A practical, rapid generation-advancement system for rice breeding using simplified biotron breeding system.

Area of Science:

• Plant Breeding
• Agricultural Science
• Genetics

Background:

• Traditional rice breeding is time-consuming.
• The biotron breeding system (BBS) accelerates generation advancement but involves labor-intensive steps like tiller removal and embryo rescue.
• These manual processes limit the scalability of BBS for large populations.

Purpose of the Study:

• To investigate the impact of environmental factors on rice growth and development in controlled environments.
• To develop a simplified biotron breeding system (sBBS) that is more practical for large-scale rice breeding.
• To reduce the time required for rice generation advancement.

Main Methods:

• Investigated the effects of elevated CO2 concentration, tiller removal, and root restriction on days to heading (DTH) in rice within growth chambers.
• Proposed and implemented a simplified BBS (sBBS) by controlling CO2 levels, day-length, and root volume, while omitting tiller removal and embryo rescue.
• Utilized the sBBS to develop isogenic lines by performing four crossing cycles within a year.

Main Results:

• Increased CO2 concentration significantly decreased DTH.
• Tiller removal and root restriction had minimal impact on DTH but drastically reduced seed yield.
• The sBBS successfully reduced the generation interval in rice ('Nipponbare') to less than 3 months.
• Four crossing cycles were completed annually using the sBBS for isogenic line development.

Conclusions:

• The sBBS offers a practical and efficient method for accelerating rice generation advancement.
• Optimizing CO2 levels and day-length, alongside appropriate root volume management, is key to the sBBS.
• The simplified system eliminates laborious manual interventions, making rapid breeding cycles feasible.