bacteria colonize an ecological niche similar to that of phytopathological organisms, thus, some strains of these bacteria could potentially be biological control agents. This study aimed to isolate and characterize endophytic colonizing bacteria in coffee trees under shade and sun, during the rainy and dry seasons. During two years, on coffee farms of Adjuntas, Jayuya, Las Marias and Yauco, we evaluated the effect of season, location, shade and year on the amount and diversity of endophytic bacteria associated with coffee. To contrast endophytic bacterial populations, we analyzed colonyforming units (CFU/mL) and the number of phenotypically different strains (strain diversity) isolated from leaf veins and branches of coffee trees. Higher bacterial populations were observed on branches versus leaf veins (P menor que 0.0001); therefore, in order to obtain a higher number of bacterial diversity, isolations should be performed from branches instead of leaf veins. The interaction of shade type with season was the most common statistically significant interaction, indicative that the effect of the season depends on the type of shade used. During the dry season, statistical differences in the shade and location were found (P menor que 0.05) for leaf veins and branches. In the rainy season, statistical differences were found in the number of strains per tree in shade from leaf veins and tree samples. In general, a high number of bacteria in a location, season or type of shade management was associated with a high degree of strain diversity. Certain endophytic strains might interact in an antagonist manner to Xylella fastidiosa, representing an alternative for controlling the disease.El café, Coffea arábica, es un cultivo de i mportancia económica mundial. En la zona montañosa de Puerto Rico se siembra solo o formando un agroecosistema importante desde el punto de vista económico y ecológico. Xylella fastidiosa Wells et al., una bacteria endófita limitada al xilema y que produce el encorchamiento de la hoja del cafeto, representa una seria amenaza para este cultivo. La gran mayoría de las bacterias endófitas colonizan un nicho ecológico similar al de los organismos fitopatógenos; por lo tanto, algunas cepas son potenciales agentes de control biológico. El presente estudio buscó aislar y caracterizar las bacterias de colonización endofítica en hojas y ramas de cafetos bajo sombra y a sol, durante la época seca y la época lluviosa. Durante dos años, en fincas de café de los pueblos de Adjuntas, Jayuya, Las Marías y Yauco, se determinó el efecto de época, localidad, tipo de sombra y año sobre la cantidad y diversidad de bacterias endófitas asociadas al café. Para contrastar las poblaciones de bacterias endófitas, se analizaron las poblaciones y la diversidad de cepas bacterianas, esto es, unidades formadoras de colonias (UFC/mL), y el número de cepas fenotípicamente distintas (diversidad de cepas) aisladas de hojas y ramas de los cafetos. Se obtuvieron poblaciones bacterianas más altas en las ramas versus las nervaduras de hojas (P menor que 0.0001), por lo que, para obtener mayor representatividad de la diversidad bacteriana, los aislamientos deben realizarse de las ramas y no de las hojas. La interacción tipo de sombra por época fue la que mostró significación estadística en mayor número de veces, indicativo de que el efecto de época dependerá del tipo de sombra utilizado. Durante la época seca se detectaron diferencias estadísticas (P menor que 0.05) en el factor tipo de sombra y localidad en los aislamientos realizados a partir de muestras de ramas y hojas. En la época lluviosa se detectaron diferencias para diversidad de bacterias por árbol para el factor tipo de sombra en muestras de hoja y rama. En general, un número alto de bacterias en una localidad, época o tipo de sombra fue asociado con un alto nivel de diversidad de cepas. Existe la posibilidad de que ciertas cepas endófitas interactúen de forma antagonista con X. fastidiosa, siendo esto una alternativa con potencial para el manejo de la enfermedad

Distribución espacial de cafetos (Coffea arabica L.) posiblemente enfermos con el encorchamiento de la hoja causado por Xylella fastidiosa en Puerto Rico

