Physiological and Morphological Responses of Hydroponically Grown Pear Rootstock Under Phosphorus Treatment.

Guodong Chen,Jizhong Wang,Li Wang,Yang Li,Juyou Wu,Cong Jin

doi:10.3389/fpls.2021.696045

Guodong Chen, Jizhong Wang + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2021.696045

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Abstract

Phosphorus (P) is an essential macronutrient for the growth and development of fruit trees, playing an important role in photosynthesis, nucleic acid synthesis, and enzyme activity regulation. The plasticity of plant phenotypic has been investigated in diverse species under conditions of P-deficiency or P-excess. Based on these researches, P level fluctuations in different species result in different characteristics of the response. Nevertheless, little is known about the response of pear seedling rootstock (Pyrus betulifolia Bunge) to the changing of P levels. To explore the effects of different levels of P on the growth of pear seedling rootstock, we performed the hydroponic assays to determine and analyze the biological indexes including growth parameters, photosynthetic rate, root and shoot morphological traits, and concentrations of macro- and micronutrients. The results show that either deficiency or excess of P inhibited the growth and development of pear seedling rootstock. Root growth (down 44.8%), photosynthetic rate (down 59.8%), and acid phosphatase (ACP) activity (down 44.4%) were inhibited under the P-deficiency conditions (0mM), compared with normal P conditions (1mM). On the other hand, dark green leaves, suppression of root elongation (down 18.8%), and photosynthetic rate (down 25%) were observed under regimes of excessive P, compared with normal P conditions (1mM). Furthermore, the root concentration of not only P, but also those of other mineral nutrients were affected by either P treatment. In brief, these results indicated that a careful choice of P fertilizer supply is crucial to ensuring normal growth and development of pear seedling rootstock.

Highlights

Phosphorus is one of the most important nutrients in the growth and development of fruit trees
Excessive P treatment resulted in dark green leaves, with no significant change in leaf expansion rate, stem extension, or root/shoot ratio
An excessive P supply can lead to a dark green leaf color, a dwarf habit, and delayed flowering in crop plants (Maharajan et al, 2018)

Summary

Introduction

Phosphorus is one of the most important nutrients in the growth and development of fruit trees. The use of rootstock in fruit production is inevitable, and rootstocks have a primary role in determining orchard efficiency, they are responsible for water and mineral uptake and provide anchorage for the tree (Guney, 2019; Cimen, 2020; Rufato et al, 2021). Commercial pear trees, such as Asian pear (Pyrus pyrifolia L.), are mainly propagated by grafting. It is of vital significance to study the physiological phenotypic traits and the changes in mineral element concentrations in tissues of birchleaf pear (Pyrus betulifolia Bunge), which is commonly used as the rootstock for commercial pear grafting, under phosphorus stress (deficiency or excess), in order to guide the balanced nutrient application to pear trees, to improve the yield and quality of pear, and to maintain soil fertility and protect the environment

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