An inventory of multipurpose Avenue trees of Urban Chandigarh, India

Trees in urban ecosystems play a very significant role in environmental protection by checking air and noise pollntants, abating wind, and handling many other functions, in India, Chandigarh is the mosl modern and em,iromnentally safe city and qualifies to be called a GREEN CITY because of its rich tree component. This is so in spite of its high population density, currently over 9,443 people per square kin, perhaps the highest in the country. It has nearly 42,000 trees growing along the roads in a systematic manner. The drives are identified with the type of multipurpose tree species. Nearly 66 tree species (over half indigenous) are seen along the roadsides; these trees provide shade, timber, fuel, fodder, fruit, medicine, and other benefits. In addition, the city is decorated with 11 gardens harboring over 200 types of trees

Phytotoxic potential of Populus deltoides Bartr. ex Marsh. I. Comparative contribution of different parts

The aqueous leachates prepared from different parts of Populus deltoides retard the germination and growth of mung bean (Phaseolus anrenus) However, the impact varied depending upon concentration and tree part used. The leachates prepared from leaves exhibited strong inhibitory potential compared to other parts. viz. bark. buds. root and stem. Since diflerent parts possess different water contents. The leachates prepared from fresh tree parts were equalized on the basis of dry weights. The content of organic component of leachable allelochemics (aglycones) depict a great variability with maximum amount being extracted from leaves and least from Stem. The relative allelopathic potentiality of each part was concomitant with respective amounts of aglycones in each part

Nutritional composition and antioxidant capacity of Urtica hyperborea: A phytofood of Trans-Himalayan region of Ladakh, India

Urtica hyperborea Jacquem. ex Wedd., a perennial plant of Urticaceae family is considered as a wild vegetable in the mountainous region of Ladakh. Due to its application in many forms of traditional culinary in every household during the harsh winter season, the plant ensures the food security. However, the nutritional composition and phytochemical analysis of U. hyperborea responsible for these beneficial features have not been explored widely. The present study aims to determine the nutritional composition (e.g., macromolecules, pigments, minerals, phenolics and flavonoid contents), antioxidant activity and the phytochemical analysis of this plant species present in Ladakh, India. The radical scavenging and antioxidant potential of the plant were evaluated by assays like 2,2‒diphenyl‒1‒picrylhydrazyl (DPPH), hydrogen peroxide (H2O2), hydroxyl (ºOH), and ferric ion reducing antioxidant power (FRAP) for different extracts prepared in water, methanol, ethyl acetate, and petroleum ether. Macromolecules such as protein, carbohydrate, total phenolic and flavonoid contents in U. hyperborea were found to be 62.28±6.67, 170.80±3.98, 24.47±0.39 and 5.43±0.97 mg g-1, respectively. Similarly, dried powder of U. hyperborea was found to be rich in different mineral contents such as potassium, magnesium, sodium, manganese, zinc and iron. Among the various solvents used for exploring scavenging and antioxidant potential, aqueous extracts showed highest activity with 79.2% in DPPH assay as compared to other extracts. Similar trend was observed for other assays where aqueous extracts exhibited higher activity followed by methanolic, ethyl acetate and petroleum ether extracts. Significant positive linear correlations were observed between the radical scavenging/antioxidant activity of aqueous extracts and their content of phenolic/flavonoid compounds. The identification of phenolic compounds such as coumarin, quercetin, and ferulic acid confirm the antioxidative nature of the plant. Overall, rich macromolecule and mineral contents, as well as higher radical scavenging/antioxidant activities in aqueous extracts of U. hyperborea revealed that the plant has significant potential to be utilized as a phytofood source in harsh environmental conditions

Chemical composition and inhibitory activity of essential oil from decaying leaves of Eucalyptus citriodora

