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Title: Studies on yield and yield components of barley
Author: Al-Falahi, Tariq Salih
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1971
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A series of pot and field experiments was carried out in the north of Scotland in 1969 and 1970 to investigate which yield components of barley were most closely related to yield and to explain yield difference between years, sites, nitrogen and varieties. These trials were augmented by experiments in controlled-environment cabinets. The degree of correlation between yield and different yield components varied between years, sites, varieties and nitrogen. This can partly be explained in terms of intra-plant competition at different stages of growth. In general, nitrogen increased yield by increasing the number of tillers and ears but occasionally had a positive effect on other components. Splitting of the nitrogen dressing had no significant effect. There was a constancy of yield over a wide range of conditions but there were large differences in yield components which were not consistent and which could not be predicted. The only correlations which were regularly significant were those between tiller or ear number and yield within any one site. Between sites these correlations did not always apply. 4. Changes in population density altered many of the yield components but there was a constancy of yield above a certain minimum density. 5. Delaying sowing had the effect of reducing yield and also the yield components except for number of grains per ear. Sowings in May and June gave very low yields because of greatly reduced tiller number. 6. In controlled environment experiments, tiller number increased with temperature up to 23°C which was the highest temperature tested. The weight of the plant at the flag-leaf stage showed a decline below 8°C and above 18°C. At photoperiods of 24 and 16 hours, the flag-leaf was produced in 4--5 weeks from sowing but the number of tillers was low. With 8 hours light, the flag-leaf was not produced until 8 weeks after sowing but tillering was profuse. This was true even when total light intensity at 8 hours equalled that at 16 hours. These results suggest that flowering is under the control of photoperiod rather than temperature. 7. These investigations have revealed how yield components in barley affect yield but suggest that such knowledge cannot be made use of in agriculture except to suggest the use of adequate nitrogen and early sowing which is already well known. Intra-plant competition ensures a constant yield over a wide range of conditions above certain threshold values.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available