Exploring Germination, Anatomical and Agronomic Responses of Vigna radiata L. to Temperature and Osmotic Potential via Halothermal Time Model

Vigna radiata L. also known as Mung bean, has been a staple food in various cultures for over three thousand years. In a lab experiment utilizing the halothermal time (HaloTT) model, explored mung bean seed germination under five constant temperatures of 20, 25, 30, 35, and 40°C with five water potentials of 0, –0.2, –0.4, –0.6, and –0.8 MPa. Results showed that the maximum and minimum GP were recorded at 40°C at optimum osmotic potential (0 MPa; control). The highest θHalo and R2 value were documented at 40 and 30°C, respectively. Furthermore, Ѱb(50) = –0.827 MPa and αѱb = 0.415 MPa at kT 0.104 MPa. For Vigna radiata, the cardinal temperatures are documented as Tb = 20°C, Tо = 35°C, and Tc = 40°C. According to the results of antioxidant enzyme the temperature and osmotic potential fluctuation highly affected the enzymes. The highest activity of GPX and APX measured at 35°C in –0.8 MPa and the lowest value of GPX and APX were recorded for 0°C in control (0 MPa). The maximum length of trichome was recorded at 40°C in –0.8 MPa and minimum at 35°C in 0 MPa. Similarly, the maximum width of trichome was recorded at 25°C in –0.2 MPa and minimum at 35°C in –0.4 MPa. Vein islet number was high at 40°C in 0.4 MPa and was lowest at 30°C in –0.2 MPa. Likewise, vein termination number was high at 25°C in –0.2 MPa and was low at 30°C in –0.6 MPa. In conclusion, the germination time course of mung bean in response to NaCl was successfully predicted by the halo thermal time model. Due to its excellent resistance to saltwater, mung bean may be considered a salt tolerant plant and appropriate for growth in semi-arid and arid locations.