Response of Alectra vogelii Benth to Different Crop Root Exudates

Aims: The aim of the study was to evaluate the effect of root exudates from cowpea, groundnut, maize, sorghum and pearl millet genotypes on the germination and attachment of Alectra vogelii. It also aimed to identify functional groups in the powdered root samples that stimulate A. vogelli germination.

Study Design: In the laboratory, a Complete Randomised Design (CRD) replicated six times with six treatments; cowpea (IT18, CBC2 and CBC3); groundnuts (Nyanda), maize (PAN 413), sorghum (Landrace) pearl millet (Landrace) and a negative control (distilled water) were used.

Place and Duration of Study: Department of Agronomy Laboratory, Midlands State University Gweru, Zimbabwe (19°25’S and 29°50’E), between March 2014 to May 2014.

Methodology: To assess the germination and attachment of A. vogelii seeds, three seeds from each genotype were placed on a moistened filter paper in a petri dish with 0,01 g of preconditioned A. vogelii seeds. Identification of functional groups from the powdered root samples of all the crop genotypes using the FT-IR spectroscopy was also done.

Results: Significant differences (P<.05) in the germination of A. vogelii were observed among the crop genotypes. All Cowpea genotypes and groundnut showed no statistical differences and had the highest germination percentages ranging between 72%-80%. The pearl millet landrace (62%) and groundnut (72%) also showed no statistical differences. Sorghum and maize allowed for low germination percentages (29.6% and 24.5%, respectively) Significant differences were noted among attachment counts (P<.05), however, with no statistical differences noted among the three cowpea varieties, which had the highest counts recorded on attachments (123-139 attachments). Significantly low counts on attachment were recorded in groundnut and all the cereals, ranging between 9-15 counts. The FT-IR spectra obtained from the root samples showed differences and similarities as revealed by the peaks (groundnut, CBC2 and PAN 413 - 8 peaks; IT 18, CBC3 and sorghum – 7 peaks; pearl Millet – 5 peaks).

Conclusion: Groundnut and pearl millet genotypes caused effective suicidal germination of A. vogelii seeds and therefore can be used as trap crops in Integrated Weed Management Program. Maize and sorghum did not effectively support germination or attachment. Use of High Performance Liquid Chromatography (HPLC) and mass spectrometry to identify and quantify the strigolactones in each genotype is highly recommended.