Muhammad Saiful Ahmad-Hamdani

Allelopathic effect of methanol extracts from Tinospora tuberculata on selected crops and rice weeds

Herbicidal potential of aerial parts of Tinospora tuberculata on germination and seedling growth of seven test plant species, namely rice (Oryza sativa L.); two rice weeds, barnyardgrass (Echinochloa crus-galli L.) and weedy rice (O. sativa f. spontanea); and four vegetable crops, lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), carrot (Daucus carota L.), and cucumber (Cucumis sativus L.) were evaluated. Six concentrations of methanol extract (3.12, 6.25, 12.5, 25, 50, and 100 g L−1) were compared with the control (distilled water). The rate of seed germination and the radicle and hypocotyl length of 7-day-old test plant seedlings were reduced as the concentration of extracts increased compared to the control. Generally, the degree of toxicity of extracts derived from the leaves was more than the extracts derived from the stem. Cluster analysis and the concentrations required for 50% inhibition (defined as EC50) of all parameters showed that radicle growth was more suppressed than germination and hypocotyl growth. Lettuce and carrot were observed as the most sensitive plants while rice showed the highest tolerance to both extracts. Moreover, the dicot target plants were affected more severely than the monocots when treated with leaf extract. The chemical composition of the T. tuberculata methanolic extracts was analyzed by a GC–MS system. A total of 92 and 22 constituents (not previously identified) were found in the leaves and stem, respectively. The results showed that 17 of the 92 components in the leaves, as compared to 4 of 22 compounds in the stem, are known as toxic compounds. These results suggest that T. tuberculata contains a significant source of plant growth inhibitors with potential for the development of future natural herbicide.

Botany, Chemistry, and Pharmaceutical Significance of Sida cordifolia: A Traditional Medicinal Plant

Sida cordifolia Linn. belonging to the family, Malvaceae has been widely employed in traditional medications in many parts of the world including India, Brazil, and other Asian and African countries. The plant is extensively used in the Ayurvedic medicine preparation. There are more than 200 plant species within the genus Sida, which are distributed predominantly in the tropical regions. The correct taxonomic identification is a major concern due to the fact that S. cordifolia looks morphologically similar with its related species. It possesses activity against various human ailments, including cancer, asthma, cough, diarrhea, malaria, gonorrhea, tuberculosis, obesity, ulcer, Parkinson’s disease, urinary infections, and many others. The medical importance of this plant is mainly correlated to the occurrence of diverse biologically active phytochemical compounds such as alkaloids, flavonoids, and steroids. The major compounds include β-phenylamines, 2-carboxylated tryptamines, quinazoline, quinoline, indole, ephedrine, vasicinone, 5-3-isoprenyl flavone, 5,7-dihydroxy-3-isoprenyl flavone, and 6-(isoprenyl)- 3-methoxy- 8-C-β-D-glucosyl-kaempferol 3-O-β-D-glucosyl[1–4]-α-D-glucoside. The literature survey reveals that most of the pharmacological investigations on S. cordifolia are limited to crude plant extracts and few isolated pure compounds. Therefore, there is a need to evaluate many other unexplored bioactive phytoconstituents with evidences so as to justify the traditional usages of S. cordifolia. Furthermore, detailed studies on the action of mechanisms of these isolated compounds supported by clinical research are necessary for validating their application in contemporary medicines. The aim of the present chapter is to provide a detailed information on the ethnobotanical, phytochemical, and pharmacological aspects of S. cordifolia.

Effects of Tinospora tuberculata leaf methanol extract on seedling growth of rice and associated weed species in hydroponic culture

