Enhancing germination and growth in Malania oleifera Chun & S. K. Lee seeds through gibberellic acid priming

Abstract

Malania oleifera is an economically and medicinally important endangered forest tree endemic to the karst region of southwestern China, known for the high neurotic acid content of its seed oil. However, it faces challenges of low germination and survival rates due to its dormancy characteristics and high fatty acid content (prone to mildew). This study examines the impact of gibberellic acid (GA₃) on M. oleifera seed germination and the associated physiological and biochemical responses. The results showed that the freshly harvested seeds of M. oleifera remained high (78.33 %) viability but germination was low (50 %) after 5 months of storage. 600 mg/L GA₃ significantly increased the seed germination index, but had no effect on the mildew rate, while 400 mg/L GA₃ reduced the mildew rate. Soluble sugar content was inversely related to GA₃ concentration, while soluble protein levels varied, reaching a minimum at 600 mg/L. Antioxidant (SOD, CAT, POD) and starch-degrading enzyme (α-amylase and β-amylase) activities peaked at this GA₃ concentration. The soluble protein level under 600 mg/L GA₃ treatment was lowest at early stage (S1) and soluble sugar level was lowest at late stage (S2). Antioxidant enzyme and starch-degrading enzyme activities increased with germination, peaking at the final stage (S3). In summary, under the 600 mg/L GA₃ treatment, germination parameters, antioxidant enzymes, and starch - degrading enzymes in M. oleifera seeds were all maximized. Further observation of the four germination stages revealed significant changes in nutrients and enzyme activities, accelerating nutrient consumption and enhancing antioxidant defense.