On the San Miguel campus of the Catholic University of Maule, in the city of Talca (Chile), the conductivity and thermal resistance of a geothermal borehole were analyzed through a thermal response test (TRT) based on initial ignoring time (IIT) for 3 different heat injection tests, resulting in the thermal conductivity of at least 1.6 Wm -1 K -1 and a thermal resistance of 0.25 mKW -1 (most unfavorable values). Taking advantage of the heating process through the TRT, the cooling capacity of the vertical geothermal heat exchanger was analyzed from a theoretical and practical point of view. Temperature profiles were obtained along the borehole at different time intervals through a water pressure and temperature sensor, and in this way, an average temperature curve of the borehole until the equilibrium temperature was obtained. The latter was compared with the theoretical curve of the cooling process. The results indicate that the cooling curves obtained in a practical way are similar to the theoretical curves. Together with this, a value for the thermal conductivity of 2.35 Wm -1 K -1 was obtained.

En el campus San Miguel de la Universidad Católica del Maule en la ciudad de Talca (Chile), se analizaron la conductividad y resistencia térmica de un pozo geotérmico por medio de un test de respuesta térmica (TRT) en función de tiempos de descarte (TD) para 3 pruebas de inyección de calor diferentes, resultando la conductividad térmica de, al menos, 1.6 W m -1 K -1 y una resistencia térmica de 0.25 mKW -1 (valores más desfavorables). Aprovechando el proceso de calentamiento a través del TRT, se analizó la capacidad de enfriamiento del intercambiador de calor geotérmico vertical desde un punto de vista teórico y práctico. Se obtuvieron perfiles de temperatura a lo largo del pozo en diferentes intervalos de tiempo por medio de un sensor de presión de agua y temperatura, y de esta forma, se obtuvo una curva de temperatura promedio del pozo hasta recuperar la temperatura de equilibrio. Esta última se comparó con la curva teórica del proceso de enfriamiento. Los resultados indican que las curvas de enfriamiento obtenidas de forma práctica son similares a las curvas teóricas. Junto con esto, se obtuvo un valor para la conductividad térmica de 2.35 Wm -1 K -1 .

Adapted cold tolerant maize germplasm is vastly cultivated in the semi-arid high Andean ecosystem from southern Peru on altitudes ranging from 2500 to 4000 masl and between 15º - 18º south latitude. An important part of maize production is the intensive utilization of about 20 open-pollinated native landraces for food preparation or preferred grain texture and color. Systematic collection, characterization and evaluation of the tropical highland maize landraces from southern Peru began in the early 2003, as part of a cooperative breeding research between the international KWS SAAT AG seed-breeding company from Einbeck, Germany and the Faculty of Agronomy of National University of Tacna, Peru. The native maize germplasm revealed enormous diversity and genetic variation in landraces, but shared some common phenotypic characters, such as, outstanding tolerance to low temperatures, very late growing period ranging from eight to nine months, and a remarkable resistance to lodging. However, heat tolerant and early tropical lowland maize can be harvested in the Peruvian coastal plains at 90-120 days, depending on the growing season. The establishment and conduction of this breeding project was carried out bearing in mind that geneflow from early-mature improved maize germplasm to the cold tolerant native landraces can be achieved without diminishing biodiversity. The utilization of about 15 cold tolerant native maize land races in this preliminary three years breeding research has generated up to date hybrid populations, mainly consisting of backcrossing, half-sib and full-sib progenies to make selections within and among them to develop inbred lines, hybrids, synthetics and varieties. Evaluation of phenotypic responses of the first hybrid populations under the highland environmental conditions at 3350 masl has showed a high frequency of cold tolerant hybrid lines and genotypes with one-two month reduction of the growing period for dry kernels.

