Optimized nitrogen management enhances lodging resistance by modulating stem physicochemical traits in oats

Area of Science:

• Agronomy
• Plant Physiology
• Agricultural Science

Background:

• Oat (Avena sativa L.) is a vital dual-purpose crop, but stem lodging often limits yield, particularly under suboptimal nitrogen (N) management.
• Understanding the specific physicochemical traits influencing lodging under varied N regimes is crucial, especially in high-altitude environments.
• Previous research has not fully quantified the impact of N on stem traits related to lodging resistance.

Purpose of the Study:

• To investigate the quantitative contributions of stem physicochemical traits to lodging resistance in oat under different nitrogen (N) fertilization levels.
• To evaluate the impact of N rates and oat genotype on stem structural components, non-structural carbohydrates, and mineral element accumulation.
• To elucidate the physiological mechanisms underlying oat lodging resistance in a high-altitude agroecosystem.

Main Methods:

• A two-year field trial was conducted on the Qinghai-Tibet Plateau using two oat cultivars (LENA, resistant; QY2, susceptible) across six N rates (0-300 kg·ha⁻¹).
• Stem physicochemical traits, including lignin, cellulose, soluble sugars, starch, and minerals (Ca, K, Si, Mg), were quantified in the second basal internode.
• Statistical analyses, including hierarchical partitioning, structural equation modeling (SEM), and TOPSIS, were employed to identify key determinants of stem strength and lodging index.

Main Results:

• Nitrogen rate, genotype, and their interaction significantly influenced lodging severity and stem physicochemical profiles.
• Increased N application led to higher soluble protein but reduced lignin, cellulose, and key mineral (Si, Ca, K) accumulation.
• Ca, K, Si, soluble sugars, and lignin were identified as primary determinants of lodging index, explaining 87% of the variance. SEM indicated that high N inputs and genotype indirectly increased lodging risk.

Conclusions:

• Optimal nitrogen application rates were determined for lodging-resistant (LENA: 180 kg·hm⁻²) and lodging-prone (QY2: <60 kg·hm⁻²) oat varieties in the Qinghai-Tibet Plateau.
• These findings provide a physiological basis for rational nitrogen management to enhance oat lodging resistance.
• The study offers novel mechanistic insights into oat lodging resistance, crucial for high-altitude agricultural systems.