Effects of exogenous zinc on the physiological characteristics and enzyme activities of Passiflora edulis Sims f . edulis seedlings

PeerJ. 2023 Oct 18:11:e16280. doi: 10.7717/peerj.16280. eCollection 2023.

Abstract

Passionflower (Passiflora edulis Sims) is widely distributed in tropical and subtropical areas for edible, medicinal and skin care product processing, and the market demand is large. Zinc (Zn) is a necessary trace element for plant growth and development. In many countries, the content of Zn in soil is low and/or bioavailability is low. The exogenous application of Zn has become a common agronomic measure in agriculture. However, the effect of Zn on the physiological characteristics and enzyme activity of passionflower seedlings is not clear. In this study, pot experiments were conducted to analyse the effects of different concentrations of Zn (0, 200, 400, 800 mg kg-1) on the plant growth, photosynthetic pigments, osmotic regulators, membrane system and antioxidant enzyme system of purple passionflower (Passiflora edulis Sims f. edulis) seedlings, and Pearson correlation and principal component analyses were performed. The results showed that (1) the 200 mg kg-1 Zn treatment increased the contents of chlorophyll a (37.65%), chlorophyll b (41.22%), chlorophyll a+b (38.59%) and carotenoids (29.74%). The value of chlorophyll a/b changed little and had no effect on leaf growth. (2) The contents of proline (Pro) and malondialdehyde (MDA) in P. edulis Sims f. edulis seedlings treated with 400 mg kg-1 Zn increased significantly by 116.84% and 42.69%, respectively. The activities of catalase (CAT) and peroxidase (POD) increased by 16.82% and 18.70%, respectively. Superoxide dismutase (SOD), leaf area (LA), leaf perimeter (LP) and leaf width (LW) decreased significantly by 47.20%, 19.75%, 8.32% and 11.97%, respectively. (3) 800 mg kg-1 Zn significantly increased the contents of Pro (202.56%) and MDA (26.7%) and the activities of CAT (16.00%) and POD (67.00%), while the soluble sugar (SS), SOD, LA, LP and LW decreased significantly by 36.67%, 32.86%, 23.36%, 8.32% and 11.18%, respectively. (4) There was a significant positive correlation between Pro and photosynthetic pigments and between SOD and leaf growth and a significant negative correlation between POD and SS and between SOD and MDA. (5) A low concentration (200 mg kg-1) of Zn promoted the growth of P. edulis Sims f. edulis seedlings and allowed stress caused by high Zn concentrations to be tolerated. The results of this study can provide a reference for the application of Zn fertilizer to P. edulis Sims f. edulis.

Keywords: Antioxidant enzymes; Malondialdehyde; Osmotic regulation; Passiflora edulis Sims; Photosynthetic pigment; Zinc (Zn).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbohydrates / pharmacology
  • Chlorophyll A / pharmacology
  • Passiflora*
  • Peroxidase / pharmacology
  • Seedlings
  • Superoxide Dismutase / pharmacology
  • Zinc* / pharmacology

Substances

  • Zinc
  • Chlorophyll A
  • Superoxide Dismutase
  • Peroxidase
  • Carbohydrates

Grants and funding

This work is supported by the Guizhou Science and Technology Support Program (NO. QKHZC (2020) 1Y176, NO. QKHZC (2021) General 460) and the National Key R & D Program of China (2021YFD1100303). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.