Competition of sicklepod, cassia obtusifolia l., densities on soybean, glycine max (l.) merr., at variable row distance

Competition studies with soybeans, Glycine max (L.) Merr. "Bragg." and sicklepod, Cassia obtusifolia L., were conducted at the Agricultural Research and Education Center of the University of Florida in Quincy, Florida. Two field experiments were established, one on May 22, 1975. and the other four weeks later, on June 19, 1975, to determine the competitive effects of various sicklepod densities and the influences of soybean row distances on weed dry matter, soybear plant characteristics, yield components and seed yield, and on soil nutrient content. Control, low, medium, and high sicklepod densities in the first experiment were O, 25,000, 53,000, and 77,000 p1ants/ha, respectively; while the second experiment presented control, low, medium, and high sicklepod densities of O, 36,000, 68,000, and 122,000 plants/ha, respectively. Three soybean row distance treatments were tested using a constant pattern of 90-, 60-, and 45-cm widths throughout the growing season. Three other treatments, evaluated in a variable patern, were initially seeded in 30-cm row widths. Five weeks after planting, an appropriate number of soybean rows were harvested from the 30"cm pattern to establish row distances of 90, 60, and 30-60 cm for the remainder of the season. ln the greenhouse a test was conducted to evaluate the effects af those variables on seed germination and seedling vigor for the next soybean generation. As a result of full-season sicklepod competition, soybean plants were less branched, set fewer leaves, and presented thinner stems as compared to the control. However, height of soybean plants was not affected by the presence of sicklepod. ln one of the two experiments, number of nodes decreased for soybeans under weed campetition. The yield components--number of pods; number of seeds, and seed yield per soybean plant--were all similarly reduced due to weed competition. Seeds per pod were decreased to a lesser extent. Soybean seed yields per unit area were significantly diminished by increasing levels af sicklepod ínfestation. While the control produced 3120 kg/ha, the sicklepod densities of 25,000, 53,000, and 77,000 plants/ha reduced seed yíelds 47, 65, and 73%, respectively. As soybean row distances decreased, number of branches, number of leaves, and stem diameter of soybeans decreased. However, the height of soybean plants increased with narrwing of row width. The components of seed yield--number of pods, number of seeds, and seed yield per soybean plant--diminished as row spacing was reduced. Maximum difference between row distances for these attributes was attained for soybean plants under weed-free conditions. Generally, as row width decreased, soybean seed yield per unit area increased. Specifically, soybear.s in 90-cm rows, either in constant or variable row pattern, yielded less than soybeans in 60- and 30-60-cm rows in the variable pattern. Soil contents of phosphorus, potassium, calcium, and magnesium were not affected by the various levels of sicklepod and soybean populalions. Neither the sicklepod densities nor the soybean row distances influenced seed germination and seedling vigor in the next soybean generation. Sicklepod was a strong competitor with soybeans at all density ranges investigated. Because sicklepod grows taller than soybeans during the reproductive stages of the crop, limited success can be reached by varying row spacing alone. However, this practice is considered an integral measure to complement other methods of sicklepod control. Compared to constant rows, the soybean cropping system using variable row spacings presents the choice of planting soybeans at close row spacings to provide early competition with weeds and the possibility of obtaining a forage crop after the first month of growth, without any decreases on the final seed yields.

Structural Transformation and Productivity in Latin America

We investigate the role of sectorial differences in labor productivity and the process of structural transformation (reallocation of labor across sectors) in accounting for the time path of aggregate productivity across six Latin American countries (Brazil, Chile, Argentina, Colombia, Mexico and Venezuela) from 1950 to 2003. We used a general equilibrium model with three sectors (agriculture, industry and services) calibrated to those six economies. The model is used to compare the trajectory of productivity in each sector of activity with that of the United States and it impact on aggregate productivity.While in Brazil and Argentina, the Service Sector was responsible for reversing the process of catch up in productivity that occurred until the 1980s, in others, like Colombia, Mexico and Venezuela, low productivity growth of the three sectors explain their poor performance.

Avaliação da eficiência de co-transformação de soja (Glycine max (L.) Merrill) via bombardeamento de partículas utilizando um gene de seleção e um gene de interesse em plamídeos diferentes