El germoplasma de maíz adaptado a bajas temperaturas es ampliamente cultivado dentro de un ecosistema semiárido altoandino del sur del Perú a altitudes que fluctúan entre 2500 y 4000 m s.n.m. y entre las latitudes 15º a 18º Sur. Un aspecto muy importante de la producción de maíz es la intensiva utilización de cerca de 20 cultivares o variedades nativas para la alimentación o por el color o la calidad de textura del grano. La colección sistemática, caracterización y evaluación de las variedades nativas de maíz altoandino del sur del Perú se inició a principios del 2003 como parte de una investigación colaborativa sobre mejoramiento genético de maíz entre la compañía internacional de mejoramiento y producción de semilla híbrida KWS SAAT AG de Einbeck, Alemania, y la Facultad de Agronomía de la Universidad Nacional Jorge Basadre Grohmann de Tacna, Perú. El germoplasma nativo de maíz mostró una enorme diversidad y variabilidad genéticas; sin embargo, presentó algunas características fenotípicas comunes, tales como una marcada tolerancia a bajas temperaturas, un largo periodo vegetativo que fluctúa entre los ocho a nueve meses y una marcada resistencia al tumbado. Por otra parte, las variedades tolerantes al calor del trópico bajo pueden ser cosechadas en las zonas bajas de la costa sur peruana entre 90 a 120 días, dependiendo de la estación climática. El establecimiento y conducción de este proyecto de mejoramiento fue llevado a cabo bajo la hipótesis de que es factible la transferencia de genes de precocidad y de tolerancia a bajas temperaturas de líneas superiores de maíz y del germoplasma altoandino a poblaciones híbridas sin alterar la diversidad genética de la población nativa. La utilización de cerca de 15 variedades nativas tolerantes al frío en estos tres años preliminares de investigación genética ha permitido generar hasta el presente grupos de progenies o poblaciones híbridas, mayormente consistentes de cruzas recurrentes, familias de medios hermanos y hermanos completos para seleccionar dentro y entre estos grupos líneas endogámicas, líneas híbridas, líneas sintéticas y variedades. La evaluación de las respuestas fenotípicas de las primeras poblaciones híbridas bajo las condiciones climáticas de las zonas altoandinas a 3350 m s.n.m. ha mostrado una alta frecuencia de líneas y genotipos promisorios tolerantes al frío y con una reducción de uno a dos meses en su periodo vegetativo para grano seco.

O aparecimento da murcha de Fusarium do algodoeiro, no Estado de São Paulo, em 1957, estimulou a realização de intensos trabalhos de seleção e estudos genealógicos nos materiais da coleção do Instituto Agronômico. Graças à constituição genética favorável da variedade Auburn 56, de origem norte-americana, variedades resistentes a essa doença e adaptadas às condições estaduais têm sido entregues aos lavradores desde 1963. A partir de 'Auburn 56', por seleção genealógica, foram obtidas, até 1975, as variedades IAC RM3 e IAC RM4 e suas populações melhoradas, IAC 16 e IAC 17, propiciando, até o presente, solução ao problema da murcha de Fusarium na lavoura algodoeira paulista. Os resultados mostraram também que a seleção individual realizada nas condições de ambiente diferente do original constitui meio eficiente de melhorar variedades recém-introduzidas no Estado.

Since 1957, when Fusarium wilt was first recognized on cotton fields of the State of São Paulo, Brazil, the development of wilt-resistant cotton, adapted to field conditions of the State, has been the major goal of the breeding program at the Instituto Agronômico de Campinas. At first a large collection of cotton varieties, known as wilt-resistant, was tested in infected soil. 'Auburn 56' was selected as the most promising material. Selection for adaptation and crosses with local varieties have been made during several years. The improvement of 'Auburn 56' resulted in four varieties, IAC RM3, IAC RM4-SM5, IAC 16 and IAC 17, all of them obtained through selection in field conditions and pedegree breeding. Since 1970 only wilt- resistant varieties have been released by the Instituto Agronômico. 'Auburn 56' proved to be very suitable for adaptation to new conditions. It's resistance endured the pathogen's variation, considering the presence of race 6, and possibly of others not identified, in São Paulo, absent in the USA. The results also showed that selection for adaptation to new environments may be a powerful method of increasing variation and of breeding.

