Improving rice population productivity by reducing nitrogen rate and increasing plant density

Area of Science:

• Agronomy
• Plant Physiology
• Agricultural Science

Background:

• Rice tillering potential is significantly influenced by nitrogen level (NL) and transplant density (TD).
• Optimizing the combination of NL and TD is crucial for maximizing grain yield and resource efficiency in rice cultivation.

Purpose of the Study:

• To determine the optimal combination of nitrogen levels and transplant densities for maximizing rice grain yield.
• To investigate the impact of nitrogen and transplant density on tillering potential, leaf biomass, leaf area index (LAI), and canopy photosynthesis potential (CPP).
• To identify strategies for reducing nitrogen fertilizer input while maintaining or increasing rice productivity.

Main Methods:

• Field experiments were conducted using five nitrogen levels (0-360 kg ha-1) and two transplant densities (high density: 32.5x104 hills ha-1; low density: 25.5x104 hills ha-1).
• Data on grain yield, tiller number, leaf biomass fraction, LAI, and CPP were collected and analyzed.
• The study was conducted in Jiangsu, China, from 2012 to 2014.

Main Results:

• Highest grain yield was achieved at high density with 180 kg ha-1 nitrogen and at low density with 270 kg ha-1 nitrogen.
• High transplant density (HD) resulted in more tillers per unit area, higher leaf biomass fraction, larger LAI, and greater canopy photosynthesis potential (CPP).
• At nitrogen levels exceeding 180 kg ha-1, the single-plant tillering ability was 20% higher under low density (LD) compared to HD, indicating a trade-off between planting density and individual plant performance.

Conclusions:

• Adjusting transplant density is an effective strategy to reduce nitrogen fertilizer requirements and improve nitrogen fertilizer use efficiency.
• Increasing planting hills per hectare can substitute for nitrogen supply, with approximately 1000 hills/ha replacing 1 kg N.
• Optimizing transplant density alongside nitrogen management is vital for sustainable agricultural development in rice production.