Coffee (Coffea arabica L.) is an economically and socially important crop. In Puerto Rico, the harvest of 2012 was the lowest in the history of the island, mainly because of the economic crisis and phytosanitary problems. The main production problems are of biotic origin. Coffee Leaf Scorch (CLS) also known as 'crespera' caused by the bacterium Xylella fastidiosa (Xf), results in significant economic losses in many countries. In the Caribbean Basin, Xf causes disease in coffee trees in Costa Rica, and in South America it causes epidemics in Brazil. To determine the presence of Xf in Puerto Rico, coffee trees showing CLS disease symptoms were tested with a double antibody sandwich enzyme linked immune absorbent assay (DAS-ELISA) specific for Xf. Spatial cluster analysis using SAT Scan was carried out on data from potentially symptomatic trees. Few trees (< 5%) had absorbance levels within the range of positive values (a 0.7) for Xf. There were significant differences (p<0.0001, x2) in the percentage of trees suspected of infection with Xf in the dry versus the rainy season. Also, the percentage of suspected trees was variable among localities (p<0.05, x2). Spatial clustering showed more than 14 times greater relative risk of encountering infected coffee trees with Xf at higher altitudes such as in Adjuntas, Jayuya and Yauco (p<0.001), which was related to higher numbers of potential vectors at those localities.El café (Coffea arabica L.) es un cultivo de importancia económica y social. En Puerto Rico en el año 2012 la producción de café tuvo su nivel más bajo en toda la historia de la isla, tanto por los problemas de crisis económica como por los problemas fitosanitarios. Entre las principales enfermedades que afectan al cultivo está el encorchamiento de la hoja ('coffee leaf scorch', CLS) o crespera, causada por la bacteria Xylella fastidiosa (Xf) que ocasiona pérdidas económicas importantes en varios países. En la Cuenca del Caribe, Xf se encuentra en cafetos de Costa Rica, mientras que en Brasil la bacteria causa serias epidemias. Para determinar la distribución espacial de los cafetos posiblemente infectados con Xf, se muestrearon cafetos con síntomas similares a los de CLS. Para detectar a la bacteria en los árboles muestreados se realizó una prueba serológica comercial (DAS-ELISA) específica para Xf. Con datos de los árboles potencialmente infectados se realizaron conglomerados espaciales usando el programa SatScan. Muy pocos (< 5%) de los cafetos dieron lecturas de absorbancia dentro de los valores aceptados como positivos para Xf (a 0.7). Hubo una diferencia (p<0.0001, x2) en la época seca versus la lluviosa en la proporción de cafetos seropositivos según la prueba para Xf. Además, el porcentaje de cafetos seropostivos a Xf varió dependiendo de la localidad muestreada (p<0.05 X2). Los conglomerados espaciales permitieron asociar con mayor riesgo relativo de enfermedad (sospechosos de CLS) a las localidades de mayor altitud: Adjuntas, Jayuya y Yauco (riesgo relativo mayor a 14; P<0.001), lo que estuvo relacionado con conteos altos de vectores potenciales en estas localidades

Inheritance and Genetic Correlations of Certain Traits in Modified Endosperm Texture Opaque-2 Maize (Zea Mays L.)

69 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.Modified endosperm texture may be useful in improving agronomic characteristics in opaque-2 (o2) maize (Zea mays L.). Five methods of quantifying endosperm modification were compared. Visual estimates of endosperm modification were found to be reliable and efficient means of rating modification. Using these estimates cytoplasmic effects on endosperm modification were studied in crosses of four o2 and six modified o2 lines, and xenia effects, genetic variance components, and genetic correlations were determined in a modified population Synthetic Disease Oil o2o2. Variance components were estimated from analyses of S(,1) and S(,2)/S(,1) families and S(,1) progeny means. Plant height, 100 kernel weight, kernel volume, kernel density, percent oil, percent lysine, percent protein, and lysine per 100 grams protein were determined in addition to endosperm modification.Few cytoplasmic differences were found in the 24 reciprocal crosses of o2 by modified o2 lines. Only B37o2 cytoplasm appeared to have an effect on modification levels. Xenia was observed to be of a magnitude that would necessitate controlled pollinations in a breeding program. Endosperm modification, 100 kernal weight, volume, and density were found to be influenced by xenia when the same families in open and self pollinated blocks were compared.Significant genetic variability was observed for all traits in modified Synthetic Disease Oil o2o2. Family mean basis heritabilities were high for all traits except density. Additive genetic variance was important for percent lysine, percent protein, percent oil, L/P, and plant height. Dominance variance was important for endosperm modification, volume, 100 kernel weight, and density. Dominance variance will bias predicted response to selection for the traits in which it is an important component of variance. Modification was negatively correlated with percent lysine and L/P in S(,1) families but not in S(,2) families. Modification was positively correlated with density but not correlated with 100 kernel weight and volume. Increased modification by recurrent S(,1) family selection should be possible in modified Synthetic Disease Oil o2o2. It should be possible to maintain present lysine levels while improving modification by applying some selection pressure.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

GENETIC VARIABILITY AND CORRELATIONS OF YIELDS COMPONENTS AND RESISTANCE TO PHYTOPTHORA INFESTANS, ALTERNARIA SOLANI, AND MELOIDOGYNE SPP. IN TOMATO

