Regulation of nutrient use efficiency: Boon to wheat cultivar under co-impact of drought and arsenic

Measurement of Nutrient use efficiency (NUE) can be useful for evaluating crops under stressful conditions. The study aimed to elucidate the NUE regulation post-NP (Nitrogen and Phosphorus) supplementation under the combined effect of drought (D) and arsenic (As) stress in wheat seedlings.

Pheno-physiological traits, N-P assimilating enzymes, and nutrient accumulation patterns, along with N-P usage efficiency, were explored to determine the effect of NP under D + As at short (7 days) and long exposures (15 days).

The results showed that dual stress hindered plant growth by interfering with essential metabolic mechanisms and reducing NP acquisition via altered root morphology. Additionally, hampered NP-assimilation was depicted via impaired NO₃⁻ content and NP-assimilating enzymes correlating with increased oxidative damages and reduced NP-accumulation. Concurrently, increased NH₄⁺ content caused toxicity to the plant. NP enrichment improved nutrient content (except for Zn and Cu at 15 days) and growth-related functions via increased NP capture, and assimilatory activity at both exposures. The Glutamate-dehydrogenase (GDH) enzyme appeared as a toxicity cleanser, uplifting assimilation. This further augmented NUE, confirmed by an increment in Physiological Nutrient Use Efficiency (PNUE), Agronomical Nutrient Use Efficiency (ANUE), and Nutrient Recovery Efficiency (NRE). Plants facing drought performed better than those treated with As at 15 days, highlighting the tolerant nature of HD-3237 wheat variety against drought stress, and sensitive nature towards As.

The present findings revealed that N and P have a role in boosting NUE-related mechanisms that enable plants to withstand combined impacts of drought and As stress.