Co-applied Nitrogen and Auxin via Nano-clay-Polymer Composites Enhances Yield and Nitrogen Use Efficiency

Simultaneous application of nitrate (NO 3 − -N) and synthetic auxin in nano-clay-polymer composites (NCPC) is hypothesized to increase rice yield and nitrogen (N) use efficiency. A pot experiment was conducted in 2019 at ICAR-National Rice Research Institute (NRRI), Cuttack, Odisha, India, during Rabi season with rice variety Sahbhagi dhan with eight treatments, viz. control, auxin 1-naphthaleneacetic acid (NAA), sodium nitrate (NaNO 3 ), NAA + NaNO 3 , NCPC, NCPC + NAA, NCPC + NaNO 3 and NCPC + NAA + NaNO 3 , in four replicates using a basal addition of ^1/ _3. of the recommended dose, i.e. 35.71 mg N kg −1 . Except for the control, urea was applied to all the treatments at maximum tillering and panicle initiation stages using one-third of the recommended N dose at each stage without further addition of NAA or NCPC. Phosphorus and potassium were added at the rate of 17.86 mg kg −1 in all pots (including control). Plant yield increased more in NCPC-loaded NaNO 3 fertilizer treatments than the NaNO 3 fertilizers alone. Combined application of NaNO 3 and NAA loaded in NCPC resulted in the highest yield, which was 71