Genus Curcuma has a long history of traditional uses, ranging from folk medicine to its culinary uses. More than 70 species of Curcuma are distributed throughout the world but extensively cultivate in Asian, Australian and Western African counties. Many phytochemical, pharmacological and molecular studies have been conducted on several Curcuma species worldwide. The interest on its medicinal properties have increased due to the discovery of novel bioactive compounds which possessing wide range of bioactivities such as antioxidant, antiviral, antimicrobial, and anti-inflammation activities. Furthermore, this valuable plant is used as natural dye, insecticide and as a repellent. This review focuses on gathering information regarding genus Curcuma including morphological characteristics, phytochemicals and their biological and pharmacological activities which provide information for further advance research studies.

The investigation of allelopathic effects of different plant species is important to prevent serious crop losses that would arise. The usage of such materials as mulch, cover crops or residues will be useful to implement in integrated weed management strategies of agricultural fields. Therefore, this study was conducted to screen the allelopathic effect of selected plant species using seedlings growth of lettuce (Lactuca sativa L.) as an indicator. The sandwich method was used and 20 mg of dried plant material, resembling the leaf litter, from 27 species were placed in petri dishes. Twenty-eight treatments including the control treatment were arranged in a Completely Randomized Design (CRD). On the fifth day after the establishment of lettuce seeds, hypocotyl length (cm), radicle length (cm) and total height (cm) of seedlings were measured. The inhibitory percentage was calculated and a dendrogram with single linkage was developed. Results revealed that the lowest hypocotyl and radicle lengths with the highest inhibitory percentage were recorded for Ageratum conyzoides, Cassia occidentals and Clidemia hirta when compared to the control treatment (p<0.05). Weed species expressed varying degree of inhibitory effects on growth performances of lettuce seedlings. Further studies need to be carried out to explore the effects of allelopathy on crop plants.

 Abstract-Ashwagandha (Withania sominifera Dunal) is an imperative medicinal crop in herbal industry since time immemorial which roots are in commercial importance. This herb known for its ability to enhance the resistance to stresses, increases stamina and promotes general wellbeing. The changes in the plant growth and quality of the roots mainly depend on different agronomic practices coupled with stage of harvesting. Plants grown under organic and inorganic sources of nutrients were used up to twelve months of sowing for yield analysis and tubers were analyzed for its alkaloid, total fiber and withaferine A contents upto ten months. Highest values for all above phyto constituents were recorded in tubers of organically grown compared to inorganically fertilized plants except crude fiber content and at six months after sowing is the best stage for harvesting to obtain high quality tubers. This is an important study for biochemical standardization of Ashwagandha tubers in commercial processing.

Plants comprising bioactive substances with therapeutic value have progressively become the object of research studies. Many species of the genus Alpinia provide a variety of medicinal properties. This study was undertaken to study the biological activities and physicochemical properties of rhizomes and leaves of six Alpinia species available in Sri Lanka namely, Alpinia malaccensis, Alpinia calcarata, Alpinia galanga, Alpinia nigra, Alpinia calcarata Wild and Alpinia purpurata. Physicochemical parameters will be helpful in standardization for quality, purity and authentication of these medicinal plants. Methanol extracts from rhizomes and leaves were screened for total polyphenol content (TPC), antioxidant activity and α-amylase inhibition activities. Extracted powders were analysed for physicochemical constants such as loss on drying, total ash, acid -insoluble ash and water-soluble ash contents. The TPC of dried leaves of Alpinia calcarata Wild was the highest of all tested as 2.186±0.027 g of GA equivalents per 1 g of dried rhizome. The Methanol extracts of the rhizome and leaf samples of six species showed reasonable antioxidant activity in the DPPH radical scavenging assay. Interestingly the rhizome extracts of Alpinia nigra and Alpinia purpurata exhibited higher α-amylase inhibitory activities (29.417±0.507 and 29.676 ± 0.107 µg/mL respectively) compared with the Acarbose, which is an anti-diabetic drug (28.273 ± 0.615 µg/mL). The results revealed that the Sri Lankan Alpinia species have a potency to be used as a source of antioxidant and anti-diabetic agents and it is important to increase the value of the unexplored medicinal herbs available in Sri Lanka.

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