Foliar Application of Innovative Sources of Silicon in Soybean, Cotton, and Maize

Abstract

This study aimed to determine the effect of foliar (Si) spraying of silicon using different sources on leaf Si concentration, photosynthetic parameters, and yield in soybean, cotton, and maize. Three experiments were carried out in the 2016/2017 growing season (Study 1), and three experiments were carried out in the 2017/2018 season (Study 2). Study 1 was arranged using a randomized block design in a 4 × 4 factorial scheme consisting of four sources of Si: sorbitol-stabilized sodium and potassium silicate (SiAl), PEG-400-stabilized monosilicic acid (SiAc), nanosilica (Nano), and potassium silicate without stabilizers (SiK), and four silicon concentrations: (0.0, 0.25, 0.50, and 1.0 g L−1), with three replicates. Study 2 was arranged in a randomized block design consisting of a treatment without Si (0 g L−1) and treatments with three sprayings of SiK (0.6 g L−1) or SiAl (0.6 g L−1), with seven replicates. In Study 1, all Si sources studied increased the leaf Si concentration. In addition, increasing Si concentrations also increased the photosynthetic variables and yield of soybean, maize, and cotton plants, with SiAl at the concentrations of 0.5 and 1.0 g L−1 being superior to the other sources, promoting greater yield. In Study 2, SiAl and SiK increased the leaf Si concentration, photosynthetic variables, and yield in soybeans, cotton, and maize plants. It is concluded that stabilized potassium silicate can be used as a new option in relation to the conventional source, potassium silicate for fertilization in annual crops. Our study proposes the use of this Si source for foliar spraying at a concentration between 0.6 and 0.8 g L−1 for soybean, cotton, and maize crops, especially when the leaf Si contents are below 2.0, 5.5, and 26.6 g kg−1, respectively.