Effect of irrigation levels on the physiological responses of petunia cultivars for selection

The selection of drought-tolerant varieties is essential to address the anticipated water stress in plants. This study assessed the drought tolerance of two petunia cultivars (Petunia Grandiflora and Falcon F1 (white). A pot experiment was conducted with the four irrigation levels, which included the irrigation interval of one day (control, T0), three days (T1), five days (T2), and seven days (T3). Under T1, the Grandiflora cultivar produced the tallest plants (43.0 cm). The plant height gradually decreased as the irrigation interval grew longer. Overall, the size of the Grandiflora was observed to be higher than the Falcon F1 cultivar. The Grandiflora cultivar produced the longest roots (6.2 cm) in T0, followed by the Falcon, which had roots with a length of 5.6 cm. The root length of Grandiflora was found to be 5.5 cm and 5.0 cm in T1 and T2, while Falcon F1 produced 5.2 and 4.6 cm roots, respectively. Petunia Grandiflora surpassed Falcon F1 (white) regarding root dry weight for all treatments. In addition, when water was provided after a 3-day gap (T1), the Petunia Grandiflora cultivar produced the highest root-shoot ratio (3.52) using fresh weight. Petunia Grandiflora had the highest chlorophyll concentration of 2.68 mg g−1, followed by the Falcon F1 (white) cultivar in T1. The Grandiflora produced the highest total chlorophyll levels (4.04 mg g−1) when water was added after a one-day break, followed by Falcon F1 (white), which had total chlorophyll values of 3.42 mg g−1 under control compared to other irrigation treatments. Hence, Grandiflora performed the best; therefore, this study will help the cultivators adapt to drought environments using drought-resistant cultivars. Due to this fact, most people buy these flowers as seedlings rather than starting them from seeds, and this research is significant for flower nurseries.