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[en] In order to determine whether microsites are limiting seedling recruitment and regeneration of Espeletica uribei (an endemic frailejon, a valuable species subject to conservation in the Parque Nacional Natural Chingaza) ten biotic and abiotic variables were evaluated from E. uribei seedling microsites as well as from sites without seedlings. The variables associated with seedling establishment were distance from the nearest reproductive adult, the quality of exposure to light, and associated herbaceous structure. Reduced distances from the nearest reproductive adult made it difficult for the seeds to reach distant microsites due to the principle wind dispersal type (anemochory). Open gaps and associated herbaceous structure positively affect the germination capacity and establishment of the species. The results suggest that E. uribei recruitment is limited by the availability of microsites that meet these conditions. These are important factors to consider when planning future projects for the conservation and restoration of this species.
[en] We developed a faster micropropagation protocol specifically designed for Eucalyptus grandis. Eucalyptus breeding programs use micropropagation protocols to obtain high quality cloned seedlings, but current protocols are excessively time consuming.The protocol has been developed in Argentina, but it can be applied in anywhere. We used nodal segments as initial explants to obtain micropropagated shoots, which were then simultaneously rooted ex vitro and acclimated in a hydroponic system. Nodal segments were cultured in a MS medium supplemented with 1 mg l-1 6-benzylaminopurine, 30 g l-1 sucrose, 1 g l-1 active charcoal and 8 g l-1 agar and incubated for four weeks at 25 ± 2°C under 16 h day photoperiod. Then, micropropagated shoots were exposed 15 seconds to 5000 ppm indol-butyric acid prior to being transferred to a hydroponic system, allowing simultaneous ex vitro rooting and acclimatization. 73 ± 9% of nodal segments grew to generate 1.73 ± 1.03 shoots per explant (length: 0.76 ± 0.44 cm). After four weeks in hydroponic system, 46 ± 4 % of micropropagated shoots developed roots, which represents an acceptable and intermediate rate of success, compared to the reported in vitro rooting rates. Our protocol allowed to obtain micropropagated seedlings in a total timespan of 8 weeks. Our results show that, by utilizing a hydroponic system, traditional protocols to micropropagate Eucalyptus can be substantially enhanced, allowing for improved production dynamics and potentially resulting in better organized seedling manufacturing facilities.
[en] Restinga formations grow on sandy spits of coastal plains, an environment whose conditions limit the growth and development of vegetal species. Studies on restinga gradients are good examples of how plants acclimate to restrictive environments. This work compares three woody species co-occurring in four vegetations of a restinga from Southern Brazil. It pinpoints morpho-anatomical attributes that favor the survival of species faced with spatial variability of soil and light conditions. Results indicate that they respond differently to environmental variables on different scales. The plastic response of morphological attributes is more marked than that of anatomical ones. Varronia curassavica and Dodonaea viscosa showed more xeromorphic features on the more stressful restinga formations while Symphyopappus casarettoi varied between xerophyte to mesophyte forms along the gradient. Individual height, fresh and dry leaf masses, leaf area, specific leaf mass and area, leaf density, and water content are particularly noteworthy. These responses are strategies allowing the studied species to survive in restinga environment with highly variable soil nutrient, water availability, and light conditions. The environmental conditions are important features that modulate de plant morphology along the gradient.
[en] The establishment of invader species in a region generally modifies the ecosystems where they are introduced. In this study we analyze the effect produced by a gleditsia triacanthos (Honey locust) invasion on a Pampean Stream. This organism modifies the temperature and the light reaching the stream. Thermal range shows significant differences between reaches but mean tem between 85 and 95 % down the trees. These modifications reduce the primary gross production of 2.7 to 1.7 g 02. M"2 at spring and of 25 to 20 g 02. M"2 at summer. Respiration in spring and summer is halved at invaded reaches, but net ecosystem metabolism is similar in both reach and seasons. Moreover, the reach invaded by honey locust show scarce macrophytes. We argue that the honey locust reduces the diversity by reduction of macrophytes and their associated organisms but also reduce the primary production causing changes in the food web
[en] A standardized, accurate, and easy system is needed to describe Jerusalem artichoke (Helianthus tuberosus L.) plant development. Therefore, this study was designed to define stages of development descriptions for Jerusalem artichoke. Field experiments were conducted during early rainy season and the post rainy season of 2011 and 2012. Data were collected and uniform growth stage descriptions, based on visually observable events, were developed for the vegetative (V), reproductive (R) and tuberization (T) stages. The V stage was determined by counting the number of developed nodes on the main axis of the Jerusalem artichoke, beginning with emergence of the sprout seedling and ending with the initial visual appearance of the inflorescence. The proposed R stages include R1 (Floral bud formation), R2 (beginning bloom), R3 (flowering), R4 (beginning of anthesis), R5 (seed set) and R6 (seed maturity). The T stage include T1 (stolonization), T2 (tuber initiation), T3 (tuber formation), T4 (tuber bulking), T5 (skin set) and T6 (tuber maturity). The V, R and T stages can be measured separately and concurrently and apply to populations or single plants. The present study revealed that reproductive and tuberization development occurred more rapidly in the post-rainy season than in the early-rainy season. The proposed standard descriptions of Jerusalem artichoke development will help research and extension personnel better communicate results and recommendations related to this crop. (author)
