Management Of Plant Populations Research Articles

Spatiotemporal variation in mating system and genetic diversity of Araucaria angustifolia: Implications for conservation and seed collection

Understanding spatiotemporal variations in genetic diversity and mating system can allow policymakers to better support actions towards conservation and management of plant populations. However, multiyear studies are still scarce for many long-lived tree species. Therefore, we herein analyze how genetic diversity, genetic structure and mating system of Araucaria angustifolia vary within and among populations, generations (adults and seed cohorts) and years. We evaluated two A. angustifolia populations occurring in forest-grassland landscapes, one of them for three years. Differences in Ho and He were observed among generations and populations, with significant fixation indexes for all adult and seed cohorts evaluated. Pairwise FST values showed that genetic divergences were greater between populations, followed by those among years, and, finally, less relevant values among generations. No significant spatial genetic structure was found in either population. Paternity correlation, number of pollen donors, coancestry and proportion of half and full-sibs may vary over the years in A. angustifolia. In practical terms, the present study demonstrates how recommendations for seed collection may change according to the evaluated year, such as the number of seed trees, which ranged from 42 to 48. Furthermore, multiyear analyses allow a more comprehensive understanding of the genetic aspects for a long-lived tree species. Finally, we present and discuss these aspects and their variations in space, time and between reproductive events, including recommendations for seed collection.

GIS-based spatial nitrogen management model for maize: short- and long-term marginal net return maximising nitrogen application rates

Crop growth models including CERES-Maize and CROPGRO-Soybean have been used in the past to evaluate causes of spatial yield variability and to evaluate economic consequences of variable rate prescriptions. In this work, a nitrogen prescription program has been developed that simulates the consequences of different nitrogen prescriptions using the DSSAT crop growth models. The objective of this paper is to describe a site-specific nitrogen prescription and economic optimizer program developed for computing spatially optimum N rates over long periods of weather and plant population for maize (Zea mays L.) using the CERES-Maize model. The application of the model was demonstrated on a field in Germany and another one in the USA to evaluate the concept across different environmental conditions. The user can determine the short- and the long-term optimal spatial nitrogen prescription based on crop price and nitrogen cost. The program simulated short-term optimum N applications that averaged 9% (McGarvey field, USA) and 48% (Riech field, Germany) lower than the uniform rates actually applied in the fields. The program indicated different site-specific N management options for low and high yielding fields under the assumed prices for maize and N. The implementation of a site-specific plant population management was investigated. A site-specific-optimization of plant population showed a higher profitability in the heterogeneous field in Germany. Hard pan depth, hard pan factor, root distribution factor and the percentage of available soil water across the heterogeneous field were useful indicators in predicting the magnitude of site-specific plant population benefits over uniform rates.

Traditional management affects the phenotypic diversity of fruits with economic and cultural importance in the Brazilian Savanna

The management of plant populations may cause phenotypic changes in the characteristics of a plant that is targeted by human selection over time, which can therefore lead to the domestication process. Studies about this approach have shown that managed plant populations have the most interesting features for use by human populations because they have more productive plants and larger fruits. To evaluate this effect, the traditional management of Caryocar coriaceum Wittm (pequi) in the Chapada do Araripe region of Northeast Brazil was studied by using a morphometric and ethnobotanical approach. A morphometric analysis of the fruits was conducted, during which the plants were recorded to the following three different management regimes: cultivation, in situ management (collection) and incipient management (the tolerance and protection of individuals). To test the hypothesis that people perceive natural morphological variations in the fruits, local people perception was assessed through different methods. To assess the possible influence of management regimes on fruit morphology, 40 reproductive individuals cultivated, 40 managed in situ and 36 individuals under incipient management were randomly selected, and 20 fruits of each were collected for the morphometric analyses. The fruits from individuals grown under the cultivation system were significantly different from the individuals who were managed in situ and from those under incipient management. The perception study showed that local people perceive great morphological diversity among the study populations, which was consistent with the findings of the morphometric analyses. Based on these results, it could be said that C. coriaceum is in the early stage of the domestication process.

Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

Summary Estimates of seed bank depletion rates are essential for modelling and management of plant populations. The seed bag burial method is often used to measure seed mortality in the soil. However, the density of seeds within seed bags is higher than densities in natural seed banks, which may elevate levels of pathogens and influence seed mortality. The aim of this study was to quantify the effects of fungi and seed density within buried mesh bags on the mortality of seeds. Striga hermonthica was chosen as the study species because it has been widely studied but different methods for measuring seed mortality in the soil have yielded contradictory estimates. Seed bags were buried in soil and exhumed at regular time intervals to monitor mortality of the seeds in three field experiments during two rainy seasons. The effect of fungal activity on seed mortality was evaluated in a fungi exclusion experiment. Differences in seed‐to‐seed interaction were obtained by using two and four densities within the seed bags in consecutive years. Densities were created by mixing 1000 seeds with 0, 10, 100 or 1000 g of coarse sand. The mortality rate was significantly lower when fungi were excluded, indicating the possible role of pathogenic fungi. Decreasing the density of seeds in bags significantly reduced seed mortality, most probably because of decreased seed‐to‐seed contamination by pathogenic fungi. Synthesis and applications. Models of plant populations in general and annual weeds in particular often use values from the literature for seed bank depletion rates. These depletion rates have often been estimated by the seed bag burial method, yet seed density within seed bags may be unrealistically high. Consequently, estimates of seed mortality rates may be too high because of an overestimation of the effects of soil or seed‐borne pathogens. Species that have been classified from such studies as having short‐lived seed banks may need to be re‐assessed using realistic densities either within seed bags or otherwise. Similarly, models of seed bank dynamics based on such overestimated depletion rates may lead to incorrect conclusions regarding the seed banks and, perhaps, the management of weeds and rare species.

