Plant Growth Chambers for Rice Research

Rice (Oryza sativa) is a staple food crop providing calories and nutrition for more than 50% of the world’s population ⁽¹⁾ It is a semi-aquatic cereal belonging to the grass family and is grown primarily in Asia and South-east Asia with some production occurring in Brazil and the United States ⁽²⁾. The increasing frequency of abiotic stresses such as high or low temperatures, drought, flooding and potential high salt and iron concentrations in the soil is reducing rice security ^(3,4,5,6). These changing and fluctuating climactic conditions can also promote the growth of pests and diseases. It is estimated that rice yields will decrease by 3.2 % per degree Celsius temperature increase and this will result in an overall 15-35% global decrease in yield ⁽⁷⁾. Rice grain quality deterioration is also predicted to increase to 85% due to climate pressures ⁽⁸⁾.

Common Research

Rice research often focuses on improving crop yield, understanding environmental impacts, and addressing and improving challenges in cultivation. Here are some common research areas:

• Climate Change: Simulating different climate scenarios to assess rice's resilience to drought, heat, and other stresses.
• Genetics and Breeding: Studying the effects of specific genes or genetic modifications on rice growth and yield.
• Disease and Pest Resistance: Screening rice varieties for resistance to diseases and pests under controlled conditions.
• Nutrient Uptake: Investigating the effects of different nutrient levels on rice growth and development.
• Optimizing Growth Conditions: Identifying optimal conditions for rice growth and yield in specific environments.

Recent Developments:

• Speed Breeding: As the population continues to grow it is estimated that cereal crop yields need to double by 2050 with rice yields needing to increase by 2.4% per year ⁽⁹⁾. Due to the importance of rice as a major food crop and the increased probability of decreased yields and quality, heat and drought stress tolerance and resilience are being examined through breeding and cultivation practices programs. A new speed breeding protocol known as “SpeedFlower” has been developed that allows 4-5 generations per year to be grown in plant growth chambers with a 50% reduction in seed maturation time ^(10,11). The SpeedFlower breeding technique uses an optimized spectrum, intensity, photoperiod, temperature, relative humidity, fertigation and hormonal regulation ^(10,11).

• Indoor rice farming: The feasibility to grow rice in protected environments such as greenhouses or vertical farms has been evaluated and is now ready to move from bench to scale ^(12,13,14). The critical daily mean temperature requirements for each developmental stage have been published with the caveat that these are variety specific (Table 1) ⁽¹³⁾.

Table 1

• Lighting: Whether growing rice in controlled environment research chambers or a vertical farm, lighting is central to bring this crop right through its growth cycle to grain filling and harvest. It has been reported that the optimal light conditions for rice grown in plant factories with artificial lighting (PFALs) are PPFDs of 1000 umol/m²/s and a 12 h photoperiod which realizes a Daily Light Integral (DLI) of 43 mol/m²/day. The day temperatures were kept at a constant 27 °C, the night temperatures were 23°C, the relative humidity was 70% and the CO₂ was set to 400 ppm ⁽¹⁴⁾. These conditions resulted in rice yields that were 40-60% greater than the average paddy field yields in Japan⁽¹⁴⁾.

Recommended Plant Growth Chambers

Both reach-in and walk-in plant growth chambers are suitable for rice research. Reach-in chambers are suitable for smaller experiments and research on individual plants or small populations. Medium to large walk-in chambers can accommodate larger plant populations and more complex experiments.

Conviron offers a range of controlled environments suitable for rice research. Reach-in chambers that are single tier and high-light like the GEN1000 TA and GEN2000 TA and walk-in rooms like the GR, the BDW and EVO series, are designed to provide precise control over temperature, light, and humidity levels. These chambers are versatile and can accommodate the specific needs of rice cultivation and stress biology research. Airflow recommendations would vary based on the type of container researchers are using for growing (pots, trays, large flooded trays, etc.). Options suitable for rice research include automatic watering and CO₂ enrichment. Growth chamber and room alternatives include:

• BDW
• Conviron Growth House^TM
• EVO
• GEN1000-TA
• GEN2000-TA
• GR
• MTPS - 1 Tier
• PGR
• PGW