Effects of salt and phosphorus fertilization on photosynthesis and nutrient characteristics of Acacia confusa

Abstract

Acacia confusa is an important species in coastal shelter forests. In order to explore the effects of salt and phosphorus fertilization on leaf photosynthesis and nutrient characteristics of the seedlings. NaCl solutions were configured in the concentrations of 0% (B0), 0.2% (B1), 0.4% (B2), 0.6% (B3) and 0.8% (B4), and superphosphate solutions in the concentrations of 0 g·kg-1(P0), 0.5 g·kg-1(P1), and 1.5 g·kg-1(P2). The photosynthesis and nutrient characteristics of the seedlings were determined after being watered by the six combined solutions of salt-phosphorus coupling fertilization. The results were as follows: (1) Salt stress significantly inhibited the growth and development of the seedlings, and the higher the salt content, the greater the effect. Phosphorus application under low-salt stress was unfavorable to the growth of the seedlings, while phosphorus application under medium-high one significantly slowed down the inhibition of the seedling growth. (2) The greater the salt stress, the higher the effects on the photosynthesis of the seedlings. The stomatal closure degree of phosphorus application increased under low and medium salt stress, which aggravated the effect of salt stress on photosynthesis of the seedlings. Appropriate phosphorus application under high-salt stress could significantly improve the photosynthetic capacity of the seedlings. (3) Salt stress significantly reduced chlorophyll content and caused harm to photosystem II. Phosphorus fertilization on the seedlings under low-salt stress had adverse effects on chlorophyll synthesis. Appropriate fertilization of phosphorus in high-salt stress could increase chlorophyll synthesis, stabilize cell membrane structure, and improve the potential photosynthetic capacity of leaves. (4) Salt stress had strong interference on the contents of Fe, Mn, Na, Cu and other metal elements in leaves. Phosphorus application under salt stress could effectively promote the absorption of some elements by seedlings. In conclusion, phosphorus application after salt stress can improve the photosynthesis and nutrient absorption ability of A. confusa seedlings on the whole. The results provides a theoretical basis for improving the salt tolerance and phosphorus utilization rate of A. confusa, and have guiding significance for the sustainable management of coastal shelter forests.

Keywords

• salt stress
• phosphorus fertilization
• photosynthesis
• nutrient content
• acacia confusa seedlings