Efficacy of scarification treatments on release of seed coat imposed dormancy in five wild species of genus Corchorus

Abstract

In India, six wild species of the genus Corchorus, namely C. pseudo-olitorius, C. aestuans, C. trilocularis, C. fascicularis, C. tridens and C. pseudo-capsularis are known to occur in diverse ecological conditions. These wild species are very important due to the presence of genetic variability for yield attributing traits and resistance to biotic stress. Seed of wild Corchorus species exhibit 100% seed dormancy due to hardseededness. Seed dormancy in wild species limits their scope of utilization in breeding programmes due to failure of germination in a desired period. Seed dormancy also creates problems in maintenance of these wild germplasms. Various types of scarification treatments, like mechanical scarification with sandpaper, hot water treatments (at 80 °C) and acid scarification with concentrated H2SO4, have been reported by several workers to remove hardseededness in wild Corchorus species. The present investigation was carried out to find out the effects of eighteen different scarification treatments including solo and some specific combinations in completely randomized design to identify the best suited scarification protocols in five wild Corchorus species. The study revealed that acid scarification with concentrated H2SO4 significantly improved seed germination but scarification with concentrated H2SO4 for 5 and 10 min prior to hot water treatment (2 min at 100 °C) resulted in the highest seed germination in C. pseudo-olitorius (90%) and C. aestuans (92%) respectively. Acid scarification in concentrated HCl for 10 min prior to hot water treatment (2 min at 100 °C) provided the significantly highest seed germination in both C. tridens (84%) and C. trilocularis (71%). However, acid scarification with H2SO4 for 30 min was capable of providing maximum seed germination (56%) in C. fascicularis. These species-specific treatment combinations can be utilized to maximise seed germination in wild Corchorus species.