How do crop varieties developed through different breeding methods perform in field in terms of yield and biotic and abiotic stress? A systematic map protocol.

Background: Despite Nepal's considerable progress towards sustainable development goals in recent years, much more needs to be done to address the key development challenges. Agriculture plays an indispensable role in Nepal's development trajectory, but Nepal faces complex challenges in its agricultural landscape. Addressing these challenges requires a coordinated effort and the use of robust scientific evidence to support decision making - knowledge on effectiveness of crop varieties will help to direct support and resources where they are needed most. Despite heavy investment in seed technology, benefits to crop productivity and farmer income have been limited. Changing weather patterns and an overreliance on imported crops have led to a potentially fragile system. There is therefore a need for an overview of what research is being invested in, along with information about the effectiveness of new crop varieties, including imports. Methods: This systematic map will collate the literature from Nepal and its neighbouring countries to answer the question: "How do crop varieties developed through different breeding methods perform in field in terms of yield and biotic and abiotic stress?". We will search for evidence across a suite of bibliographic databases and grey literature resources using a tried-and-tested search strategy. Potentially relevant records will be screened against a set of a priori, explicit eligibility criteria, ensuring consistency in application prior to use. Relevant records will proceed to meta-data extraction and coding, followed by visualisation and narrative description of the evidence base as a whole. Knowledge gaps and clusters will be identified across pairs of variables including crop, breeding method, country and measurement methods to assess the volume and quality of evidence across the evidence base. This process will highlight areas where further research is needed, along with topics for which sufficient evidence exists to allow full synthesis of study findings in answer to questions regarding the effectiveness of different plant breeding methods in terms of yield and stress tolerance.