Aspects of heterophylly in Morus alba L.
Item
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Title
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Aspects of heterophylly in Morus alba L.
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Identifier
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AAI3008847
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identifier
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3008847
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Creator
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MacMillan, Rosemary Jean.
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Contributor
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Adviser: Dwight T. Kincaid
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Ecology | Biology, Plant Physiology
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Abstract
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These experiments were undertaken to test the null hypothesis that there is no difference between lobed and unlobed Morus alba L. leaves beyond the obvious morphological one. Physiological measurements of lobed and unlobed leaves were made of cloned saplings of Morus alba two years in succession. A droughting experiment was added in the second year, as was a mature (dbh 26 cm) tree. Measurements included net photosynthetic rate (Pnet), transpiration rate, stomatal conductance, water use efficiency (WUE), and leaf water potential. Significant differences were observed. Two-lobed leaves had higher Pnet production than unlobed leaves.;Five hundred Morus alba leaves on street trees in Manhattan and the Bronx in New York City, and in Dutchess county (90 miles north of New York City) were measured for leaf chlorophyll content, leaf specific mass (LSM), internodal distance, internodal circumference, leaf area, petiole length, blade length, blade width, perimeter, dissection index, and leaf complexity. Significant differences were found. Lobed sun and shade leaves had less blade area than unlobed leaves, more chlorophyll, and were more proximally situated on a shoot.;A census was made of every leaf of 18 saplings and of selected shoots from other trees to investigate patterns in lobing. A highly significant correlation was found between shoot side and lobe(s) side. Lobed leaves on the left side of the shoot were far more likely to have lobes on their left side and vice versa. It was established that overall on a plant, leaves are bilaterally symmetrical in terms of numbers of lobes.;Stomatal density and anatomy were measured for lobed and unlobed leaves in sun and in shade, and with added nitrogen and with severely reduced nitrogen nutrition. More and larger stomates were observed in unlobed leaves in sun plants and in nitrogen supplied plants; more and larger stomates were found in lobed leaves in shade plants and in nitrogen deprived plants.;Overall, it was shown a lobed Morus alba leaf is a different physiological, morphological (beyond lobing), and anatomical organ than a unlobed Morus alba leaf.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