Phosphorus and plant population management in groundnut (Arachis hypogaea) fenugreek (TrigonelZa foenurn graecum) cropping system

A field experiment was conducted on the phosphorus and plant population management in groundnut (Arachis hypogaea L.) fenugreek (Trigonella foenum graecum L.) cropping system during 1994 95 in summer season on medium black soils at Pune, Maharashtra. An application of 75 kg P,O,/ha, with the treatment of P solubilizer to seeds before sowing and sowing the crop at 30 cm x 10 cm spacing with 330,000 plant populationlha significantly increased the a I growth, dry matter, yield attributes and yield of grounnut over rest of the . . treatments. However, a dose of 50 kg P,Odha with P solubilizer and sowing at the distance of 30 cm x 10 cm with 333,000 plant populationlha was found to be economical in groundnut. In the second trial as a catch crop and as a residual effect to test the fertility of soil, the green fenugreek yield (tonneslha) increased significantly due to application of 75 kg P,O,Iha given to previous crop over rest of the treatments.

Nutrient- and plant-population management in summer greengram (Phaseolus radiatus)

A field experiment was carried out during 1989 and 1990 to study the response of summer greengram (Phaseolus rndintus L.) to Rhizobium inoculation, plant population and different levels of phosporus. Rhizobium inoculation delayed 50% flowering, whereas it increased the plant height, number of primary brancheslplant, leaf-area index, net assimilation rate, dry-matter accumulation and ultimately seed yield. Among different row spacings (20,30 and 40 cm), 30 cm exhibited its superiority to 20 and 40 cm. All the growth characters were increased significantly with the increasing levels of phosphorus up to 40 kg P20,1ha. Flowenng was delayed with increasing levels of row spacing and phosphorus.

Principles and Practice of Plant Conservation.

Principles and Practice of Plant Conservation is the first exhaustive and systematic treatment of the issues of plant conservation, other books on the subject having been collections of articles on specialized topics or of a regional nature. This book, growing out of a major sponsorship effort by two of the world's leading conservation organizations to 'assert the fundamental importance of plants in all conservation activities', provides the well-integrated coverage that arises from an expert's thoughtful analysis of the entire subject. Commissioned by the World Wide Fund for Nature and IUCN - The World Conservation Union as part of their joint endeavor of 'building the capacity to conserve', this work by David R. Given elucidates the concepts that underlie successful conservation efforts. Drawing on his own work and involving international collaboration, the author also presents a large number of real-life case studies that illustrate the principles of conservation in action. Chapters are devoted to the natural - and unnatural - causes of plant rarity and endangerment, and the management of plant populations in natural habitats, in modified landscapes, and off-site to preserve germplasm. Going beyond the biology of conservation, other chapters are devoted to the ethical, educational, and economic aspects of plant conservation. Cyrille de Klemm, an expert on international law, has contributed a chapter on conservation legislation. Plants play critical roles in the web of life, providing the food and shelter on which animals depend. As human population and development pressures on the world's biota increase, it is in the best interest of all to use plant resources wisely and sustainably.That will be possible only if plant diversity is maintained, and Principles and Practice of Plant Conservation is an essential reference for those concerned with how best to preserve what we have.

Principles and practice of plant conservation

Principles and Practice of Plant Conservation is the first exhaustive and systematic treatment of the issues of plant conservation, other books on the subject having been collections of articles on specialized topics or of a regional nature. This book, growing out of a major sponsorship effort by two of the world's leading conservation organizations to 'assert the fundamental importance of plants in all conservation activities', provides the well-integrated coverage that arises from an expert's thoughtful analysis of the entire subject. Commissioned by the World Wide Fund for Nature and IUCN - The World Conservation Union as part of their joint endeavor of 'building the capacity to conserve', this work by David R. Given elucidates the concepts that underlie successful conservation efforts. Drawing on his own work and involving international collaboration, the author also presents a large number of real-life case studies that illustrate the principles of conservation in action. Chapters are devoted to the natural - and unnatural - causes of plant rarity and endangerment, and the management of plant populations in natural habitats, in modified landscapes, and off-site to preserve germplasm. Going beyond the biology of conservation, other chapters are devoted to the ethical, educational, and economic aspects of plant conservation. Cyrille de Klemm, an expert on international law, has contributed a chapter on conservation legislation. Plants play critical roles in the web of life, providing the food and shelter on which animals depend. As human population and development pressures on the world's biota increase, it is in the best interest of all to use plant resources wisely and sustainably.That will be possible only if plant diversity is maintained, and Principles and Practice of Plant Conservation is an essential reference for those concerned with how best to preserve what we have.