Effects of fungicide and insecticide mixtures on apple tree canopy photosynthesis, dark respiration and carbon economy

Trees of apple (Malus domestica Borkh.) with 'Starkspur Supreme Delicious' as the scion grafted on nine different rootstocks (Ottawa 3, M.7 EMLA, M.9 EMLA, M.26 EMLA, M.27 EMLA, M.9, MAC-9, MAC-24, OAR 1) were studied in their 8th and 9th years. Canopy seasonal development and its light interception followed by fisheye (hemispherical) photography showed that rootstock affected the amount of structural wood, the rate of canopy development, and final leaf area. However, rootstock did not affect the sigmoidal pattern of canopy development. Light interception was linearly correlated with tree dimensions and yield. Leaf net photosynthesis (Pn) of trees on dwarfing rootstocks tended to be lower than Pn rates of trees on more vigorous rootstocks. Rootstock did not affect the scion Pn response to different illumination levels. Shoot leaves, spur leaves on spurs without fruit (S − F), and spur leaves on spurs with fruit (S + F) from trees on M.26 EMLA and OAR 1 showed no differences in Pn rates. However, for both rootstocks, shoot leaves had the highest Pn rate, S + F the lowest, and S − F leaves had intermediate values. Key words: light interception, fisheye photography, leaf type.

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Light Thresholds for Apple Tree Canopy Growth and Development

HortScience ◽

10.21273/hortsci.26.8.989 ◽

1991 ◽

Vol 26 (8) ◽

pp. 989-992 ◽

Cited By ~ 13

Author(s):

Curt R. Rom

Keyword(s):

Growth And Development ◽

Apple Tree ◽

Tree Canopy

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Growth Control of Upper Part in ‘Fuji’/M.9 Apple Tree Canopy by Cutting Time of Trunk and Plant Growth Regulators

Korean Journal of Environmental Agriculture ◽

10.5338/kjea.2018.37.2.15 ◽

2018 ◽

Vol 37 (2) ◽

pp. 87-96

Author(s):

Dong-Hoon Sagong ◽

Jae-Wang Lee ◽

Tae-Myung Yoon

Keyword(s):

Plant Growth ◽

Plant Growth Regulators ◽

Growth Regulators ◽

Apple Tree ◽

Growth Control ◽

Tree Canopy

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An Exploration of the Carbon Economy of the Tobacco Plant. III. Gas Exchange of Leaves in Relation to Position on the Stem, Ontogeny and Nitrogen Content

Functional Plant Biology ◽

10.1071/pp9740551 ◽

1974 ◽

Vol 1 (4) ◽

pp. 551 ◽

Cited By ~ 9

Author(s):

HM Rawson ◽

C Hackett

Keyword(s):

Gas Exchange ◽

Nitrogen Content ◽

Time Course ◽

Dark Respiration ◽

Tobacco Plant ◽

Net Photosynthesis ◽

Developmental Time ◽

Leaf Ontogeny ◽

Similar Time ◽

Carbon Economy

Tobacco plants were grown in sunlit, controlled-environment cabinets, and their growth and gas exchange were followed from shortly after emergence to 90 days from sowing. There were three major findings: 1. Summed over all leaves, dark respiration remained at 6-7% of net photosynthesis for a lengthy period (50-90 days from sowing), but in younger plants the fraction reached as high as 18%. 2. In the 12 leaves monitored from their emergence to full expansion, net photosynthesis (Pn) followed a similar time course, even though the first and last leaves in this group emerged nearly 40 days apart and there was a 100-fold difference in final area (Amax). For a sequence of nine of these leaves, the agreement was so close that their photosynthetic histories could be represented by a single relationship with developmental time. Peak Pn was consistently attained at about 37% Amax, when peak dA/dt occurred, and it was held for only 3-5 days. The subsequent decline reduced Pn to less than one-third of peak Pn at Amax. 3. Data for the nitrogen content (w/w) of the leaves after 37% Amax could be combined in a manner similar to that described for Pn. Pn, nitrogen content and leaf ontogeny were therefore directly related after peak Pn had been attained. The bearing of these findings on the study of photosynthesis in dicotyledonous species is discussed.

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