biologia plantarum

Biologia plantarum 49:7-15, 2005 | DOI: 10.1007/s10535-005-7015-6

High irradiance can minimize the negative effect of exogenous sucrose on the photosynthetic capacity of in vitro grown coconut plantlets

G. Fuentes¹, C. Talavera¹, Y. Desjardins², J. M. Santamaria^1,*

¹ Centro de Investigación Científica de Yucatán, Unidad de Biotecnología, Mérida, Yucatán, México

² Centre de Recherche en Horticulture, Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentatio, Université Laval, Ste-Foy, Canada

There is increasing evidence that the sucrose normally added to the culture medium affects negatively the photosynthetic capacity of plantlets. At the same time, however, sucrose cannot be eliminated from the medium, as it is required for normal in vitro growth. We argue that this is true only under the conventional light conditions of growth-rooms. In the present paper irradiance of growth-rooms was increased 10 times and although the sucrose-inhibitory effect was found at high sucrose concentrations, it was possible to grow coconut (Cocos nucifera L.) plantlets without sucrose. Those plantlets showed both high photosynthetic capacity and comparable in vitro growth to those grown with sucrose in the medium under conventional growth-room irradiance. Nevertheless, the best growth was achieved under mixotrophic conditions where at high irradiance and moderate sucrose concentrations plantlets accumulated 27 % more biomass than plantlets grown without sucrose under high irradiance and 43 and 73 % more biomass than their counterparts at low irradiance with or without sucrose, respectively.

Keywords: chlorophyll fluorescence; carboxylation efficiency; dark respiration rate; ex vitro transfer; light response curve; net photosynthetic rate

Subjects: carboxylation efficiency, photosynthesis; chlorophyll fluorescence, high PPFD; coconut, PPFD, sucrose, photosynthesis; Cocos nucifera; ex vitro transfer; gas exchange, high photon flux density; growth analysis, plant development, biomass and yield enhancement; in vitro culture, acclimation, adaptation, to ex vitro transfer; in vitro culture, gas exchange, high irradiance; in vitro culture, sugar sources; nutrient medium Y3; photon flux density; quantum efficiency, apparent; root, growth parameters; sucrose, high PPFD; sucrose, in vitro culture

Received: January 20, 2004; Accepted: October 18, 2004; Published: March 1, 2005  Show citation