TITLE:
The Allelopathic Potential of Conocarpus lancifolius (Engl.) Leaves on Dicot (Vigna sinensis L.), Monocot (Zea mays L.) and Soil-Borne Pathogenic Fungi
AUTHORS:
Aisha H. Al-Shatti, Amina Redha, Patrice Suleman, Redha Al-Hasan
KEYWORDS:
Allelopathy, Allelochemicals, Photosynthesis, Biocontrol, Conocarpus lancifolius
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.19,
September
16,
2014
ABSTRACT: Aqueous leaf extract and pulverized leaf tissue were tested for
allelopathic effects on seed germination, seedling growth traits and net
photosynthesis of corn (Zea mays L.)
and bean (Vigna sinensis L.) The
chemical constituents of the leaf extract were determined by GC-MS and the
efficacy of the leaf extract to control some soil-borne fungal pathogens was
also evaluated. The leaf extract inhibited germination, radicle and plumule
lengths, root and shoot growth, chlorophyll content, photosynthesis and
nutrient uptake in both crops. In corn and bean plants growth inhibition was
proportional to the concentrations of the extracts (2.5% - 7.5%). Seed
germination was associated with water uptake and the solute potential of the
extracts. Leaf extracts also reduced of chlorophyll content, and stressed
photosynthetic function by reducing photochemical efficiency (Fv/Fm) and
electron transport rate (ETR) of PS II in corn and bean plants. Corn was more
tolerant to the leaf extract than bean plants. The GC-MS analysis detected
thirty one and thirty three compounds in winter and summer leaf extracts,
respectively. The majority was phenolic compounds. Mycelia growth of Fusarium oxysporum f. sp. lycopersicon, Sclerotinia sclerotiorum, and Rhizoctonia
solani was inhibited and in 10% extract the fungi died. The extract
however, had no effect on Trichoderma
harzianum. Leaf extract of C.
lancifolius exhibited both herbicidal and fungicidal properties but cannot
be recommended for biological control of soil borne fungal plant pathogens
because it has the potential to physiologically stress or damage cultivated
plants or crops.