Photosynthetic Assimilation, Carbohydrates in Vegetative Organs and Carbon Removal in Nut-Producing and Sap-Producing Coconut Palms

Abstract

The net assimilation rate, carbohydrate content in leaf and trunk tissues and quantum of carbon removed in sap-producing (SP) and nut-producing (NP) coconut palms were compared. The correlations between sap (toddy) yields of SP palms, and their leaf and trunk carbohydrate content; net assimilation rate; and the pre-tapping phase nut yields, were investigated as possible criteria for selecting coconut palms with potential for high toddy yields. Thirty-five-year-old coconut palms of the Tall variety (Cocos nucifera L., var. typica), at Bandirippuwa Estate, Lunuwila, Sri Lanka were used for the study. Total soluble sugar content (TSS) in leaf and trunk tissues was higher (62-73 mg g dw -1 ) than their starch content (24-41 mg g dw -1 ) in both SP and NP palms. In SP palms, TSS of leaf tissue was higher, and trunk tissue was lower, than in NP palms. The total carbohydrate (TC) content in the trunk was generally higher than in leaves of both SP and NP palms. In SP palms, the ratio of TSS : starch was higher in leaves, and lower in the trunk, than in NP palms. Net assimilation rates and carbon removal by the produce (nut or sap) was similar in NP and SP palms.There was no significant correlation between sap yields and TSS and starch contents of leaf or trunk tissues of palms, before and during tapping; and the nut yields before; and the NAR during tapping. These parameters are therefore not of predictive value for selecting coconut palms for high sap yield.

An Investigation of Yield and Quality of Coconut Inflorescence Sap in Different Coconut (Cocos nucifera L.) Genotypes under West Coast of India

“…Menon and Panldalai (1958) listed certain indicators for higher sap yield viz., palms with close set of crown, more number of leaves and strong and short petioles. Ranasinghe (2007) made similar observations in Sri Lanka, where the tappers traditionally use some visual criteria such as more number of leaves and long and relatively thin inflorescence sheaths, which make easy the bending of flower stalks without splitting. These parameters ensure sustainably high sap yields.…”

Estimation of carbon sequestration potential in coconut plantations under different agro-ecological regions and land suitability classes

“…Forests and tree plantation crops are particularly important as carbon reservoirs because trees hold much more carbon per unit area than other types of vegetation (Lasco et al, 2002;Lamade & Bouillet, 2005). Coconut, being a perennial tree crop with 50-60 years of economic lifespan, has a potential to act as a carbon sink (Jayasekara & Jayasekara, 1995;Mialet-Serra et al, 2005;Ranasinghe & Silva, 2007;Roupsard et al, 2008a,b). When accounting the contribution of terrestrial ecosystems to the global C cycle, measuring the productivity and carbon balance of various land uses is of great importance, particularly in the tropics.…”

Transitory Carbohydrate Reserves in Vegetative Organs of Coconut Under Different Growth Conditions and Its Relation with Reproductive and Vegetative Growth of The Palm

“…The organic layer was discarded and the aqueous layer containing all the water soluble compounds in leaf and ekel samples was concentrated to a volume of 5ml using rotoevaporator for sugar analysis. The total sugar content was determined by Phenol Sulphuric method (Dubois et al 1956;Ranasinghe and Silva, 2007).…”

“…However, the chemical nature and physiological role of the transitory reserves vary with the variety. Soluble sugars, mainly sucrose was found to be the main storage carbohydrate in vegetative organs of coconut (Mialet Serra et al 2005;Ranasinghe and Silva, 2007) and sugarcane (Komor, 2000), whilst starch was found to be the main reserve in many dicotyledonous tree species. In oil palm (Elaeis guineensis), glucose is an important reserve sugar, followed by starch and sucrose (Legros et al 2009a;2009b).…”

“…In oil palm, 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). The variation in the non-structural carbohydrates with tapping (artificial stimulation) was demonstrated in coconut (Ranasinghe and Silva, 2007) and rubber (Silpi et al 2007).…”