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Title: The response of barley to some climatic factors in the north of Scotland
Author: Yogaratnam, Velupillai
ISNI:       0000 0001 3575 3449
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1976
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Glass house and field experiments were conducted in the Worth of Scotland to evaluate the effects of some climatic factors on the growth of barley. Rate of seedling emergence showed a positive linear relationship with soil temperature and an equation liras calculated linking the two factors. Between 3°C and 12°C there was a difference of approximately 28 days in time to germinate. Leaf emergence up to the 4th leaf stage was positively related to soil temperatures but beyond this stage air temperature, soil temperature, day length and light intensity all had a positive effect. Low soil temperature delayed leaf emergence, decreased plant height and increased tillering. High light intensity increased tillering. Tiller number was highly negatively correlated with rate of leaf emergence and also showed a lesser negative correlation with plant height. Initially plant height increased with increased soil temperatures, but at the later stages of growth, plant height was constant over a wide range of temperatures. Although soil temperatures around 20--24°C promoted leaf emergence and hence early flowering all other growth processes were reduced. Nitrogen delayed seedling emergence especially at low temperatures of 3--6°C, but showed a quadratic trend for plant height and tillering. Under high temperatures effect of nitrogen in tillering was not significant. Flowering was speeded up with increased soil and air temperatures but accelerated flowering reduced tillering. Low soil temperatures and low light intensities up to the 4th leaf stage was necessary for large leaves but beyond this stage high soil temperatures and low light intensities were required. Differences in the number of days to flowering between varieties sowing dates or years were mainly due to the variation in the number of days between seedling emergence and the fourth leaf stage. Other stages were much less variable. Variation in growth and development at different sowing dates could be satisfactorily explained by temperature. Late sowing gave quick germination and fewer tillers due to warm soils, while rate of leaf emergence was accelerated by both higher soil and air temperatures leading to early flowering. This early flowering also helped to suppress tillering. aSite differences in growth and flowering could also largely be explained on the same basis as for sowing dates, but there were discrepancies in tillering between sites that could not be satisfactorily explained. Day length appeared to be unimportant in controlling the rate of development, but provided additional light. Shading reduced tillering very markedly but produced larger leaves. Accumulated day degrees were shown not to be very effective in helping to explain differences in barley growth due to temperature. Particular growth stages were not dependent on attaining a given number of day degrees. The work has shown that in the North of Scotland at least, barley growth and development are complex parameters that can largely be explained in relation to air temperature, soil temperature and light. The weather from, germination to emergence of the 4th leaf seems critical in determining tillering and flowering. Differences in barley development between sites and sowing dates and years can be explained in terms of climate.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available