Sulfur nanoparticle-coated urea improves growth and nitrogen use efficiency in wheat (Triticum aestivum L.) and rice (Oryza sativa L.)
Ahmad Faraz, Asma Imran, Hammad Raza, Muhammad Aamir Iqbal, Asma Rehman
Abstract
Nitrogen (N) is an essential macronutrient required for plant productivity. Urea is a major source of N in global agriculture systems that is lost due to leaching, runoff, and volatilization, inflicting serious productivity, economic, and environmental issues. In contrast, coated urea minimizes N losses by decreasing urease activity and enhances its efficiency by maintaining a continuous N supply for plant uptake and productivity. The present study describes the impact of sulfur nanoparticle (S NP )-coated urea (S NP CU) on the morpho-physiological, biochemical, and yield traits of rice and wheat. Chemically synthesized S NP coated onto urea revealed a fine layer of S NP on urea under a scanning electron microscope. Two varieties each of rice and wheat grown in pots were fertilized as follows: control N/recommended non-coated urea U 100 , three doses of S NP CU (50%, 70%, and 90% of recommended N) in split doses (40% at transplanting, 30% at tillering, and 30% at the panicle stage). Analysis revealed that S NP CU at all doses increased the growth and yield parameters of both crops. The maximum increase was observed in S NP CU 90 , that is, chlorophyll (up to 39%), carotenoids and proteins (up to 20%), sugars and amino acids (up to 60%), along with an increase of at least 5% or more in agronomic efficiency, 10% or more in grain weight, 6% or more in harvest index, and 70% or more in N uptake in both cultivars of wheat and rice. S NP CU 90 increased the nitrogen recovery efficiency by 34% and 26% in wheat varieties Galaxy and FSD-2008, while 36% and 30% in Green Super Rice and 1121 Basmati rice, respectively. S NP CU 90 decreased urease activity up to 37%, 52% on day 2, and 16% and 25% on day 15 in wheat and rice, respectively. This delay increased the duration of N availability in soil for wheat and rice plants, resulting in increased nitrogen use efficiency (NUE) till 15 days. This study has demonstrated that S NP CU minimizes N loss, revealing that even a lower application of S NP CU fulfills the crop N demand. It is concluded that S NP CU at lower rates can be used for large-scale testing in fields for reducing N losses and improving yields.