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Physalis peruviana holds significant economic value, making it crucial to determine optimal cultivation conditions, particularly concerning seed germination under varying water and temperature conditions. Therefore, this study aimed to assess the impacts of heat and water stress on the germination and vigor of P. peruviana seeds. The study was divided into two trials: the first examined the effect of constant temperatures of 10, 15, 20, 25, 30, 35, and 40 °C and alternating temperatures of 20 °C during the dark period and 30 °C during the light period (control) on seed germination and vigor. The second trial investigated germination and vigor under different water and thermal conditions using various osmotic potentials (0; −0.3; −0.6; and −0.9 MPa) and two temperatures (constant 30 °C and alternating 20 °C during the dark period and 30 °C during the light period). Both trials used a 16 h photoperiod. The germination tests revealed optimal (30 °C), moderate (20/30 °C), minimal (20 °C), and inhibited (40 °C) temperatures for the species’ germination. It was found that the first germination count could be conducted on the seventh day after sowing. Low water availability had negative effects on seed germination and vigor, especially at osmotic potentials below −0.45 and −0.61 MPa, combined with temperatures of 30 and 20/30 °C, respectively. Severe water stress, with osmotic potentials equal to or below −0.9 MPa, completely inhibited seed germination and vigor. Reduction in water potential and increased temperature resulted in a significant decrease in the percentage, speed, and quality of P. peruviana germination. These findings indicate that the species does not tolerate extreme temperatures, whether low (less than 15 °C) or high (greater than 35 °C), nor water stress with osmotic potentials lower than −0.45 MPa, much less the combination of these factors.
Freitas et al. (Tue,) studied this question.