SKUAST Journal of Research

Premature bolting limits the yield and quality of lettuce (Lactuca sativa L.). This study assessed the effects of paclobutrazol (PBZ) application (50 ppm), growing systems (soil-based and hydroponic), and modes of application (seed priming, root dip, foliar spray) on bolting and flowering timing. Conducted during 2023–2024 at SKUAST-K, the experiment followed a factorial randomized complete block design. PBZ-treated plants showed delayed flower initiation (89.4 days), bolting (95.6 days), and anthesis (102.3 days) compared to controls (85.6, 92.6, and 98.9 days, respectively). Hydroponic-grown lettuce delayed flowering (88.35 days) compared to soil-grown (86.65 days). Foliar application delayed flowering (92.7 days), bolting (101.8 days), and anthesis (109.9 days) more effectively than seed priming or root dip. The combined treatment of PBZ with hydroponics and foliar spray (P2×S1×M3) achieved the most delayed flower initiation (94.9 days), bolting (103.2 days), and anthesis (111.2 days). Delays in bolting and flowering were statistically significant (C.D. at p≤0.05: 0.27–0.36 days). These results demonstrate that PBZ, especially via foliar application in hydroponics, can substantially extend the vegetative phase, improving stress tolerance and market quality in lettuce.