The effects of thermotherapy and sodium hypochlorite treatments on pepino seed germination, a crucial step in breeding programmes

We evaluated the effects of treatments with thermotherapy (80 degrees C for 24 h) and dipping in sodium hypochlorite (NaOCl; 0.8% for 10 min) on the g ermination percentage, germination rate, vigour index and ToMV inactivation of seeds from three pepino (Solanum muricatum) accessions (96-5, B-2 and O V-8) and two wild relatives (S. tabanoense EC-26 and S. caripense EC-40). T hermotherapy de creased the germination percentage (especially in the wild species), germination rate in wild species but not in cultivated pepino, an d vigour index in all cases. Sodium hypochlorite increased germination, exc ept for non-thermotreated seeds of OV-8, improved the germination rate in w ild species and the vigour index in all cases except for non thermotreated OV-8. Seed coats were altered by both treatments, especially by NaOCl. Ther motherapy was totally effective in the inactivation of seed-borne ToMV, whi le NaOCl was not. Thermotherapy combined with NaOCl allows effective seed d isinfection of S. muricatum seeds without negatively affecting seed germina tion. For the wild species, although thermotherapy reduces germination, the higher number of seeds per fruit in these species reduces the magnitude of the problem. Even when no disinfection is necessary, treatments with NaOCl are always advisable as they improve germination.