Effects of soil warming and nitrogen fertilization on leaf physiology of Pinus tabulaeformis seedlings

Abstract

The paper mainly studied the short-term influences of experimental warming, nitrogen addition, and their combination on physiological performance of P. tabulaeformis seedlings. Free air temperature increase system of infrared heaters was used to raise monthly average soil and air temperature by 2.6 and 2.1 °C above the ambient. NH4NO3 solution was added for a total equivalent to 25 g N m−2 a−1. Experimental warming and nitrogen addition induced a significant increase in leaf nitrogen concentration, Amax, Φ, antioxidant enzymes activities, ASA and free proline contents, but both of them sharply decreased AOS and MDA level. Interestingly, the interaction of warming and nitrogen fertilization further improved leaf nitrogen concentration, Amax, Φ, and antioxidant compounds accumulation, and also resulted in lower rate of O2− production than either single warming or fertilization. Obviously, the beneficial effects of warming and N fertilization alone on leaf physiology of P. tabulaeformis seedlings were magnified by the combination.