Effects of Phosphorus Supply on Root Morphology and Phosphorus Uptake in Maize Seedlings under Different Water Regimes

Xinying Chen,Yanjun Gao,Lingjun Hong,Hongliang Tang

doi:10.11648/j.ajaf.20200801.14

Abstract

Water deficit and phosphorus (P) deficiency in soil have become the main limiting factors for the production of maize (Zea mays L.), but it still remains unclear how water and P regulate maize root morphology and P uptake. Through an experiment of potted soil culture, this study has set 4 water gradients [35% (W1), 55% (W2), 75% (W3) and 100% (W4)] of field capacity, and two P levels [high P: 205 mg (P)∙kg-1; low P: 11 mg (P)∙kg-1] to investigate the coupling effects of water and P on root growth and P uptake in maize seedlings. The results have shown that: (1) Regardless of soil P supply, the shoot dry weight, root dry weight, total root length, and root surface area of maize seedlings shows a trend of increasing first and then decreasing with increasing water supply intensity; the soil available P content also shows similar trend; the root mass ratio and mean root diameter shows a downward trend with the increase of water supply intensity; furthermore, the P content and P accumulation of plants shows a steady increase with the increase of water supply intensity; (2) Water deficit (W1) and excess water supply (W4) is not conducive to root growth and dry matter accumulation in maize. Water deficit (W1) inhibits the acquisition of soil P by maize, while excess water supply (W4) causes extravagant absorption of soil P (W4). Mild water stress (W2) can promote the growth and dry matter accumulation of maize roots and reduce the extravagant absorption of soil P, and adequate water supply (W3) can promote root growth, dry matter accumulation and the absorption of soil P; (3) Phosphorus supply significantly increases the dry weight, root dry weight (except W4), total root length, root surface area, plant P content (except W4) and P accumulation of maize seedlings, but reduces the root mass ratio of maize. It is thus evident that water is a key factor controlling the morphology and accumulation of dry matter in maize roots, and P is a key factor controlling P uptake and soil available P content in corn field. The better coupling between water and P can promote maize root growth and dry matter accumulation, as well as reduce the extravagant absorption of soil P.

Highlights

As one of the most important nutrient factors, phosphorus is involved in the regulation of many physiological and biochemical reactions in plants and plays a crucial role in plant growth and development [1]
In the later stages of water deficit (W1 moisture treatment) and low phosphorus stress (Figure 1b; Figure 2a, b), the root dry weight, total root length, and root surface area of maize demonstrate a significant decrease, while the root mass ratio exhibits a marked increase (Figure 1c), which is consistent with the results reached by Hermans et al [17] and Songsri et al [18]
Jin et al [12] carried out field trials of two soybean varieties and found out that: under the condition of severe water stress (65%~75% of field capacity), phosphorus supply substantially increased the total root length and root surface area of 'Denglong 46', but its increase in 'Heisheng101' was small; under the condition of adequate water supply (65%~75% of field capacity), the phosphorus supply markedly increased the total root length and root surface area of the two soybean varieties, indicating that soil moisture status can regulate the response of different soybean genotypes to phosphorus supply

Summary

Introduction

As one of the most important nutrient factors, phosphorus is involved in the regulation of many physiological and biochemical reactions in plants and plays a crucial role in plant growth and development [1]. Adsorption, complexation, and bioconversion, the bioavailability of phosphorus is low [2]. In order to obtain insoluble phosphorus in soil, plants increase the bioavailability of soil phosphorus by increasing root growth, branching and strengthening rhizosphere effects [3,4,5]. When the plant absorbs enough phosphorus to have a proper level of phosphorus on the ground, the roots’ proliferative response and ability of phosphorus absorption tend to be smaller [6, 7]. Moisture affects the transport of phosphorus nutrients in soil and the absorption, utilization, and distribution of phosphorus by plants.

Methods

Results

Conclusion