Effect of the Rare Earth Element Lanthanum (La) on the Growth and Development of Citrus Rootstock Seedlings.

Hang Yin,Changpin Chun,Junxiu Wang,Yizhong He,Yao Zeng,Lili Ling,Li Cao,Xingzheng Fu,Liangzhi Peng,Xinjian Shen

doi:10.3390/plants10071388

Hang Yin, Changpin Chun + Show 8 more

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https://doi.org/10.3390/plants10071388

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Abstract

Rare earth elements (REEs) can affect the growth and development of plants. However, few studies have been carried out on the effects of REEs on citrus seedlings. In this study, the growth parameters, toxicity symptoms, chlorophyll content, and La content of three citrus rootstocks are analyzed under different concentrations of La, a representative REE. The results show that the growth of citrus rootstock seedlings was stimulated at La ≤ 0.5 mmol·L−1 and inhibited at concentrations above 1 mmol·L−1. The chlorophyll and carotenoid contents of trifoliate orange (Poncirus trifoliata L. Raf.) and Ziyang Xiangcheng (C. junos Sieb. ex Tanaka) leaves of plants grown at low concentrations of La (≤1.5 mmol·L−1) were similar to those of the control but were significantly reduced at 4 mmol·L−1 La. Toxic symptoms gradually appeared with increasing La concentrations, with yellowed leaves and burst veins appearing at 4 mmol·L−1 La. The symptoms of toxicity were most severe in trifoliate orange, followed by Shatian Pomelo (Citrus grandis var. shatinyu Hort) and then Ziyang Xiangcheng. Moreover, in leaves, the Ca content was significantly negatively correlated with La content (p < 0.01). These results indicate that La has a hormesis effect on the growth of citrus rootstocks. Of the studied citrus seedlings, Ziyang Xiangcheng is the most resistant to La.

Highlights

Rare earth elements (REEs) are a homogenous group of 17 chemical elements in the periodic table, and their increasing use in industrial and agricultural practices has resulted in REEs being widely studied in recent years to better understand their environmental effects [1]
The growth parameters of the three citrus rootstocks differed according to the different La treatments used (Figure 1)
Many studies have shown the promotion of plant growth and development occurs under low concentrations thatofthe promotion plant growth occurs under concentrations of

Summary

Introduction

Rare earth elements (REEs) are a homogenous group of 17 chemical elements in the periodic table, and their increasing use in industrial and agricultural practices has resulted in REEs being widely studied in recent years to better understand their environmental effects [1]. Increasing the level of REEs in the soil directly affects the growth and development of plants [2,3]. Numerous studies have revealed that REEs have a hormesis effect on the growth and development of plants [4,5,6,7]. An appropriate amount of REEs is beneficial to plants, promoting plant growth and development as well as improving their photosynthetic capacity. High concentrations of REEs may have toxic effects on plants, mainly leading to the slowing of growth, wilting and yellowing leaves, and weakening, as measured by other physiological and biochemical indicators [4,5]. Low doses of REEs may improve the structural stability of the plasma membrane [8,9], while high doses of REEs may cause changes in the membrane protein structure and increase membrane permeability [10]

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