Silicon Application Induced Alleviation of Aluminum Toxicity in Xaraés Palisadegrass

Guilherme Baggio,Marcelo Rinaldi Da Silva,Marcelo Carvalho Minhoto Teixeira Filho,Caio Augusto Tritapepe,Fernando Shintate Galindo,Arshad Jalal,Elisângela Dupas,Nathália Cristina Marchiori Pereira,Marcio Mahmoud Megda,Monique Oliveira Luchetta

doi:10.3390/agronomy11101938

Abstract

Aluminum (Al) toxicity is a major abiotic constraint for agricultural production in acidic soils that needs a sustainable solution to deal with plant tolerance. Silicon (Si) plays important roles in alleviating the harmful effects of Al in plants. The genus Urochloa includes most important grasses and hybrids, and it is currently used as pastures in the tropical regions. Xaraés palisadegrass (Urochloa brizantha cv. Xaraés) is a forage that is relatively tolerant to Al toxicity under field-grown conditions, which might be explained by the great uptake and accumulation of Si. However, studies are needed to access the benefits of Si application to alleviate Al toxicity on Xaraés palisadegrass nutritional status, production, and chemical–bromatological composition. The study was conducted under greenhouse conditions with the effect of five Si concentrations evaluated (0, 0.3, 0.6, 1.2, and 2.4 mM) as well as with nutrient solutions containing 1 mM Al in two sampling dates (two forage cuts). The following evaluations were performed: number of tillers and leaves, shoot biomass, N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, Zn, Al, and Si concentration in leaf tissue, Al and Si concentration in root tissue, neutral detergent fiber (NDF), and acid detergent fiber (ADF) content in Xaraés palisadegrass shoot. Silicon supply affected the relation between Si and Al uptake by increasing root Al concentration in detriment to Al transport to the leaves, thereby alleviating Al toxicity in Xaraés palisadegrass. The concentrations between 1.4 and 1.6 mM Si in solution decreased roots to shoots Al translocation by 259% (from 3.26 to 1.26%), which contributed to a higher number of leaves per plot and led to a greater shoot dry mass without affecting tillering. Xaraés palisadegrass could be considered one of the greatest Si accumulator plants with Si content in leaves above 4.7% of dry mass. In addition, Si supply may benefit nutrient-use efficiency with enhanced plant growth and without compromising the chemical–bromatological content of Xaraés palisadegrass.

Highlights

Brazil has about 180 million hectares of pastures and is one of the largest commercial cattle producers of the world, which depend on pastures as a main feed source [1], since they are less costly than other forms of feed [2]
Leaf Si concentration responded linearly to the increasing Si concentrations (Figure 2A), while leaf Al concentration showed a non-linear response to Si concentrations (Pmin [lowest estimated value] = 1.6 mM Si) (Figure 2C)
We verified that the increasing Si uptake in Xaraés palisadegrass leaves had directly affected the modulation of Si/Al uptake by decreasing leaf Al concentration as mediated with Si supply

Summary

Introduction

Brazil has about 180 million hectares of pastures and is one of the largest commercial cattle producers of the world, which depend on pastures as a main feed source [1], since they are less costly than other forms of feed [2]. Of Brazil’s total agricultural land; it is estimated that 80% of these pastures are established in degraded soils [3,4]. Tropical fodder grows in low-fertility acidic soils [5]. Aluminum (Al) toxicity is represented as one of the main yield-limiting factors for crops and pastures in acidic soils [6]. This element is one of the most dominant minerals in the earth’s crust, representing about 8% of its mass [7]. Acidic soils constitute ≈ 30% of the world’s total land area and 50% of the potentially available arable land worldwide [8]

Methods

Results

Discussion

Conclusion