Passion fruit is known to be sensitive to drought, and in order to study the physiological and biochemical changes that occur in passion fruit seedlings under drought stress, a hypertonic polyethylene glycol (PEG) solution (5%, 10%, 15%, and 20%) was used to simulate drought stress in passion fruit seedlings. We explored the physiological changes in passion fruit seedlings under drought stress induced by PEG to elucidate their response to drought stress and provide a theoretical basis for drought-resistant cultivation of passion fruit seedlings. The results show that drought stress induced by PEG had a significant effect on the growth and physiological indices of passion fruit. Drought stress significantly decreased fresh weight, chlorophyll content, and root vitality. Conversely, the contents of soluble protein (SP), proline (Pro), and malondialdehyde (MDA) increased gradually with the increasing PEG concentration and prolonged stress duration. After nine days, the SP, Pro and MDA contents were higher in passion fruit leaves and roots under 20% PEG treatments compared with the control. Additionally, with the increase in drought time, the activities of antioxidant enzymes such as peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) showed an increasing trend and then a decreasing trend, and they reached the highest value at the sixth day of drought stress. After rehydration, SP, Pro and MDA contents in the leaves and roots of passion fruit seedlings was reduced. Among all the stress treatments, 20% PEG had the most significant effect on passion fruit seedlings. Therefore, our study demonstrated sensitive concentrations of PEG to simulate drought stress on passion fruit and revealed the physiological adaptability of passion fruit to drought stress.

Vaccinium uliginosum L. is a wild fruit tree, mainly distributed in the extremely cold climate region of China, such as the Greater Khingan Mountains, Lesser Khingan Mountains, and Changbai Mountains. Most fruit trees are largely unsustainable in these regions, but wild V. uliginosum thrives in the region. Therefore, it is necessary to protect the precious wild V. uliginosum resources. With the effect of global warming, the suitable habitat of V. uliginosum has also changed. A total of 287 pieces of data with 22 environmental variables were collected on the geographical distribution of wild V. uliginosum. The Maxent model was applied to predict the potential distribution of V. uliginosum in China under different climate scenarios (Socioeconomic Pathways 1-2.6 (SSP1-2.6), SSP2-4.5, SSP3-7.0 and SSP5-8.5) in the current and future two periods (the 2050s and 2070s). The predicted results show that the distribution and area of the suitable area-change range is small. The results show that the cumulative contribution rates of BIO07 (annual temperature range), BIO12 (annual precipitation), and BIO10 (mean temperature of warmest quarter) reach 74.1%, indicating that temperature and precipitation are the key factors affecting the distribution of V. uliginosum. This study can provide a reference for relevant departments to take conservation measures with respect to climate change and the adaptation of V. uliginosum to habitat changes.