[en] Not only traditional approaches such as serology, antibiotic resistance and plasmid profile analysis but also technologies based on molecular biology have been used for strain identification in studies on microbial ecology. Many methods suffer from certain limitations because they are often laborious and time consuming, requiring analysis of individual nodules, and therefore only a restricted amount of data can be collected. Use of marker genes has become popular, especially when they allow visual identification. The Escherichia coli gusA marker gene has proved to be a highly suitable tool for studying plant-microbe interactions. Nodules containing gusA marked rhizobia can be identified simply by their blue colour, which they produce after incubation in a phosphate buffer containing the substrate X-gluc, but marked bacteria can also be detected on plates or in liquid culture. Colorigenic markers have several advantages, since they are easy to use and it is possible to analyse a large sample size. They are suitable for competition studies of Rhizobium, detecting also double occupancy in nodules, and for studies on motility and survival. Marker genes greatly facilitate screening for successful strains in a specific environment and could be used in future for quality control of inoculants. (author). 30 refs, 3 figs, 1 tab
[en] In the past 20 years, reports on micropropagation and rooting in vitro of avocado shoots, with diverse origins and treatments, have been published. However, none of them reached the level required for large scale propagation of the species. It is considered that, in the first place, the micropropagation of avocado requires an efficient system of rooting. Therefore, a system to induce the rooting in vitro of avocado shoots, based on indole-3-butyric acid (IBA) pulses and some treatments based on thidiazuron (TDZ) was tested, using 40 explants per treatment. The treatments with TDZ did not succeed in rooting shoots. Some treatments with pulses of IBA induced the following rooting results: without growth regulators, 16%; 4,000 mg L-1 of IBA for 5 seconds, 8.3% rooted; 100 mg L-1 for 72 hours, 20%; 50 mg L-1 for 72 hours, 15.4%; 150 mg L-1 for 24 hours, 5% rooted. It is considered possible to improve these results by adjusting the range of IBA concentrations as well as in the time range of pulse applications. Finally, it is easier to establish in vitro explants derived from mature seeds or embryos germinated in vitro. (author)
[en] An efficient protocol for rapid and large scale In vitro propagation of some Pakistani cultivars of date palm has been established using inflorescence explants at Date Palm Research Institute (DPRI), Shah Abdul Latif University (SALU), Khairpur, Pakistan. Immature inflorescences of desired cultivars of date palm detached from mother palms followed by surface sterilization with low torrent of current tap water and then 30 percentage NaOCl/sub 2/ solution, the outer cover were removed in order to get spike explants and cut into the 2-3 cm small pieces and cultured on modified MS medium supplemented with 0.1 mg l-1 2, 4-D + 0.1 mg l-1 IAA + 5.0 mg l-1 NAA for initiation and establishment of cultures. The obtained somatic embryos were subjected to multiplication medium involved 0.1 mg l-1 NAA + 0.05 mg l-1BA. Rooting was achieved using quarter strength MS medium containing 0.1 mg l-1NAA without activated charcoal (AC) initially and then with 3 g l-1 AC. Strong rooted plantlets with 2-3 leaves were transferred to pots contained sand and peat moss mixture (1:1 v/v) with more than 95 percentage success in acclimatization. The acclimatized plants with at least one compound leaf were shifted to the open field conditions at SALU campus for further studying morphological and fruit characterization to ensure the true-to-type nature of tissue culture derived plantlets. High multiplication efficiency and survival percentage with no any somaclonal variation ensured the efficacy of the protocol developed for the production of elite cultivars of date palm of Pakistan and can be used to optimize production of other cultivars of date palm worldwide. (author)
[en] Loquat cv. Mardan is a promising variety in loquat growing areas of northern Punjab and Khyber Pakhtoon Khwa. Loquat growers face serious issue of true to type plants availability. An attempt was made to explore different vegetative propagation techniques to find out most successful method for nursery industry. In the study propagation through cutting (during spring) and grafting during different suitable seasons (spring and monsoon) was examined. Cuttings were treated with different growth regulators to promote rooting. PBZ, IBA and their combinations were applied to the cuttings. Highest success percentage (40%) was achieved with PBZ. This limited success in rooting of cuttings was complete failure in getting plant survival at the end of the study. In the second phase of the experiment different grafting techniques i.e. tongue, cleft and side grafting were evaluated during two different seasons i.e., spring and monsoon. Cleft grafting in the months of March/ April proved to be most successful method in terms of success (70%), days taken for shoot growth, no. of leaves, shoots length, no. of branches. While in monsoon season side grafting was significantly better with a success of 85%. Overall, monsoon side grafting proved to be more successful than any other method. (author)
[en] Gentiana macrophylla, native to mountainous areas of Central and Southern Asia, is most popular remedy for rheumatism and pains in Traditional Chinese Medicine with an extensive demand in local market. Our study aimed to classify G. macrophylla communities and to find out the impact of topographic and soil factors on their diversity and distribution in Dongling mountain meadow, Beijing, China. Seventy five samples in 15 transects separated by 50m distance in altitude along an elevation gradient (1592-2298m) were established by quadrate method. TWINSAPN and CCA were used for classification and ordination, respectively. Six diversity indices (Species richness, Shannon-Weiner heterogeneity, Simpson’s index, Hill’s index, Pielou evenness and McIntosh evenness) were used to analyze the pattern of species diversity and polynomial regression analysis was used to establish their relationship with environmental variables. TWINSPAN classified G. macrophylla communities into 8 types and CCA indicated that soil pH, soil temperature, soil type, disturbance, total N, total K, Mg and Zn were significantly related to these communities. Elevation was the most significant factor that affecting the diversity and distribution of G. macrophylla communities. Significant effect of environment, topography and disturbance to meadow communities of G. macrophylla highly suggests some important measures such as uprooting restriction, tourism limitation in meadow area, monitoring of functional diversity, fertilization, irrigation, cloning and cultivation to protect and conserve it and its communities to be used in medicine industry. (author)