ABSTRACT
Our objectives were to study characteristics of the fruit (weight, percentage of husk/grain), to determine the concentration and accumulation of nutrients in the fruits, grain and husk, and to verify the existence of genetic diversity in Coffea canephora genotypes. The experiment was conducted with 20 genotypes in a four-year-old plantation, in a randomized block design with four replications and five plants per plot. The fruits were oven-dried, depulped (husk separated from the grain) and sent to a laboratory for nutritional analysis. Macronutrients N and K were the most accumulated/exported in fruits, respectively. In addition, the different genotype control cycles influenced the accumulation of nutrients in the fruits. There was genetic diversity among the 20 C. canephora genotypes, studied for the characteristics of concentration and percentage of grain/straw nutrients in the fruit. Genotypes 2, 8 and 13 were the ones with the greatest genetic distance, consequently they are the most dissimilar when compared to the other genotypes. Genotypes 8 and 1 stand out for having a higher proportion of fruit weight in relation to grains. Therefore, they are the genotypes that need a smaller amount of fruit to produce 1000 kg of ground coffee.
ABSTRACT
O presente trabalho visou empregar um estudo metanalítico para sumarizar e analisar dados sobre adubação nitrogenada em pastagens formadas por gramíneas dos gêneros Brachiaria, Cynodon e Panicum. Foram selecionados 36 trabalhos de pesquisa realizados no Brasil nos últimos 10 anos, incluindo artigos científicos, teses e dissertações. Com base nos dados contidos nesses trabalhos, foi calculado o incremento relativo de matéria seca e de proteína bruta em relação ao tratamento controle (ausência de adubação nitrogenada) e a eficiência da utilização do nitrogênio na produção de matéria seca e proteína bruta. Os dados obtidos foram submetidos à análise de variância para efeito linear e quadrático em cada uma das variáveis dentro de cada gênero e, no caso de significância, foi realizada análise de regressão. A produção de matéria seca e de proteína bruta de forrageiras tropicais responde de forma expressiva à adubação nitrogenada, principalmente a segunda, porém o acréscimo nas doses de nitrogênio reduz a eficiência da adubação. Verificou-se uma frequente omissão de informações relevantes em trabalhos com adubação nitrogenada em pastagens.(AU)
The study aimed to employ a meta-analytic study to summarize and analyze data on nitrogen fertilization in grasslands formed by grasses of the genera Brachiaria, Cynodon and Panicum. A sample of 36 research projects carried out in Brazil in the last ten years, including scientific papers, theses and dissertations were selected. From the data contained in these works, relative dry matter and crude protein increment compared to the control treatment (absence of nitrogen fertilization) and the efficiency of nitrogen use in the production of dry matter and crude protein were calculated. Data were subjected to analysis of variance for linear and quadratic effect on each variable within each genus and, in case of significance, regression analysis was performed. The production of dry matter and crude protein of tropical forages responds greatly to nitrogen fertilization, especially the second, but the increase in nitrogen rates reduces the efficiency of fertilization. There was a frequent omission of relevant information in scientific works on nitrogen fertilization in grasslands.(AU)
Subject(s)
Composting/methods , Poaceae/chemistry , Poaceae/metabolism , Meta-Analysis , Nitrogen Compounds/administration & dosageABSTRACT
Explaining the evolution and maintenance of polyandry remains a key challenge in evolutionary ecology. One appealing explanation is the sexually selected sperm (SSS) hypothesis, which proposes that polyandry evolves due to indirect selection stemming from positive genetic covariance with male fertilization efficiency, and hence with a male's success in postcopulatory competition for paternity. However, the SSS hypothesis relies on verbal analogy with "sexy-son" models explaining coevolution of female preferences for male displays, and explicit models that validate the basic SSS principle are surprisingly lacking. We developed analogous genetically explicit individual-based models describing the SSS and "sexy-son" processes. We show that the analogy between the two is only partly valid, such that the genetic correlation arising between polyandry and fertilization efficiency is generally smaller than that arising between preference and display, resulting in less reliable coevolution. Importantly, indirect selection was too weak to cause polyandry to evolve in the presence of negative direct selection. Negatively biased mutations on fertilization efficiency did not generally rescue runaway evolution of polyandry unless realized fertilization was highly skewed toward a single male, and coevolution was even weaker given random mating order effects on fertilization. Our models suggest that the SSS process is, on its own, unlikely to generally explain the evolution of polyandry.
