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Title: The use of changing plant morphology in developing a simulation model for winter wheat (Triticum aestivum)
Author: Lock, Allan Arthur
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2001
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Leaf appearance of winter wheat in relation to thermal time has been studied during the past twenty years but as yet models have insufficient accuracy for predictive use.

This project investigated different methodologies used previously to describe leaf appearance. These were applied to data collected from tagged plants to compare results from the different systems and investigate possibilities for unification and improving accuracy. The different methodologies could not be unified. Phyllochrons, measured as thermal time intervals between either leaf tip or ligule appearances, varied throughout the life of the plant, those calculated by ligule appearances produced phyllochrons least affected by seed size. Lamina length was influenced by total solar radiation received during its external appearance. Lamina extension rates, calculated as mm 0Cd-1, were correlated with solar radiation and influenced by ontogenetic rank. Calculating proportional lamina appearance values using self-referencing methodology produced fewer errors than by referencing the previous lamina, but results from both systems were influenced by seed weight. Seed weight influenced the 'tip to indent' length of a lamina, but not the 'indent to ligule' length and its effect was greatest on leaf two thereafter diminishing. The tip of the second leaf appeared earlier in plants grown from heavy seed compared with light seed.

Internal leaf development in plants was investigated by dissection. Lower ridge extension continued until awn extension occurred at the apex, indicating that final leaf number might not be determined until then. The ligule on one leaf remained synchronised to an 'indent' on the next lamina until the ligule emerged. Several developing leaf systems were similarly 'mechanically linked' and this may explain similarities between phyllochrons. The project identified that the amounts of stored or received energy available for assimilation influenced rates of leaf appearance and possibly the number of leaves. The process was undoubtedly regulated by temperature and possibly influenced by ontogenetic rank.

Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Agronomy Agronomy Plant diseases Horticulture