Responses of gas-exchange rates and water relations to annual fluctuations of weather in three species of urban street trees

Paclobutrazol is a tree growth regulator that is frequently applied by arborists to control tree growth in utility rights of way. Paclobutrazol is also marketed to mitigate tree stresses associated with urban environments. In this study we applied paclobutrazol as a soil drench to honeylocust (Gleditsia triacanthos L var. inermis (L.) Zab.) and Callery pear (Pyrus calleryiana Decne.) trees planted as street trees on two sites in Lansing, Michigan USA. We evaluated physiological and morphological responses for two years after treatment. Application of paclobutrazol increased SPAD chlorophyll index of trees of both species in both years, compared to untreated control trees. Application of paclobutrazol increased leaf water potential of trees on one study site (Downtown) but not the other (Old Town). Paclobutrazol increased gas exchange (net photosynthesis and stomatal conductance) of Callery pear trees on one of four measurement dates (gas exchange was not measured on honeylocust trees). Leaf size of Callery pear trees was reduced following paclobutrazol application whereas leaf size of honeylocust trees was unaffected by paclobutrazol. These results indicate that paclobutrazol can help to reduce stress of trees and improve physiological function under urban conditions. However, paclobutrazol should be viewed as part of a suite of options for arborists and landscapers to manage trees on stressful sites, rather than as a replacement for proper overall care.

Download Full-text

Effects of chloride and sodium on gas exchange parameters and water relations of Citrus plants

Physiologia Plantarum ◽

10.1034/j.1399-3054.1992.860116.x ◽

1992 ◽

Vol 86 (1) ◽

pp. 115-123 ◽

Cited By ~ 3

Author(s):

J. Banuls ◽

E. Primo-Millo

Keyword(s):

Gas Exchange ◽

Water Relations ◽

Gas Exchange Parameters ◽

Exchange Parameters

Download Full-text

Gas Exchange and Water Relations of ‘Olaf’ Spring Wheat 1

Crop Science ◽

10.2135/cropsci1983.0011183x002300030023x ◽

1983 ◽

Vol 23 (3) ◽

pp. 541-546 ◽

Cited By ~ 2

Author(s):

Jack A. Morgan ◽

W. O. Willis

Keyword(s):

Gas Exchange ◽

Water Relations ◽

Spring Wheat

Download Full-text

Comparative Study on Gas Exchange, Water Relations and Leaf Anatomy of Two Olive Cultivars Grown under Well-Irrigated and Drought Conditions

Zeitschrift für Naturforschung C ◽

10.1515/znc-1999-9-1011 ◽

1999 ◽

Vol 54 (9-10) ◽

pp. 688-692 ◽

Cited By ~ 4

Author(s):

Konstantinos Chartzoulakis ◽

Angelos Patakas ◽

Artemis Bosabalidis

Keyword(s):

Gas Exchange ◽

Water Relations ◽

Volume Fraction ◽

Spongy Parenchyma ◽

Intercellular Spaces ◽

Palisade Parenchyma ◽

Mesophyll Cells ◽

Olive Cultivars ◽

Olea Europea ◽

Leaf Anatomical Characteristics

The effect of water stress on gas exchange, water relations and leaf anatomical characteristics have been studied in two olive cultivars (Olea europea, L. cv. ‘Koroneiki’ and cv. ‚Mastoidis’). Photosynthetic rate as well as stomatal conductance were decreased in stressed plants. Osmotic potential (π) declined rapidly in stressed plants indicating their ability for osmoregulation. Bulk modulus of elasticity (ε) was significantly higher in stressed compared to well irrigated plants. The volume fraction of intercellular spaces of the upper palisade parenchyma, the spongy parenchyma as well as the lower palisade parenchyma were significantly lower in stressed compared to well irrigated plants. On the other hand, the density of mesophyll cells in the upper palisade parenchyma, spongy parenchyma and lower palisade parenchyma increased significantly in stressed plants

Download Full-text