Cuscuta campestris Yuncker, commonly known as Golden dodder is an annual problematic parasitic weed in abandoned and derelict areas in Malaysia. The weed is leafless plant, glabrous, yellow-white in colour, with haustoria, sucker-like attachments to the aerial parts of a wide range of host plants. This study was instituted to assess the allelopathic potentials of C. campestris on lettuce and radish as test plants. Three types of treatment using aqueous extract of fresh (fc), and dried s (dc) and ethanol extract of dried C. campestris (ec) were assayed for their allelopathic effects on radish (Raphanus sativus) and lettuce (Lactuca sativa) seeds. These extracts reduced seed germination, root and shoot lengths of both radish and lettuce. The roots of radish were more sensitive vis-à-vis the shoots when exposed to fc, while shoots were more sensitive than roots when exposed to dc. Dose-mediated differences in shoot and root lengths of radish were registered when treated with ec. The roots of lettuce were more sensitive compared with the shoots when exposed to ec, while no measurable effect was observed when roots and shoots of lettuce were exposed to fc and dc. The results demonstrated the allelopathic effects of dodder on the tested host plants. The potentials of these extracts and their chemical constituents as bioactive ingredients for new herbicides are implied.

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A crude methanol extract of Goniothalamus andersonii J. Sinclair strongly inhibited elongation of lettuce (Lactuca sativa L.) radicles. We conducted bioassayguided purification of G. andersonii bark extract and obtained goniothalamin as the major bioactive compound. Its EC 50 values against elongation of lettuce radicles and hypocotyls were 50 and 125 µmol L −1 , respectively. Among the six species tested, timothy was the most sensitive to goniothalamin. Quantification of this compound in other Goniothalamus species suggested that the plant inhibitory activity of this genus is explainable by goniothalamin, with G. calcareus as an exception.

Goniothalamin produced by the Malaysian medicinal plant, Goniothalamus andersonii J. Sinclair, strongly inhibits plant growth. However, its mode of action has not been characterized at the gene expression level. We conducted DNA microarray assay to analyze the changes in early gene responses of Arabidopsis thaliana seedlings. After a 6-h exposure to goniothalamin, we observed an upregulation of genes highly associated with heat response, and 22 heat shock protein (AtHSP) genes were upregulated more than 50 fold. Together with these genes, we observed upregulation of the genes related to oxidative stress and protein folding. Also, the genes related to cell wall modification and cell growth, expansin (AtEXPA) genes, were significantly downregulated. The results suggested that goniothalamin induces oxidative stresses and inhibits the expression of cell wall-associated proteins resulting in growth inhibition of Arabidopsis seedlings.

Product efficacy testing during 2006 to 2010 with SBAJA (a novel scientifically formulated foliar-spray growth and yield enhancer) in the greenhouse and multi-location field trials registered measurable increase in chlorophyll contents, robust and healthier crop growth and increased yield and biomass production. In field trial, rice plants receiving normal NPK fertilizer at the rates of 100:50:30 served as control and spray treated with SBAJA at 40 and 60 days after sowing (DAS). All the experiments were laid out in Randomized Complete Block (RCB) Design and replicated five times. Tiller number and panicle characteristics; length, weight, number of grains, number of filled grains were significantly increased with 1:300 SBAJA treatment. In addition, 1000 grain weight and rice yield increased significantly with SBAJA treatments. Normal fertilizer applications in field trials augmented with SBAJA in 2008-2010 in the Selangor North West Project (SNWP), registered measurable increase in rice yields by 25-30% from 6.2 -6.5 tons/ha to 7.8 -8.9 tons/ha. It is concluded that foliar spraying with SBAJA at 40 and 60 days after sowing increased growth and yield of rice under green house and field conditions.