Abstract:The final yield of coconut (Cocos nucifera L.) is determined by early fruit set. Thus understanding the factors controlling fruit set including climate change is of importance for assessing the yield and its accurate prediction. This study assessed the survival pattern of female flowers produced in different months of the year, the effects of climate factors during early phase of flowering and the competition for assimilates from previously formed fruits on the fruit set of newly opening inflorescences in a 25 -26 year-old coconut plantation in the Intermediate Zone (IL 1a ) of Sri Lanka over a period of three years. The rate of fruit survival since the onset of flowering to maturity varied with the month of inflorescence opening. Abortion of fruits after three months from inflorescence opening was negligible. The optimum (T opt-in vitro ) and maximum (T max-in vitro ) temperatures for in vitro pollen germination were 28 ºC and 39.7 ºC, respectively. The fruit set of an inflorescence/s opened in a given month (number of set fruits palm -1 month -1 ) was negatively correlated with the total reproductive dry matter requirement of the palm (TDMR) of the month of inflorescence/s opening (first month), and the number of high temperature days (T max ≥ 33 ºC) during the first three months of inflorescence opening, whilst it was positively correlated with the number of female flowers produced in the inflorescence. There was a highly significant correlation between the monthly fruit set (at three month stage) and the corresponding harvested fruit yield palm -1 month -1. The lag period between flowering (opening of the female phase) and fruit maturing was eleven months.
Two field experiments were conducted in gravelly soils (Andigama series) in Sri Lanka to investigate the effect of different mulches and cover crops, utilized to conserve soil moisture, on water status, gas exchange and related soil parameters of coconut palms {Cocos nucifera L. var typica).The results revealed that mulching only the manure circle was not effective in improving the palm water status, gas exchange and soil water status during dry periods in Andigama soil series (gravelly soils). The mulches tested were coconut husks, coir dust, straw, black polythene and dried coconut fronds. The palms were equally sensitive to soil water depletion and responded to the water deficit by increasing the stomatal resistance irrespective of the mulch treatment. When the manure circle was mulched with dried coconut fronds, and the rest of the land was also mulched with a five cm thick layer of coir dust, the palms showed an improved gas exchange ability than palms growing in bare land or with cover crops during the dry period.
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 S 2 and S 4 Land Suitability Classes (LSC) in three Agro Ecological Regions (WL 3 , IL 1a and DL 3 ). Trunk (inner and outer), root (new roots and mature roots) and leaf samples (petiole, leaf blade and leaf ekel from 9 th , 14 th and 22 nd 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 S 2 and S 4 LSC in the DL 3 , respectively. There was a constant vegetative growth rate of 3.3 kg month -1 for the palms in WL 3 and IL 1a 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 S 2 -grown palms of the DL 3 which had the highest reproductive and vegetative growth rates during May-June season.
The present study determined the dry matter (DM) requirement for potential growth (PGR), growth respiration (R g) and maintenance respiration (R m) offruits, leaves, stem and root system of adult coconut palms (25-26 years) ofTall x Tall cultivar under resource-unlimiting conditions. The total OM requirement of a palm was about 21 kg/palm/month and 63% ofthat total was required for growth and respiration of vegetative organs (leaves, stem and roots) whilst the rest (37%) was for fruits. Similarly, the OM required for respiration (62%) was nearly two third ofthe total requirement of a palm and the balance 38% was required for growth of organs. The total dry matter requirement (TOMR) of individual fruits varied with developing stage and TOMR offruits / palm varied between months and years depending on the fruit load of different development stages. Irrespective of the year, TOMR of fruits was highest during November to February (about 10-11 kg/palm/month) and lowest in June-july (about 5-6 kg/palm/month). However, the OM requirement of vegetative organs (a total of approximately 13 kg/palm/month) did not vary between months.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.