ABA production in response to the desiccation of recalcitrant embryos of Artocarpus heterophyllus LAM. and Artocarpus hirsutus LAM

The phytohormone, ABA plays a vital role in the growth and development of plants. The hormone is generally associated with seed dormancy and it is reported to be involved in desiccation tolerance in orthodox seeds. There is no conclusive information about the role of ABA in recalcitrant species. The present investigation was aimed at understanding the changes in ABA level during the desiccation of recalcitrant embryos of Artocarpus heterophyllus Lam. and Artocarpus hirsutus Lam. A significant positive correlation has been established between moisture content and ABA level in the local cultivars of Artocarpus heterophyllus (viz., varikka and koozha). A comparatively high level of ABA could be observed in the mature embryos of both cultivars of Artocarpus heterophyllus. Vivipary has been observed in these cultivars even under elevated levels of ABA. The ABA level drastically decreased during desiccation of embryos. However, the embryos could tolerate mild desiccation even under low level of ABA. A different trend in ABA could be observed in Artocarpus hirsutus in which the embryos maintained extremely low level of ABA and could tolerate desiccation better than Artocarpus heterophyllus. No significant correlation has been established between moisture content and ABA level in this species. Vivipary could not be observed in Artocarpus hirsute seven under low levels of ABA. Results suggest that vivipary cannot be attributed to the low level of ABA and it is not the sole factor in providing desiccation tolerance in orthodox seeds.