A study was undertaken to explore the content and composition of volatile oil from decaying leaves of lemon-scented eucalypt (Eucalyptus citriodora Hook.) not analyzed earlier. GC and GC-MS analysis of the oil (yield 0.6%) revealed the monoterpenoid nature with citronellal (52.2%), citronellol (12.3%) and isoisopulegol (11.9%) as the major constituents. Overall, 17 components were identified that accounted for over 94% of the decaying leaf oil. Surprisingly, the decaying leaf oil contained nearly 1.8% of trans-rose oxide, which is generally absent in eucalypt essential oil. Decaying leaf oil and its major 2 components (citronellal and citronellol) inhibited the germination and root elongation of two weeds Ð Cassia occidentalis (broad-leaved) and Echinochloa crus-galli (grassy weed). Based on the dose-response studies, I 50 values were determined for decaying leaf oil and the effect was more on germination only of broad-leaved weed (C. occidentalis), whereas that of citronellal and citronellol were on germination as well as root length of E. crus-galli (grassy weed). Based on I 50 values it was observed that citronellal was more phytotoxic and germination inhibiting in nature, whereas citronellol was a more potent root inhibitor, thereby indicating a possible different mode of action. The study concludes that decaying leaf oil hold a good commercial value for exploitation as weed management agent

Eucalypt oils for the control of Parthenium (Parthenium hysterophorus L.)

Eucalypt oils from Eucalyptus globulus and E. citriodora exert deleterious effects on Parthenium hysterophorus - a noxious weed. The germination of the weed was inhibited and the chlorophyll content and cellular respiration of the mature plants exposed to eucalypt oils were reduced drastically. This was accompanied by increased water loss resulting in complete wilting of the plants after 15 days of exposure to volatile oils. The oil from E. citriodora was more effective in causing injury to the weed compared to E. globulus oil. Efforts should, therefore, be made to devise a strategy for controlling the weed through eucalypt oils

Allelopathic effect of two volatile monoterpenes against bill goat weed (Ageratum conyzoides L.)

A study was conducted to assess the allelopathic effect of two volatile monoterpenes viz. cineole and citronellol on Ageratum conyzoides with a view to explore the possibility of their exploitation for future weed management. Both the monoterpenes severely affected the germination, speed of germination, seedling growth, chlorophyll content and respiratory activity. After two weeks of exposure, the weed plants wilted. Out of the two monoterpenes, cineole was more toxic in causing injury to the weed

Autotoxicity: concept, organisms, and ecological significance

The present review deals with the phenomenon of autotoxicity - a type of intraspecific allelopathy, where a plant species inhibits the growth of its own kind through the release of toxic chemicals into the environment. This phenomenon has been reported to occur in a number of weeds and crop plants in agroecosystem and wastelands causing the soil sickness. Besides, it plays a significant role in the orchards (of apple, pear, grapes, etc.) where it is the major reason of the replant problem, natural forests and coffee and tea plantations causing the regeneration problems. Not only the higher plants, but even some ferns and algae are also reported to show this phenomenon. Some plants have even developed extensive mechanisms to overcome this phenomenon, whereas the others have adapted to it by making structural and ecological changes providing to them a competitive ecological advantage over the others. Although autotoxicity is a natural phenomena providing selective benefit to the plant, yet the chemicals responsible for this have good potential for weed and pest management

Allelopathy in Agroecosystems: an overview

Allelopathy plays an important role in the agroecosys-tems leading to a wide array of interactions between crop-crop, crop-weed and tree-crops. Generally, these interactions are harmful to the receiver plants but provide a selective benefit to the donor. Soil microbes play a key role in determining such interactions as they not only alter the nature of allelopathic interactions but also modify the expression of allelochemicals. Soil sickness problem in the croplands could also be attributed to the allelopathic property or even the autotoxicity. The allelochemicals released largely by the plant residues that are left in the fields after the harvest of crops add to the multifarious problems. If properly managed, these residues could be used for controlling weeds and pests. As is true for any chemical based response, allelopathic interactions are also concentration specific. The promotory functions that are inbuilt need to be worked out and exploited. Now a days allelopathic interactions, in general, and the allelochemicals, in particular, are viewed as an important tool for sustainable weed and pest management, and disease control. In this direction, a number of strategies like use of cover or smother or companion crops for weed management, direct use of allelochemicals as natural pesticides, and even the transfer of allelopathic traits/principles to modern day cultivars are being adopted. The purified allelochemicals and/or their derivatives and even the compounds synthesized on their chemistry can be used as novel agrochemicals for sustainable management in an eco-friendly manner. The present paper aims to discuss all the above mentioned roles and aspects of allelopathy in the agroecosystems