Efficacy of Clonal Propagation in Andaman Padauk (Pterocarpus dalbergioides): Augmenting Conservation of an Endemic Ornamental Timber Species of Andaman & Nicobar Islands, India

The population of Andaman padauk (Pterocarpus dalbergioides Roxb.), an endemic ornamental timber species, is fast depleting in the Andaman Islands. Afforestation through seedlings is hindered by low germination and high mortality rates. This study attempts to assess the efficacy of clonal propagation methods to hasten mass multiplication by trying out different combinations of growth hormones, concentration, and dipping duration in semi-hardwood stem cuttings and different combinations of growth hormone concentration and substrate in air layering. Dipping the cuttings in indole-3-butyric acid (IBA) 1,500 ppm for 24 hours and spraying the modified stem-cut layers with IBA 2,000 ppm and binding with top soil and decomposed coir dust turned out to be the best treatment combination for cutting and air layering, respectively. Among the considered factors, the concentration of growth hormone is crucial for cutting, as the performance is enhanced with concentration under a given growth hormone and dipping duration. Similarly, the substrate is crucial for air layering, as modified stem-cut air layers bound with top soil and decomposed coir dust not only achieve the best performance, but also catalyze IBA for further improvement when other substrates remain unresponsive. Successful outcome of both clonal propagation techniques gives hope for disseminating the species across the tropics at global level. Study Implications: Low germination and high mortality render propagation of Pterocarpus dalbergioides through seeds inefficient. This study has revealed an optimal combination of growth hormone and its concentration, dipping duration, and substrate to efficiently propagate this tree through stem cutting and air layering. The findings will help disseminate the highly valuable yet endangered timber species not only in its natural habitat of Andaman Islands but across the globe where there are favorable climatic conditions. As all the species under the pantropical Pterocarpus genus share similar growth and reproductive traits, the optimized treatment combination will be applicable to other species whose existence is threatened in their habitat.

Dynamic Sorption of Methylene Blue (MB) Dye in Continuous Column Using Bio-Sorbent (Ailanthus excelsa Roxb)

Industrial waste containing dye poses a threat to the ecosystem and human as well as aquatic life. Methylene blue (MB, a cationic dye) has been used in excess amounts in textile, pulp and paper, rubber, plastics, cosmetics, pharmaceutical, and food industries. MB dye released in water sources makes the water toxic in nature. So, to remove the dye from wastewater various methods (physical, chemical and biological) are adopted for treatment purposes. Among them, adsorption is found to be more economical and eco-friendlier in comparison to others. Various adsorbents reported have been the literature for the removal of MB dye such as wheat straw, rice husk, cashew nut shell, sawdust, wood, pine needles, green grass, eucalyptus bark, peanut shell, coconut shell, coir dust, etc. In this experimental study, Ailanthus excelsa Roxb. (AER) is utilised for the treatment of MB dye from the wastewater in continuous mode by varying the different parameters viz., bed height, flow rate, and the initial concentration of MB dye. Yoon-Nelson and Clark’s models have been applied to predict the break through curve and to find out the characteristic parameters of column suitable for process design. The study reported that Clark’s model was found to be fit for the breakthrough curve. The findings revealed that Ailanthus excelsa Roxb. has a high adsorption potential, and it could be used to treat dye-containing effluents.

Managing pH of Organic Matrices and New Commercial Substrates for Ornamental Plant Production: A Methodological Approach

Professional peat-free substrates for ornamental plant production are increasingly required by nursery growers. Most promising materials are green compost, coconut coir dust, and woody fibre, used alone or in mixtures. One of the major concerns is pH, usually higher than optimal. In this work, a method based on a three-step procedure was adopted to acidify three organic matrices alone or in mixtures and to individuate the most suitable product, between iron(II) sulphate 7-hydrate and elemental sulphur chips. Firstly, the determination of the buffering capacity by dilution with sulphuric acid was carried out to determine dosages. Afterwards, an incubation trial of 84 (iron(II) sulphate) or 120 days (sulphur chips) was conducted on matrices and substrate mixtures with calculated doses in a climatic chamber maintained at 21 °C. Iron(II) sulphate resulted not suitable because it caused a rapid, but not lasting, pH lowering and an excessive electrical conductivity (EC) increase. Sulphur chips could instead guarantee an adequate and lasting pH lowering. These results were then validated in the open field trial on matrices and substrates. The proposed acidification methodology could be considered in developing new substrates, but the rapidity of pH acidification and EC increase on plant and mineral nutrition should be further investigated.