São apresentados os resultados de quatro expedições, realizadas entre 1962 e 19652, nas quais foram levantadas as formas perenes de algodoeiro existentes em regiões da bacia do rio São Francisco, dos estados nordestinos, do litoral paulista e adjacências, de Mato Grosso, sul de Goiás e Triângulo Mineiro. À maneira de S. G. Stephens, as formas em aprêço são discriminadas, conforme seu modo de ocorrência, em seis categorias: A) selvagem ou asselvajadas; B) semi-asselvajadas; C) domésticas; D) de subsistência; E) cultivares primitivos; F) tipos nativos melhorados. Consideradas em função do desenvolvimento econômico-social, essas categorias articulam-se formando um sistema que se adequa ao estudo da evolução do algodoeiro como planta cultivada. Rim-de-boi (G. barbadense r. brasiliense Hutch), Quebradinho (G. barbadense L.) e Mocó, ecótipo de G. hirsutum r. marie-galante Hutch., os três tipos principais de algodoeiros nativos, são encontrados nas formas B, C, D e E. Apenas o Mocó apresenta-se, também, como linhagens melhoradas (F) e tem real expressão na economia nacional. Vários outros tipos perenes de G. hirsutum e de G. barbadense, êstes últimos distintos dos tipos nativos, ocorrem como formas domésticas (C) e semi-asselvajadas (B). A única forma selvagem ou asselvajada (A) descoberta - "caicoense" - não parece relacionar-se, pelo menos diretamente, com nenhum dos tipos anteriores. Várias hipóteses são aventadas, principalmente sobre origem, evolução e migração dos três tipos mais difundidos, ampliando as perspectivas das investigações. É apresentado um mapa mostrando a distribuição geográfica dos vários tipos e as regiões de maior interesse a serem exploradas no prosseguimento das investigações.

Four expeditions, covering regions of Brazil, located between 5.° and 25.° south, latitude, were performed by the authors, during the period from 1962 to 1965. They were supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo and their aims were: (a) to determine the present geographical distribution of perennial forms of cotton plants; (b) to get samples of these forms to keep them in herbaria and in living collections, at the Instituto Agronômico, Campinas, for further studies. The working program was based on the S. G. Stephens, discrimination of perennial forms of cotton plants according to the mode of their occurrence, namely: wild, semi-feral, commensal, subsistence, primitive cultigen and improved native type. Several regions of the following states were explored in the expeditions: (1st) regions of the São Francisco river basin of the states Minas Gerais, Bahia and Pernambuco; (2nd) the northeastern region, comprising Alagoas, Pernambuco, Paraíba, Rio Grande do Norte and Ceará; (3rd) coastal regions of the state of São Paulo; (4th) regions of the state of Mato Grosso, southern part of Goiás and a region of the state of Minas Gerais, known as "Triângulo Mineiro". Three native types were recognized as being the most largely dispersed: (1) the "kidney" cotton (Gossypium barbadense r. brasiliense Hutch.) found in most of the studied regions. Its center of origin seems to be the northern part of the state of Mato Grosso; the "Quebradinho" (G. barbandese L.) which is found from the inner regions of the states Goiás, Minas Gerais and Bahia as far as the coastal mountains of São Paulo. Although it is admitted that this type has spread south from the state Maranhão, in the 19th century, its center of origin is not known yet; (3) the "Moco", an ecotype of G. hirsutum r. marie galante Hutch., is present in all semi-arid regions of northeastern Brazil. Of these three types, the latter is the only really important one as economic crop and presenting improved strains. Many evidences indicate the Seridó valley as its center of origin. The three cotton types were found as semi-feral, commensal, subsistence, and primitive cultigen forms. A wild cotton was traced near Caicó, Rio Grande do Norte, and named "caicoense", but it does not seem that it is related with any of the above referred types. Several perennial types of G. hirsutum, distinct from "Mocó", were collected as commensal and semi-feral forms in several regions of the northeast. Some types of G. barbadense, different from the native ones, were acknowledged in coastal regions of Alagoas, Bahia, Rio de Janeiro and São Paulo, and also near the border of Paraguay. They probably are remnants of ancient introductions. The results of the expeditions are shown on a map, pointing out the geographical distribution of the cotton types located.