Fall 1977

Municipal Golf Course Can be Profitable (page 3) An Overview of Nitrogen With Emphasis on Its Effects on Turfgrasses (7) The Ideal Par 3 Hole (11) UMass Turfgrass Research Fund (20

Spring 1987 Conference Issue

Phosphorus and Its Effect on Plant Growth (page 3) Dollar Spot Fungicide Control Trial--1977 (9) Forty-Seventh Annual Turf Conference and Second Industrial Show Program (10) Parks for the Year 2000 (15

A time of flight method to measure the speed of sound using a stereo sound card

We present an inexpensive apparatus for measuring the speed of sound, with a time of flight method, using a computer with a stereo sound board. Students measure the speed of sound by timing the delay between the arrivals of a pulse to two microphones placed at different distances from the source. It can serve as a very effective demonstration, providing a quick measurement of the speed of sound in air; we have used it with great success in Open Days in our Department. It can also be used for a full fledged laboratory determination of the speed of sound in air.Comment: Accepted for publication in The Physics Teache

Winter 1977

Influence of Management and Season on Fate of N Applied to Golf Greens (page 3) Potassium: The Mystery Element (9) Effect of IBDU and UF Rate, Date and Frequency of Application on Merion Kentucky Bluegrass (14

Nivel de ploidía y composición genómica de accesiones de Musa spp. en la colección del USDA-ARS Tropical Agriculture Research Station

Plant germplasm collections serve as repositories for important genes. However, insufficient and inaccurate characterization of the genetic diversity in a collection can slow or can prevent full utilization of genetic resources. Bananas and plantains (Musa spp., Colla) are some of the most important food crops in the world. Germplasm characterization efforts in Musa have focused mostly on agronomic and morphological traits although with the advent of molecular markers genotypic characterization efforts are increasing. Genomic composition in Musa is based on a plant's ploidy level and on whether it is of a hybrid origin. Genomic compositions of Musa spp. have been associated with disease and insect resistance, production and flavor characteristics. The Musa spp. collection of the USDA-ARS Tropical Agriculture Research Station consists of 135 accessions, many of which are of unknown genomic composition. In an effort to better characterize the collection, RAPD and PCR-RFLP markers, as well as flow cytometry, were employed to determine genomic composition and ploidy level. Plant accessions maintained in the collection belong to several Musa species and their hybrids with different ploidy levels. In addition, several differences in ploidy as well as genomic composition were identified when comparing findings in this study to those reported in the literature.Los bancos de germoplasma sirven como fuente de genes importantes. Sin embargo, la falta de caracterización o caracterización inexacta de la diversidad dentro de una colección reduce y puede prevenir el uso máximo de los recursos genéticos. Los guineos y plátanos (Musa spp., Colla.) son algunos de los cultivos más importantes como fuente alimenticia en el mundo. La mayoría de los esfuerzos para la caracterización en el género Musa se han enfocado especialmente en rasgos agronómicos y fenotípicos, pero con el desarrollo de técnicas moleculares la caracterización genotípica está progresando. La composición genómica en Musa se basa en el nivel de ploidía como también en si es de origen híbrido. Las diferentes composiciones genómicas se asocian con ciertas características como son la resistencia a insectos y patógenos, la producción y el sabor. La colección de Musa spp. de la Estación de Investigación de Agricultura Tropical del USDA-ARS consiste de 135 accesiones, de las cuales solo a un porcentaje bajo se les conoce la composición genómica exacta. En un esfuerzo por caracterizar mejor la colección se utilizaron las técnicas de RAPDs y PCR-RFLPs al igual que citometría de flujo para determinar la composición genómica. Las plantas de la colección pertenecen a varias especies de Musa y a sus híbridos, y tienen ploidía variada. Además, se encontraron diferencias en ploidía así como en composición genómica cuando se compararon los resultados de este estudio con aquellos resultados reportados en la literatura