SUCCESSFUL INCORPORATION OF CRUSHED PINE (PINUS CARIBAEA) LEAVES INTO COCONUT COIR DUST NURSERY MEDIUM FOR VEGETABLE SEEDLING PRODUCTION

Different soilless media are used in vegetable nurseries for high quality seedling production. In the current research, potential of incorporating crushed pine leaves (CPL) into coconut coir dust (CCD) as an economical and sustainable media alternative for vegetable nursery trays, was investigated. CPL was used as mixtures with CCD at the ratios of 4:0, 3:1, 2:2, 1:3 and 0:4 (Treatment 1-5). Suitability of each treatment as soilless medium was investigated by evaluating their physical and chemical properties as well as biodegradability. Growth performances of the seedlings grown in the treatments were evaluated using brinjal, capsicum, ‘elabatu’ (Solanuminsanum), knolkhol and tomato. The highest water holding capacity, pH and bio-degradability (6.21ml/g; 7.38; 12.6%) were observed in CCD and lowest values were in CPL (1.30ml/g; 5.18; 8.6%). The highest air porosity and bulk density were in CPL (36.7%, 0.32g/cm3) and the lowest were in CCD (2%, 0.23g/cm3). Mixing of these two materials brought those parameters to moderate values which were appropriate for vigorous plant growth. Capsicum, knolkhol and tomato showed higher seedling vigour index, growth rate and root lengths in T2 and T3 mixtures. Brinjal showed the highest values of growth rate and root length in T3 and T4, and seedling vigour index in T3. ‘Elabatu’ showed highest values of growth rate and root length in T4 and T5, and seedling vigour index only in T4. The result concludes that, CPL can be used in nursery medium without any harm to the plants but incorporation of CPL with CCD improves the properties of growth media and assures better seedling growth.

Efficient Water Management for Cymbidium Grown in Coir Dust Using a Soil Moisture Sensor-Based Automated Irrigation System

Efficient long-term management for the production of high-quality Cymbidium plants is required as these orchids generally require 3–4 years of vegetative growth to allow flowering. This study was conducted to investigate the optimal substrate moisture levels to efficiently produce young cymbidium using a soil moisture sensor-based automated irrigation system over 42 weeks of vegetative growth. One-year-old cymbidium “Hoshino Shizuku” plantlets were grown in coir dust substrate at four levels of volumetric water content (0.25, 0.35, 0.45, and 0.55 m3·m−3). At harvest, the numbers of leaves and pseudobulbs, and the chlorophyll content of the cymbidiums did not differ among the four θ threshold treatments. However, plants grown at 0.25 m3·m−3 had significantly smaller leaves, pseudobulbs, and biomass than those at the other θ threshold treatments. Although the lower θ decreased the photosynthetic parameters, such as the net photosynthesis, stomatal conductance, and transpiration, there were no differences in the maximum quantum yield of photosystem II, indicating that the reduction in net photosynthesis is mostly mediated by stomatal closure. Although the net photosynthesis at θ of 0.35 m3·m−3 was also lower than that at 0.55 m3·m−3 treatment, biomass was significantly lower only at 0.25 m3·m−3 treatment, suggesting that a critical growth reduction by the water deficit occurred for the cymbidium at 0.25 m3·m−3. As the θ threshold increased, the total irrigation amount significantly increased, which inversely decreased the water use efficiency. Although the plants grown at 0.25 m3·m−3 had the highest water use efficiency (WUE) and substrate electrical conductivity they showed significantly reduced growth compared to other θ threshold treatments, and thus this was not a reliable θ threshold level for producing high (visual) quality cymbidium. Overall, the 0.35 and 0.45 m3·m−3 threshold treatments provided appropriate moisture levels for high-quality cymbidium production with high water use efficiency.

The effect of vegetal mulching on soil surface temperature in semiarid Brazil

Summary Understanding the temporal and spatial dynamic of soil temperature is crucial for agriculture, since it affects soil evaporation and soil biological activity, influencing seed germination, root growth and absorption of water and nutrients by crops, and ultimately the runoff process. Mulching is one of the most applied soil and water conservation method for soil moisture and soil temperature variations control. This study aimed to investigate the influence of three different mulch types (dried elephant grass straw, dried cashew tree leaves and coconut powder or coir dust), applied with three area densities (2, 4 and 8 t ha−1), on the soil surface temperature, under field conditions in the Brazilian semiarid region. Soil temperature monitoring was carried out using thermocouple sensors and an infrared camera in the Brazilian semiarid region. Results show that mulching provided a buffer zone, dampened soil temperature fluctuations over time, mainly for the 8 t ha−1 density. Mulching reduced soil temperature during the hotter period of the day and increased soil temperature during the night period.