Effect of NaCl on Orobanche spp and Striga hermonthica seeds germination during and after conditioning

The parasitic plants Orobanche and Striga spp. are holo- and hemi-parasites respectively, which largely depend on a host plant to obtain their nutrients and water. The objective of this study was to investigate the effect of NaCl on Orobanche and Striga seed germination under laboratory condition. Seeds of Orobanche minor were exposed to 50, 75, 100 and 150 mM NaCl solutions during or after conditioning period (for 7 days) and induced to germinate by a synthetic germination stimulant GR24. As a result, seed germination was decreased significantly with the increase in salt solution concentration during conditioning. Significant reduction in O. minor seed germination was observed at highest NaCl level (150 mM). It reduced germination by 92% as compared to the corresponding control. On the other hands, germination response of O. minor seeds conditioned in water and then treated with mixture of GR24 and NaCl 1: 1 (v/v) was studied, and results displayed that germination of O. minor seeds was inhibited with increasing NaCl concentrations. Seeds treated with 150 mM, exhibited reduced germination by 77% as compared with control. With respect to O. crenata and Striga, results showed that all concentrations of NaCl decrease seeds germination. Of all NaCl concentration tested, 100 mM displayed the most inhibitory effect. Osmotic potential may significantly affect germination and radicle elongation of parasitic weeds.