Oats have been grown in Ireland since the Bronze age and once occupied a land area of over 1.5 million acres when oats were the primary feed for horses. The acreage of oats fell as horses were replaced with vehicles, but there is now renewed interest in oats as a result of a new appreciation of the health benefits of oat grains. Oat grains have been shown to have cholesterol, insulin, and glucose-lowering effects, reducing the risk of diabetes and heart disease. Oats are now classified as a functional food (foods with health-giving properties).
Lodging in Oats
In many respects, oats are similar to other cereals to grow. However, compared to other cereals, such as barley and wheat, oat crops have a greater tendency to lodge compared to other cereals. The stems of cereal plant should be upright for proper functioning. Lodging occurs when stems are permanently displaced from their vertical position as a result of wind and precipitation and can occur anytime from when the head (plant part which contains the grains) of the oat plant emerges until harvest. Root lodging occurs when the roots of the oat plant are no longer able to keep the plant upright when the soil becomes too wet. Stem lodging occurs when the lower part of the stem buckles or bends. Lodging is a frequent phenomenon in oats and can cause significant yield losses particularly if lodging occurs soon after panicle emergence. In addition to yield losses, lodging can also lead to a reduction in grain quality and increased harvesting and drying costs.
In spite of the prevalence of lodging in oat crops, relatively little research has been undertaken to understand this process in oats and improve lodging resistance. The resistance of a crop to lodging is influenced by a number of agronomic factors, including choice of variety, sowing date, seeding rate, the timing and rate of nitrogen fertilization, and the use of growth regulators. However, there is a poor quantitative understanding of how these factors can be combined to improve the lodging characteristics of oat plants. Furthermore, the reasons why oats are more susceptible to lodging compared to other cereal crops are not fully understood.
The lack of understanding of the lodging process in oats is partly attributable to the complex nature of the process, which requires a knowledge of several disciplines for a complete understanding. Key disciplines required to understand lodging include agronomy, physiology, wind engineering, and modeling. However, a multidiscipline team from Teagasc, ADAS, and the University of Birmingham with expertise in each of these areas has now been assembled to study the complex problem of lodging in oats.
The approach involves the development of a mathematical lodging model based on engineering principles which describe how wind interacts with solid structures. Such a model has already been developed for wheat, and this approach is being further developed to produce a lodging model for oats. A series of measurements conducted on oat crops are used to parameterize the model.
Crop movement caused by wind is measured by tracking the movement of the crop using video cameras; this data is correlated with high-resolution three-dimensional wind data collected by sonic anemometers (see picture above). Measurement of plant characteristics relevant to lodging are also conducted on oat crops in order to provide data for the model. These characteristics include root plate diameter and root depth, stem diameter and wall thickness, the center of gravity, and natural frequency of oscillation (“springiness” of the stem).
Field experiments in which the agronomic factors which affect lodging are varied are used to test the applicability of the model in field conditions. Such experiments are designed to produce a wide range of the plant characteristics which affect lodging. Data collected from the agronomic treatments will be used to quantify the impact that changes in agronomy have on lodging risk.
Once developed, the lodging model will be used to identify the plant characteristics which have the greatest influence on lodging resistance. The scope for altering the most important plant characteristics through variety choice and crop management can then be estimated from the data collected in the field experiments and the lodging model will then be used to estimate the impact of this change on lodging risk. The lodging model will also be used to quantify the shape and strength of each plant characteristic required to enable a crop to avoid lodging in all but the most adverse weather conditions. This information will provide targets for both plant breeders and agronomists. An important function of the model will be to test how climate change will impact on lodging in oats to ensure that newly bred oat varieties will be resistant to new pressures which will result from our changing climate.
The development of a calibrated model of the lodging process in oats will facilitate the development of a fundamental understanding of the process of lodging in oat crops and how resistance to lodging can be improved. The minimization of the risk of lodging in oat crops will allow the full potential of the oat crop to be realized.
John Finnan and John Spink from Teagasc, Mohammadreza Mohammadi, Mark Sterling, and Chris Baker from the University of Birmingham, UK, and Pete Berry from ADAS High Mowthorpe.
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