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DocumentAerenchyma formation in roots and entry point of oxygen in stems of Syzygium kunstleri grown in hypoxic conditions
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.Aerenchyma serves as a low-resistance O2 transport pathway which makes the plant to survive in flooding conditions. When Syzygium kunstleri, tropical swamp woody plant species, is exposed to hypoxic conditions, primary and secondary aerenchyma(PA, SA) develop in stems and roots. The aim of this study is to investigate the development of PA and SA in the adventitious root, and investigate the entry point of O2 in stem of S. kunstleri sapling grown in hypoxic condition. We prepared cross sections of 0.5cm intervals from adventitious root(>10cm) developed in 0.1% agar medium to observe the longitudinal distribution of PA and SA under light and fluorescence microscopes. The entry point of O2 was investigated by measuring the change of oxygen partial pressure(pO2) by Clark-type O2 microelectrode at the adventitious root while changing the position of stem exposed to N2 or air. N2 or air was injected through a 3cm tube which covered the stem.
Schizogenous aerenchyma(SCHA) was observed in the root tip, lysigenous aerenchyma(LYSIA) was observed in the upper position of the root, and LYSIA and SA were simultaneously observed in the root base. SA was formed inside the LYSIA, and cortex collapse was observed near the root base. O2 concentrations were controlled by N2 or air injections at the position of stem at 0-3 and 3-6cm above water level. N2 injections at the position of stem at 0-3cm above water level resulted in declines of pO2 in the roots from about 14-15 to 3-4kPa. The change in pO2 in the root was affected by removal of SA in stem under water. Air injection at the position of stem 0-3cm above water level after removal of SA in stem didn't make the recovery of the pO2 in the root from 2-4kPa. The light conditions did not affect the changes of pO2 in the root. SCHA, LYSIA and SA developed in order of age of tissue within each adventitious root. The SA in the stem of S. kunstleri positioned near water surface, was investigated as the entry point for atmospheric O2. Keywords: Sustainable forest management ID: 3623148 -
ArticlePlanting bench seedlings in the field: precocity, health, genetic traceability, and homogeneity in rubber plantations
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.The present work aimed to evaluate the establishment index and the initial development of rubber tree seedlings in the field, produced in pine bark substrate on suspended benches in the region of Colina/SP, Votuporanga/SP and Cassilândia/MS. Brazil. The variables evaluated were: establishment index, planting homogeneity, initial field development, and early bleeding. The results showed that the establishment index was higher than 95% due to the large amount of roots of bench seedlings and that this led to greater planting homogeneity. Regarding the development of bench seedlings in the field, this was superior compared to the development of seedlings produced in the ground, and also it was observed a bleeding precocity. In traditional plantations that use ground seedlings, bleeding takes place in the seventh year with an average of 50% of the suitable plants. In a plantation with bench seedlings, there is an anticipation of the maturity period and within six years, more than 70% of the plants are ready to enter into production. Keywords: rubber tree, bench seedling, bleeding anticipation, plant homogeneity. ID: 3624106 -
DocumentHigh-frequency regeneration of plants in vitro from seedling-derived apical bud explants in Tilia mandshurica
XV World Forestry Congress, 2-6 May 2022
2022Also available in:
No results found.Tilia species have taken hold as a crop of interest for both the honey and timber industries, underscoring a need for the development of efficient methods for large-scale propagation. In Tilia species such as T. mandshurica, propagation through seeds is difficult because of a low germination rate (approximately 10-16%) and an extremely hard seed coating that can delay germination for up to two years. Further, cutting propagation is not efficient due to the resulting poor development of root systems. To overcome these difficulties, in vitro culture techniques for plant regeneration have become attractive methods for the propagation of plants. Generally, plant regeneration systems based on apical and axillary bud culture are the most effective method of in vitro propagation
This work was to develop an efficient method for shoot induction and plant regeneration of seedling-derived apical bud explant in Tilia mandshurica. The highest rate (82.2%) of shoot induction was obtained when apical bud explants from juvenile seedlings (5 months old) were cultured on MS medium containing 1.0 mg/L BAP. However, apical bud explants obtained from mature trees (12 years old) did not produce any shoots, even with BAP supplementation. Among the three cytokinins tested for shoot multiplication (BAP, zeatin, and kinetin), BAP was the most effective; the highest number of shoots per explant (2.1) was observed on MS medium supplemented with 1.0 mg/L BAP. For rooting of in vitro-elongated shoots, the highest rooting rate (100%) was observed in half-strength MS medium supplemented with 0.5-1.0 mg/L IBA or 3.0 mg/L NAA. In the acclimatization process, plantlets that were rooted on the IBA (0.5 mg/L)-supplemented medium had the highest survival rate (100%) or root length (18.5 cm). This work showed that a low concentration (0.5 mg/L) of IBA is appropriate for rooting. Keywords: Biodiversity conservation ID: 3622528
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