Understanding and reducing lodging in maize and rice.

Severe weather can cause crops to become uprooted or their stems to break, a process called lodging. This means that the crops do not grow to their full potential which reduces the quantity of seed they produce (the yield). Lodging makes crops more susceptible to infection by fungi which can produce toxic chemicals known as mycotoxins which render the grain unusable. These impacts of lodging substantially reduce the value of a crop and there can be additional costs of drying the grain. By taking appropriate action (e.g. choice of crop variety and how it is managed) it is possible for farmers to reduce the likelihood of lodging. Over the past 20 years great advances have been made with improving understanding and control of lodging in cereal crops (e.g. wheat) grown in the UK through the development of realistic models of the lodging process which have been used to develop practical husbandry strategies enabling farmers to reduce lodging. Understanding of the lodging process in maize and rice is less advanced than in UK cereal crops and lodging in maize and rice crops commonly reduces yields by up to 40% representing a major constraint for crop productivity, particularly for low/middle income countries.

This project will use world leading UK expertise in lodging science to develop understanding and mitigation strategies that enable maize and rice producing regions to minimise lodging. This strategy will increase the resilience of maize and rice production systems to climate variability and produce safer food by reducing mycotoxin development in lodged crops. Both rice and maize have very different morphologies from the crops that have already been modelled for the lodging process. New lodging models will be developed that take account of the large hanging panicles, high tiller numbers and shallow rooting system of rice; and the thick hollow stem, braced root system, much taller stature and large leaves of maize. Additionally characteristics of the climate (wind and rainfall) of different regions will be built into the models. These lodging models will be developed and tested using wind tunnel tests on pot grown plants and field tests.

A framework for identifying regions and fields with the highest risk of lodging will be produced which will account for how landscape features affect wind flow over crops and how Earth Observation (EO) technologies (e.g. vegetation index maps from satellites) may be used to identify the fields with crops that are most at risk to lodging. Frequently it is found that crops with large canopies (vegetation indices) have a greater risk to lodging later in the growing season. The understanding about wind flow, EO technologies and the new lodging models will be combined into a single integrated system. This system will then be used to help farmers to mitigate lodging risk; 1) strategically by planting lodging resistant varieties in regions with a high risk of lodging and 2) tactically by reducing nitrogen fertiliser and prioritising harvest for fields (and even part fields) which are shown to have developed a high risk of lodging during the growing season. The lodging models will be used to understand how variation in crop parameters caused by changes in crop husbandry, environmental parameters (wind, rainfall and soil type) and predictions of climate change will affect lodging risk in maize and rice within different global regions. This work will identify which crop parameters have the greatest influence on lodging risk and therefore should be targeted by plant breeders.

Lodging (flattening of crops by adverse weather) in maize and rice severely constrains crop productivity in many developed and developing countries. Lodging causes yield losses of up to 40% in rice and maize, reduces grain quality, increases time to harvest, increases grain drying costs and increases health damaging mycotoxins on grain. It is estimated that lodging in rice and maize reduces crop production in China and Mexico by $1500 Million per year. The UK has the world leading lodging scientists and facilities, which have been used very effectively to reduce lodging of cereals in the UK. However, understanding of the lodging process in maize and rice is far less advanced.

This project will carry out novel research to improve understanding of the lodging process for maize and rice grown in LMICs in Asia and Central/S America, develop new and fruitful multi-disciplinary collaborations between UK scientists and LMIC scientists and provide training for LMIC scientists. In order to achieve this we will undertake laboratory and field investigations to develop and test models describing the lodging process for maize and rice. We will use these models within a broader analytical framework which incorporates simulations of wind flow over topography and crop growth information derived from satellite data in order to develop a system capable of identifying regions, fields and part fields with the highest risk of lodging. This system will then be applied to support strategic and tactical agronomic decision making and to determine the effects crop husbandry, environment and climate change on lodging risk in different global regions which will define priority traits for plant breeding programmes. Importantly, the project will deliver a knowledge exchange programme to develop collaborations with and offer training to LMIC scientists and convey the outputs of the project to a wide range of farmers, agronomists, agribusinesses, plant breeders and extension workers in LMICs.

This project will provide the foundation research capability for researchers and practitioners in LMICs to develop germplasm and crop husbandry systems for minimising lodging in maize and rice. This project will benefit farmers, plant breeders, extension workers, the broader agricultural industry, consumers and the environment of LMICs.

The understanding about the lodging process of rice and maize developed within this project will identify the priority traits that maize and rice breeders should focus on to produce new varieties with greater resistance to lodging. Project partner CIMMYT breed new varieties of maize for a wide range of global regions and will be particularly well placed to exploit this information.

The outputs from this project will allow maize and rice farmers of LMICs to make informed decisions about the strategies and techniques they can use to reduce weather-induced lodging damage to crops. It will provide the foundation for identifying which fields are susceptible to lodging and thereby which crop husbandry strategy (e.g. crop variety, seeding rate) is optimal. This will produce financial benefits for farmers by reducing yield loss, diminished grain quality, prevalence of mycotoxins and cost of drying grain.

The project will also support farmers to make effective tactical decisions within the growing season to minimise lodging by controlling crop growth (e.g. by varying fertiliser and using plant growth regulator treatments). The project will provide the underlying principles for developing the technologies to optimise these agronomic practices across the farm, for individual fields and within fields. This will have direct financial benefits for farmers by minimising yield losses due to lodging while also minimising spend on chemical applications. Achieving greater yield per unit of input costs will help farmers to withstand the high volatility in global prices of maize and rice. Reducing production costs will also help to generate positive outcomes for consumers in terms of food price and availability. Better targeting of crop inputs will reduce environmental pollution, e.g. reducing nitrogen fertiliser to areas of crop with high nitrogen content will help to reduce excess nitrogen use, risk of nitrate leaching and nitrous oxide emissions.

Initial benefits will be achieved in China and Mexico where some of the research activities will be carried out by project partners CIMMYT and China Agricultural University. Three international workshops, training programmes, agricultural extension activities and media publications will disseminate the objectives and outcomes of the project widely to farmers, plant breeders and agronomists. This will ensure that the new understanding developed in this project is adopted widely throughout LMICs. Furthermore, the project will benefit the other LMICs that grow maize and rice including; Colombia, Venezuela, Peru, Ecuador, Bolivia and several Central American countries where CIMMYT carry out extension activities. Lodging control extension specialists from the UK (ADAS UK Ltd) will help to ensure impact is achieved. The research outcomes will present opportunities for plant breeding, precision farming, and agro-chemical companies to develop new or improved products targeted at reducing lodging.

Therefore, by improving the resilience of maize and rice production systems against lodging caused by extreme weather events, this project will make substantial contributions towards improving the economies of LMICs, bolstering innovation in the agricultural industry, reducing the environmental impacts of agriculture and ultimately securing affordable food supplies.