Shepherd’s purse, a beloved traditional wild vegetable with both medicinal and edible values, has a broad market prospect. However, frequent droughts in recent years have posed a serious threat to its industry development. A study on the impact of simulated drought stress and gibberellin on shepherd’s purse seed germination brings new insights.
Mild drought stress, specifically simulated by 5% PEG-6000, can significantly promote shepherd’s purse seed germination. Compared with distilled water (ck1), the germination rate (83.89%), germination potential (53.89%), germination index (49.23), vigor index (3.53) and radicle length (1.18 cm) increased by 1.67 percentage points, 1.11 percentage points, 1.95%, 13.14% and 90.32% respectively. This may be because low-content PEG-6000 slows down the water absorption rate of seeds, improves the internal metabolic process, and promotes the synthesis and transformation of substances in seeds.
However, as the content of PEG-6000 increases, the germination indicators of shepherd’s purse seeds gradually decrease. Under the treatment of 15% and higher concentrations of PEG-6000, all indicators of shepherd’s purse seed germination are significantly lower than that of distilled water (ck1).
When it comes to the effect of gibberellin on shepherd’s purse seed germination under drought stress, under the simulated drought stress of 15% PEG-6000, 0.2 g/L gibberellin treatment achieves the best germination effect. Its germination rate, germination potential and vigor index are significantly higher than that of distilled water (ck2). Low concentrations of gibberellin (0.1 g/L, 0.2 g/L, 0.3 g/L) have a significant alleviating effect on the germination of shepherd’s purse seeds under drought stress, while high concentrations (0.4 g/L, 0.5 g/L) may interact with drought stress to produce a dual inhibitory effect on seed germination.
Regression analysis shows that there is a parabolic relationship between gibberellin concentration and seed vigor index. When the mass concentration of gibberellin is 0.1750 g/L, the seed vigor index reaches the maximum value (2.55).
In conclusion, appropriate concentration of exogenous gibberellin can effectively alleviate the negative impact of drought stress on shepherd’s purse seed germination. However, its application effect is affected by many factors such as shepherd’s purse variety, climate conditions, seed soaking time and drought degree, so the results need to be verified by multi regional repeated experiments before large-scale promotion and application. In addition, the internal physiological mechanism of gibberellin improving the germination ability of shepherd’s purse seeds under drought stress needs further exploration.