Germination and growth responses to water stress of three agroforestry tree species from Bangladesh

Abstract

Globally, tree plantations are considered one of the most effective solutions in tackling the climate crisis, and by incorporating trees, agroforestry plays an essential role in mitigating climate change. However, the productivity and sustainability of this commendable solution are often impeded by the wide range of abiotic stresses, including drought. Species selection is always considered as one of the major challenges in a drought-prone area to ensure maximum productivity and halting tree mortality. In this study, seedling responses such as germination, survival, and growth were examined for Swietenia macrophylla, Acacia nilotica and Pithecellobium dulce in variable soil moisture regimes with 100%, 50% and 25% soil water content (SWC). Despite complete failure of germination at 25% SWC, S. macrophylla showed a significantly higher germination percent at both 100% and 50% SWCs (p < 0.05). Irrespective of species, the 25% SWC showed reductions of germination percent, survivability and total dry biomass in comparison with the higher moisture regimes. The study also showed that P. dulce and A. nilotica seedlings were able to survive and maintain growth at low moisture regimes. The significant interaction effect in most parameters highlighted that both species and moisture regimes played an important role in germination and total biomass production, but this interaction had an insignificant effect on the survivability of all species. The result from this study highlights that species-specific responses to water stress could contribute to the species selection policies in drought-prone areas.