Ecophysiological Response and Alkaline Soil Tolerance of Rafflesia philippensis for Sustainable Urban Greening in the Philippines: A Systematic Review

Rafflesia philippensis is an extremely rare and endemic parasite in the Philippines that is nourished entirely by the host plant, Tetrastigma spp. subjected to particular soil conditions. This systematic analysis attempts to put the literature on the ecophysiology and soil tolerance of Rafflesia philippensis together, focusing more on alkaline-related responses occurring in disturbed and urbanized environments. Thus, field surveys, experiments, and soil analyses suggest that soil pH may critically influence the processes of nutrient solubilization, host plant vigor, and microbe-mediated processes. It is found that acidic forest soils (pH 5.0–6.5) with high organic matter contents and diverse microbial communities are more congenial to the growth and reproduction of Tetrastigma spp., thereby aiding the growth and reproduction of Rafflesia philippensis. In contrast, alkaline disturbed soils (pH 7.5-8.5) are associated with reduced nutrient availability, physiological impairment, and dysfunction in beneficial microbial interactions, which adversely affects flowering and tuber formation in Rafflesia philippensis. Enhancement of the restoration of suitable habitat conditions for this species and sustainable urban greening might involve soil amelioration, particularly organic matter addition, biochar application, and inoculation with the required organisms. Land use and soil degradation policies, especially in urban settings, ought to incorporate habitat restoration approaches to ameliorate the hindering effects that soil alkalinization poses to vulnerable species. Further research is intended to monitor the long-term impact of restoring habitats, evaluate soil amendments empirically, and study host- parasite interactions further so that the conservation of Rafflesia philippensis in disturbed settings may be supported.