Experiments were conducted to determine genetic variability, heritabilities, and genetic correlations of yield components, resistance to Phytopthora infestans, Alternaria solani, and Meloidogyne in eight F2 and five F3 tomato (Lycopersicon esculentum) populations. Three methods were utilized to calculate heritability: (1) Parent-Offspring Regression, (2) Variation among F3 Families, and (3) Components of variance. In the F2 and evaluation for late bliqht (P. infestans) indicated that all eight populations were susceptible to this disease. In the F3 populations were moderately resistant to susceptible to the rootknot nematode (Meloidogyne) but there was no statistical differences among families. The populations were also quite susceptible to A. solari. The amount of genetic variation for yield components varied depending on the population and trait. Although heritabilities varied according to method of calculation, in general, total and commercial yields had low heritabilities across all populations. Number of fruits was often associated with intermediate heritabilities and weight per fruit with intermediate to high heritabilities. The two variance component methods gave similar results while the parent-offspring regression technique resulted in low and non-significant heritabilities. Commercial yield was significantly and positively correlated with most of its components and negatively correlated with nodule number, per cent defoliation, and rate of defoliation. In view of the low heritabilities Single Seed Descent is suggested as a useful breeding technique for selection of the traits discussed

Comportamiento de nuevos genotipos de calabaza bajo varias prácticas culturales

New tropical pumpkin (Cucurbita moschata Duchesne) genotypes were evaluated for yield, flesh (mesocarp) color, pest resistance and seed production as compared with the standard cultivar Soler in six field trials at three Puerto Rico locations during a two-year period (2003-2005). Genotypes included an open-pollinated population (PRShortvine-1) and four lines (E0305-1, E0305-2, E0305-3 and E0305-4) with a semi-bush growth habit, as well as a new long-vine open-pollinated population (PRLongvineSLR). Various within-row (0.9- and 1.9-m) and between-row (1.9- and 3.8-m) planting distances were tested. Not all genotypes nor planting distances were included in each trial. PRLongvineSLR was partially resistant to the melonworm (Diaphania hyalinata), whereas lines E0305-1 and E0305-2 were very susceptible. These same lines, as well as PRShortvine-1, were also susceptible to downy mildew, Pseudoperonospora cubensis. All genotypes produced similar yields. Within-row planting distance generally had no effect on fruit weight, fruit number and yield. All new genotypes had good flesh thickness (>4 cm) and small fruit cavities. Flesh color of PRShortvine-1 and PRLongvineSLR tended to be more orange than that of Soler. Lines E0305-3 and E0305-4 had poor seed production, whereas seed production in fruits of PRShortvine-1 and PRLongvineSLR was similar to that of Soler. Despite some shortcomings, PRShortvine-1 and PRLongvineSLR are two advanced open-pollinated populations that should be considered for formal release on the basis of their field performance, good fruit quality and ability to produce profitable amounts of seed in a seed production program. Se evaluaron nuevos genotipos de calabaza (Cucurbita moschata Duchesne) para rendimiento, color de la pulpa, resistencia a plagas y producción de semillas. Se comparó su comportamiento con el cultivar estándar Soler en seis ensayos en tres localidades en Puerto Rico, durante un periodo de dos años (2003-2005). El estudio incluyó una población experimental de polinización libre (PR Shortvine-1) y cuatro líneas (E0305-1, E0305-2, E0305-3 y E0305-4) con hábito de crecimiento semi-arbustivo, y una población experimental de polinización libre (PR longvineSLR) de bejucos largos. Se evaluaron dos distancias de siembra dentro del surco (0.9 m y 1.9 m) y dos entre surcos (1.9 m y 3.8 m). No todas las distancias de siembra se incluyeron en cada ensayo. PRIongvineSLR demostró ser excepcionalmente resistente al gusano del melón (Diaphania hyalinata), mientras que las líneas E0305-1 y E0305-2 fueron particularmente susceptibles. Estas mismas líneas, al igual que PRShortvine-1, fueron también susceptibles al añublo lanoso (Pseudoperonospora cubensis). Todos los genotipos produjeron rendimientos similares. La distancia entre plantas en el surco no afectó el peso del fruto, número de fruto ni el rendimiento. Todos los nuevos genotipos mostraron buen grosor de pulpa (>4 cm) y una cavidad pequeña. El color de pulpa de PRShortvine-1 y de PRLongvineSLR tiende a ser más anaranjado que el de Soler. Las líneas E0305-3 y E0305-4 tuvieron pobre producción de semilla, mientras que las de PRShortvine-1 y PRLongvineSLR fueron similares a la de Soler. A pesar de algunos defectos, PRShortvine-1 y PRLongvineSLR son dos poblaciones que se deben considerar para liberación a base de su rendimiento en el campo, buena calidad de fruta y habilidad para producir cantidades económicamente rentables de semilla en un programa de producción de semilla