Understanding and assessing the probability of oat lodging with respect to current and future climates

Mohammadi, Mohammadreza ORCID: 0000-0002-6376-0029 (2021). Understanding and assessing the probability of oat lodging with respect to current and future climates. University of Birmingham. Ph.D.

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Abstract

This research aims to examine lodging (the failure of crops by wind and rain) in oats and hence to improve the understanding of lodging resistance for this particular crop. The applicability of a lodging model combining meteorology, agronomy, and engineering to describe lodging in oats is examined and the assumptions embodied in the model are evaluated. In order to provide supporting data to examine the lodging model, a number of field experiments were undertaken which were carried out in the Republic of Ireland to investigate the dynamic/aerodynamic parameters (natural frequency, damping ratio, and drag area). Moreover, standard husbandry treatments were applied on crops to provide realistic conditions for growing oats and to ensure that the outcomes are broadly applicable. A number of agronomic measurements were undertaken to provide the required input data for the lodging model. Consequently, the results of agronomic and dynamic/aerodynamic data enabled the lodging model to be modified/calibrated for oats and systematic parametric analysis of influential parameters was undertaken. It is demonstrated that the drag area is the most influential factor for both stem and root lodging. Additionally, stem yield stress and the number of stems per plant in the case of stem lodging, and the root diameter for root lodging, are identified to have crucial roles. Furthermore, through calibrating anchorage system failure models, it is found that both root diameter and depth are influential in the failure anchorage resistance in oats. This research also shows crop growth and panicle interlocking in the last growth stages, causes a decrease in the natural frequency and damping ratio but increases the drag area, which results in a higher probability of lodging in the growth stages before the harvest. Moreover, using a combination of resistant variety with low seeding rate, low nitrogen rate and Plant Growth Regulator (PGR) application, are found to effectively reduce the lodging likelihood.

The lodging model was also used to evaluate the lodging probability by using the wind and rainfall cumulative density functions (CDFs). In order to evaluate the wind and rainfall CDFs, the historical data for June and July (the period corresponding to key lodging season) from 38 meteorological stations in the British Isles, are studied. Additionally, climate projections for the next six decades in the United Kingdom and the Irish Republic generated by the UK climate change projections (UKCP18) are examined and future wind and rainfall CDFs are identified. Results show that the projected climate changes during the peak growing period (June to July) in the next three decades are in the range which might occur as a result of different management/plant varieties.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):