Abstract
The study evaluated the non structural carbohydrate reserves in vegetative organs and vegetative and reproductive growth rates of a 25 year old Tall x Tall coconut (Cocos nucifera L) during the peak season of coconut yield (May/June) under S2 and S4 Land Suitability Classes (LSC) in three Agro Ecological Regions (WL3, IL1a and DL3). Trunk (inner and outer), root (new roots and mature roots) and leaf samples (petiole, leaf blade and leaf ekel from 9th, 14th and 22nd fronds) were collected, total soluble sugars (TSS) and starch concentrations were analyzed and TSS and starch reserves at palm level were estimated. Growth rate of trunk and leaves (vegetative) and developing nuts of all bunches of a palm (reproductive) were measured. The highest (3.86 kg month-1) and the lowest (0.81 kg month-1) reproductive growth rates and the highest (3.8 kg month-1) and the lowest (2.1 kg month-1) vegetative growth rates were found in the palms grown under S2 and S4 LSC in the DL3, respectively. There was a constant vegetative growth rate of 3.3 kg month-1 for the palms in WL3 and IL1a irrespective of the AER or LSC. The most dominant nonstructural reserve substance in the vegetative organs of coconut was soluble sugars (TSS) and the starch concentration was approximately half the TSS concentration in all vegetative parts irrespective of the AER or the LSC. TSS and starch showed a marked pattern of distribution, with highest concentration in trunk (114-134 mg g-1 TSS and 60-83 mg g-1 starch), intermediate in leaves (69-117 mg g-1 TSS and 33-69 mg g-1 starch) and lowest in roots (22-79 mg g-1 TSS and 17-33 mg g-1 starch). The highest TSS and starch reserves in leaf compartments (kg per palm) were found in the S2-grown palms of the DL3 which had the highest reproductive and vegetative growth rates during May-June season. DOI: http://dx.doi.org/10.4038/cocos.v19i2.4753
Highlights
Coconut (Cocos nucifera L.) is an arborescent, monocotyledonous species with indeterminate growth, producing nuts continuously over several decades
Source-sink imbalances were mainly buffered by fluctuations in nonstructural carbohydrate reserves in the stem (Legros et al, 2009a; 2009b) whereas in coconut it was partly compensated by transitory reserves in leaf petiole (Mialet-Serra et al 2008)
There is a variation in rainfall, temperature and solar radiation intensity within a year and this pattern differs with the Agroecological Regions (AER)
Summary
Coconut (Cocos nucifera L.) is an arborescent, monocotyledonous species with indeterminate growth, producing nuts continuously over several decades. The intermediate zone of the coconut triangle has the best combination of rainfall and solar radiation for the performance of coconut The information on the non-structural transitory carbohydrates of vegetative organs of coconut in different agroecological regions and land suitability classes, during different seasons of the year (under naturally imposed varying source-sink ratios) and its relation with reproductive and vegetative growth of coconut palm is not available todate. The objectives of this study were to compare the carbohydrate reserves (mediumterm and short-term, concentrations and bulk content at palm level) and vegetative and reproductive growth rates of coconut palms under two land suitability classes (with different potential for growth of coconut) in three Agro Ecological Regions (where there are distinctive differences in climate conditions for coconut), during the peak period for coconut yield (May/ June season)
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