Visando aumentar a resistência a moléstias fúngicas, o presente trabalho teve como objetivo introduzir um gene (chit1) que codifica uma quitinase do fungo Metarhizium anisopliae em cultivares de soja [Glycine max (L.) Merrill]. A co-transformação foi a estratégia escolhida, visando a obtenção de plantas livres de transgenes marcadores na progênie das plantas transformadas. A co-transformação foi realizada via biolística, tendo como tecido-alvo conjuntos de embriões somáticos globulares das cultivares MG/BR46 Conquista e IAS-5. O plasmídeo pGusHyg, que contém o gene repórter gusA e o gene marcador hpt, foi bombardeado concomitantemente com o plasmídeo pMOG463chit1, que porta o gene chit1. Os conjuntos de embriões bombardeados foram transferidos para meio seletivo contendo higromicina, visando a obtenção de material estavelmente transformado. Os conjuntos embriogênicos higromicina-resistentes foram transferidos seqüencialmente para meios de proliferação D-20 (sem higromicina), maturação e regeneração. No total, foram obtidos 387 e 380 embriões histodiferenciados das cultivares MG/BR46 Conquista e IAS-5, respectivamente. Plantas transgênicas adultas e férteis foram regeneradas. Para avaliar a eficiência da estratégia de cotransformação, foram realizadas análises moleculares de embriões histodiferenciados e de plantas regeneradas. Os resultados obtidos neste trabalho permitiram o cálculo da taxa de co-transformação de 44% para os embriões histodiferenciados da cultivar MG/BR46 Conquista e de 50% para plantas de IAS-5. Não existem, até o momento, relatos de trabalhos em soja utilizando embriões somáticos globulares em proliferação como alvo para estudos de co-transformação.

A proteção dos direitos de propriedade intelectual e as estratégias das empresas de sementes e biotecnologia: uma comparação dos casos americano e brasileiro

O tema central de pesquisa deste estudo é avaliar se a adoção de regras de proteção à novas cultivares de plantas e à modificação genética, impactou as estratégias adotadas pelas empresas nos segmentos de sementes de soja e milho do Brasil, quando comparadas às dos Estados Unidos. Os resultados dessa dupla comparação demonstraram que, no caso do milho híbrido, por contar com uma proteção natural, o estímulo aos investimentos privados ocorreram independentemente da existência de regras formais de apropriação. Essas regras foram essenciais para favorecer tais investimentos na soja, como se nota na transformação da indústria no Brasil após meados da década de 1990. Além disso, embora a modificação genética tenha ocorrido tanto em eventos com características agronômicas, os quais promovem como consequência o aumento de produtividade, quanto para a modificação qualitativa do produto, a demanda do produtor agrícola concentrou-se pelo primeiro tipo, cujo retorno é diretamente apropriado pelo agricultor. Verifica-se ainda, que a complexidade do processo de pesquisa e desenvolvimento e a necessidade de investimentos com altas características locacionais justificam o alto nível de consolidação global dos segmentos de sementes com os de biotecnologia e agroquímicos. Nesses segmentos, a possibilidade de apropriação sobre os direitos da inovação, mostra-se fundamental para motivar os investimentos privados.

Essays on structural transformation, growth and education

This thesis aims to study the impact of structural change on the trajectory of development of emerging economies. More speci cally, we seek to understand how the reallocation of labor from less productive sectors of the economy (e.g., agriculture) to more productive sectors (e.g., industry and services) contributed to the growth of labor productivity in these economies. The thesis is divided into three chapters, besides the introduction. The rst chapter studies the relationship between structural change and economic development in Latin American economies. While the process of reallocation of labor was important to the dynamics of productivity in the period of convergence of these economies, low productivity in some sectors of the economy explained most of the reduction in productivity in the most recent period. In the second chapter, I study the main determinants of growth of the Chinese economy between 1980 and 2005. I show that the increased ow of trade and strong productivity growth in the agricultural sector contributed signi -cantly to China s development in the period. In the third chapter, I study the apparent contradiction between increased levels of schooling and reduction of per capita income in African economies compared to the U.S. economy. The main conclusion is that reducing educational costs explain the retreat of the education di¤erential between African economies and the United States.

Structural transformation and productivity in Latin America

This article examines the e¤ects of sectorial shifts and structural transformation on the recent productivity path of Latin America. We use a four-sector (agriculture, industry, modern services and traditional services) general equilibrium model calibrated to the main economies in the region. The model very closely replicates labor reallocations across sectors and the growth of aggregate labor productivity from 1950 to 2005. Structural transformation explains a sizeable portion of the region s convergence in the rst decades. In most cases, the poor performance of the traditional services sector is the main cause of the slowdown in productivity growth observed in the region after the mid-1970s and is a key factor in explaining the divergence during this period.

Transformation of brain drain of brain gain: incentives to attract talented workforce

The key for the future of any country, firm or group lies in the talent, skills, experience, knowledge and capabilities of its people. Migration of human capital resource on an international level depicts the impact on the developing country having its highly educated individuals migrating to developed countries known as “Brain Drain.” Therefore, evaluation of short-term and long-term talent needs and impacts on any country is critical. This paper aims to complement the existing theoretical brain drain and brain gain literature, focusing on the interaction between investment in education, training, healthcare and government to attract highly talented individuals to a developing a country. The migration study is inclusive of the analysis of the highly talented resources that have committed to or are planning to resettle in their developing native countries after investing in themselves through education. The motivational factors of these highly talented individuals are evaluated to determine key needs and drives attracting these individuals back to China from a developed country (aka. reserve migration).