CO2 exchange rate of apple fruitlets before the abscission

• Published in: Zbornik Biotehniške fakultete Univerze v Ljubljani. Kmetijstvo (1990) no. 71
• Main Authors: Stopar, M, Gregorcic, A. (Agricultural Institute of Slovenia, Ljubljana (Slovenia), Batic, F. (Ljubljana Univ. (Slovenia). Biotechnical Fac., Agronomy Dept.)
• Format: Journal Article
• Language: English
• Published: 1998
• Subjects: 6-BENZILADENINA; 6-BENZYLADENINE; ABSCISION; ABSCISSION; ANA; ANABOLISM; ANABOLISME; ANABOLISMO; CARBON DIOXIDE; DIOXIDO DE CARBONO; DIOXYDE DE CARBONE; ECHANGE GAZEUX; FRUCTIFICACION; FRUCTIFICATION; FRUITING; GAS EXCHANGE; INTERCAMBIO DE GASES; MALUS PUMILA; NAA; OMBRAGE; SHADING; UMBRIA
• ISSN: 1408-340X

Fruit CO2 exchange at the time of fruit setting period was evaluated on mature cv. 'Jonagold' apple trees after 4 days artificial shading with 90 % photosynthetic photon flux (PPF) reduction and after NAA 15 ppm and BA 50 ppm applied immediately after the end of shading. Light reduction which accelerated fruitlets abscission very quickly had a depressive effect on fruits CO2 dark respiration rate (Rd) and gross assimilation rate (Ag) 3 days after the end of shading. Similarly, reduced Rd and less negative net CO2 assimilation rate (A) was recorded on fruitlets 7 days after NAA and BA application what is explained as a diminished metabolism of fruits starting with abscission. The fruitlets from shaded trees, which did not tend to abscission any more, showed an enhanced Rd and more negative A on 7th or 8th day after the end of shading. Ethylene evolution from fruits 2nd and 7th day after NAA 15 ppm application was enhanced comparing to control fruits. BA 50 ppm enhanced ethylene evolution on 2nd day after spraying, however on 7th day the ethylene evolution was lower than in control fruits. Healthy, not to drop inclined fruitlets retained on trees 7 days after shading treatment, showed stronger fruit ethylene production.