Ozone Tolerant Rice for Bangladesh: From Molecular Understanding of Tolerance Mechanisms to Field Application

• Applicant: Professor Dr. Michael Frei
• Subject Area: Plant Cultivation, Plant Nutrition, Agricultural Technology ; Plant Breeding and Plant Pathology
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426004147

• Final Report Year: 2024

Final Report Abstract

Ozone is an air pollutant in the troposphere and impairs the growth and yield of crops. In Bangladesh, the ozone problem is particularly serious due to the high population density, the economic development and the favorable climate for ozone formation. However, little is known about the effects of ozone stress on rice production in Bangladesh, although widespread rice varieties from Bangladesh were very sensitive to ozone in previous fumigation trials. The objectives of this study were therefore (i) to assess the importance of ozone stress for rice production in Bangladesh and (ii) to develop ozone tolerant rice varieties for Bangladesh. To achieve the first objective, field trials were conducted at four locations in Bangladesh over three cultivation periods, in each of which 20 rice varieties were grown with or without treatment with the chemical ethylenediurea (EDU). EDU is sprayed regularly on the leaves and specifically protects the plants from ozone stress. Ozone concentrations at the experimental sites were between 53 and 84 ppb on a daily average and thus clearly in the plant-damaging range. The application of EDU increased rice yields by an average of 10.4%, indicating that plants without EDU protection were under ozone stress. However, there were also major differences between the varieties used. For example, the landrace Kasalath did not react to EDU at all, which indicates a high level of ozone tolerance. To counter the ozone problem, ozone-tolerant rice lines were developed in the second part of the project. The ozone-tolerant landrace Kasalath was crossed with the ozone-sensitive high-yielding varieties BRRI dhan28 and Binadhan11 from Bangladesh in order to transfer the ozone-tolerant loci OzT8 and OzT9 by means of marker-assisted backcrossing. For this purpose, two backcrossing steps were carried out and lines were then further developed up to the BC2F3 generation. A total of 79 of these lines were then screened for ozone tolerance in a fumigation trial and further selected on the basis of agronomically favorable morphology. For a final ozone fumigation trial, 19 BC2F4 lines were selected and comprehensively characterized for their ozone tolerance in a further fumigation trial. Newly developed crossing lines showed improved physiological traits under ozone stress compared to the sensitive parent varieties (e.g. fewer leaf symptoms, improved chlorophyll:carotenoid ratio, increased photosynthetic efficiency). The grain yield loss in the parental lines was 30 to 40 percent, while it was significantly lower in the newly developed crossing lines, as some lines showed no significant yield loss at all. The project illustrates the impact of ozone pollution on food security in Bangladesh and contributes to adaptation to the prevailing atmospheric conditions by developing new rice varieties.

Publications

• Adapting cereal crops to elevated tropospheric ozone. Invited seminar talk, Bangabanhu Sheik Mu-jubur Rahmen Agricultural University, Kaliganj, Bangladesh, 13th January 2020.
  Frei M.
  
• Adapting cereal crops to elevated tropospheric ozone. Invited seminar talk, Bangladesh Institute of Nuclear Agriculture, Mymensingh, Bangladesh, 13th January 2020.
  Frei M.
  
• Adapting rice to abiotic stresses. Invited seminar talk, International Rice Research Institute (IRRI), Los Banos, The Philippines 4th October 2022.
  Frei M. & Pandey A.
  
• Interactive effects of tropospheric ozone and blast disease (Magnaporthe oryzae) on different rice genotypes. Environmental Science and Pollution Research, 29(32), 48893-48907.
  Alam, Muhammad Shahedul; Maina, Angeline Wanjiku; Feng, Yanru; Wu, Lin-Bo & Frei, Michael
  
• Genetic variation in ozone tolerance of cereal crops and its application in plant breeding. Invited seminar talk, Sino-German Workshop on Adapting Crop Production to Air Pollution and Climate Change, Gießen, Germany, 23rd August 2023.
  Frei M.
  
• Evidence for tropospheric ozone effects on rice production in Bangladesh. Science of The Total Environment, 909, 168560.
  Frei, Michael; Ashrafuzzaman, Md; Piepho, Hans-Peter; Herzog, Eva; Begum, Shamsun Nahar & Islam, Mirza Mofazzal