The study was conducted to evaluate the responses of rice and rice weed seedlings (barnyardgrass and weedy rice) at the three-leaf stage to Tinospora tuberculata leaf methanol extract (3.12, 6.25 and 12.5 g L−1) under hydroponic culture. It shows that the leaf methanol extract had various degrees effects depending on target plant species and each tested index (biomass, root length, shoot length, transpiration volume, chlorophyll a, chlorophyll b and carotenoid contents). The effective concentration of the leaf extract capable of reducing 50% of rice growth was higher than those of target weed species. Moreover, the root length was more tolerant to leaf methanol extract in comparison to the other plant parameters measured. A greater reduction was observed in chlorophyll a content compared to chlorophyll b and carotenoid. The results revealed that the reduction of transpiration volume closely coincided with the magnitude of growth inhibition of tested plants. Ultra-fast liquid chromatography analysis revealed 11 of 32 peaks in chemical profile, including benzoic acid, caffeic acid, chlorogenic acid, isoorientin, isovitexin, orientin, p-anisic acid, syringic acid, trans-cinnamic acid, trans-ferulic acid, and vitexin have the same retention time with those peaks of the extract. The amount of compounds was present in the range of between 4 817 and 115.5 mg kg−1 dry weight (DW). The concentration-response bioassay of all 11 individual compounds and their equimolar mixture against the seeds of barnyardgrass revealed their contribution in the allelopahic activity of T. tuberculata leaf extract. The examined compounds and their combination exhibited various degrees of growth inhibitory effects on the early growth of barnyardgrass. Therefore, the specific number, concentration, combination and inhibitory activity of bioactive compounds leads to allelopathy activity of T. tuberculata leaves which could be employable directly as a natural herbicide and its growth inhibitor compounds can be used as a template for producing new herbicides.

Control of weeds in glasshouse and rice field conditions by phytotoxic effects of Tinospora crispa (L.) Hook. f. & Thomson leaves

2 CHILEAN JOURNAL OF AGRICULTURAL RESEARCH 76(1) JANUARY-MARCH 2016 4 OCTOBER DECEMBER 2016 Phytotoxic potential of powder and methanol extract of Tinospora crispa (L.) Hook. f. & Thomson leaves as preand post-emergence applications on the growth of transplanted rice (Oryza sativa L.) and associated weeds were evaluated under glasshouse and field conditions to determine its herbicidal activity as soil additive material in rice fields. In glasshouse study, utilization of leaf powder and leaf extract of T. crispa as pre-emergence application provided a satisfactory weed control, inhibiting seed germination and reducing the growth of germinated seedlings with an increase in the yield of transplanted rice. The magnitude of the phytotoxic effects at the same concentration levels in the test plants was dependent on the application methods (powder and extract), time of application (pre-and post-emergence), concentration and the recipient species. Field experiment consisted of T. crispa leaf powder (1, 2 and 4 t ha), chemical herbicide (pretilachlor + pyribenzoxim at 1 L ha) as positive control and a negative control (no treatment). There was nonsignificant difference between leaf powder-treated plots (2 and 4 t ha doses) and plots that received herbicidal treatment in terms of percentage reduction of emergence and weed DM. In plots amended with 1, 2 and 4 t ha leaf powder, weed dry weight was reduced by nearly 80%, 97% and 99% and total weed seedling density was inhibited by 73%, 94% and 99%, respectively, compared to untreated plots. There was a significant promotion on grain yield, straw dry weight and number of seed per panicle of rice, when treated with leaf powders and chemical herbicide compared with negative control. These results suggest that T. crispa has a significant phytotoxic activity on the germination and growth of weed species in rice fields.

Distribution of weedy rice escape variants in Clearfield Rice Production System

Weedy rice is made up of the undesirable biotypes of rice with early and easy shattering characteristics, which causes a major yield reduction in direct-seeded rice in Malaysia. Thus, a series of survey were conducted in the selected Clearfield rice fields in the four townships, namely, Kampung Sungai Manik, FELCRA Seberang Perak, Kampung Mampas and Kampung Sungai Mati in the Peninsular Malaysia from April 2012 and April 2013 to study the dominance and abundance of weedy rice escaping Clearfield Production System (known as weedy rice escape). The survey was done according to the quantitative survey method by using standardized quadrat. A total of 1240 and 813 weedy rice escapes in dry/off season 2012 and main season 2012 were identified in all surveyed rice fields, respectively. Kampung Mampas indicated the highest dominance of weedy rice escapes, while FELCRA Seberang Perak recorded the lowest dominance in both the planting seasons. From the farmers’ complaint, poor rice management and weeding practices were the major factors that contributed to weedy rice escape in the fields.