ELSEVIER Scientia Horticulturae 65 ( 19%) 229-238 SCIENTIA HORTlCULTuRk Growth and physiological processes of young starfruit ( Averrhoa carambola L.) plants under soil flooding Mohd Razi Ismail * , Khuzaimah Mohd Noor zyxwvutsrqponmlkjihg Depanment of Agronomy and Horticulture, Uniuersiti Perranian Malaysia, 43400 Set&q. Selangor, M alay sia Accepted 8 February 19% Abstract Soil flooding decreased leaf area and dry weight of young starfruit (Averrhoa curumbolu L) plants after 5 days from the start of flooding. Leaf senescence was promoted by soil flooding and all leaves abcised after 20 days of flooding. The changes in leaf water potential in flooded plants followed two distinct phases; the first where leaf water potential was maintained or increased relative to the control for a period of approximately 15 days, and the second phase involving a decline in leaf water potential. Stomata1 resistance was increased 24 h after start of flooding. Photosynthetic rate declined with soil flooding, and reached the compensation point approximately 16 days from start of flooding. An investigation on the effect of post-flooding treatments showed growth was permanently impaired in plants pre-exposed to 14 days of soil flooding. An increase in flower number was associated with soil flooding. The recovery of stomata1 resistance in plants flooded for 7 days occurred 3 days after soil drainage. Plants that were exposed to 14 days flooding showed decreased stomata1 resistance after relief of the flooding, but did not reach the value of the control plants. The photosynthetic rate of flooded plants also showed signs of recovery after flood relief. The relationship between leaf water potential and stomata1 resistance of flooded plants is examined. Keywords: Auerrhoa carambola; Flooding; Water relations; Stomatal response; Photosynthetic rate 1. Introduction Flooding stress results in many detrimental morphological and physiological changes in plants, including increased root mortality and reduced root metabolism. The resulting l Corresponding author. 03044238/%/$15.00 Copyright 0 1996 Elsevier Science B.V. All rights reserved. PII SO304-4238(96)00897-7