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Floral Biology of Off-season Jackfruit in South-west Region of Bangladesh

M.A. Mannan*
Agrotechnology Discipline, Khulna University, Khulna 9208, Bangladesh

K. M. Ashraful Islam
Agrotechnology Discipline, Khulna University, Khulna 9208, Bangladesh

M.R. Islam
Agrotechnology Discipline, Khulna University, Khulna 9208, Bangladesh

S.A.K.U. Khan
Agrotechnology Discipline, Khulna University, Khulna 9208, Bangladesh

Abstract/ Executive Summary:

An investigation on floral biology of off-season jackfruit germplasms was carried out during mid July 2003 to mid November 2003 at the village Shakharipara, Rupdia, Jessore. This region is considered to be the largest jackfruit growing region of South-western region of Bangladesh. Six germplasms of more or less same aged have been selected for this study. The period for the floral bud development varied from 33 to 42 days with an average 36.8 days. Six distinct sequences of spike opening was observed on foot stalk. The availability of pollen grains and receptivity of female spike ranged from 3 to 6 days (average 4.5 days) and 8 to 12 days (average 10.26 days), respectively. Emergence of anther, stigma and dehiscence of anther occurred during day and at night. The peak emergence of anther and its dehiscence occurred during 2-4 A.M. and 4-6 P.M., respectively and the peak emergence of stigma at 8-10 A.M.

Keywords: Floral biology, Off-season, Jackfruit.

Location: South-West Region of Bangladesh

Start Date: 15-07-2003

End Date: 15-11-2003

Program Area: Crop-Soil-Water Management

Commodity: Jackfruit

Objectives:

If some information could be gathered about the floral biology of jackfruit, the findings could be utilized in plant improvement program for screening and improving the unidentified local and off-season germplasms. Studies pertaining to floral biological phenomena constitute the basic information required for plant improvement program. The present study was initiated with a view to obtaining detail information about the floral biology of off-season jackfruit. It was hoped that the information would contribute to a great extent to the purpose of improvement of some of the types to establish as variety in due course of time which ultimately improve the yield and quality of jackfruit by developing a off-season variety.

Methodology:

The study was carried out during first week of July 2003 to end of November 2003 at the village Shakharipara, Rupdia, Jessore. Six of more or less same aged (18-22 years) healthy germplasms were selected for this study. Spikes on the trunk and primary branches of selected trees were tagged. Observation was made regularly at an interval of two hours during the flowering period. The following parameters were studied in the experiment.

Time required for floral bud development: The period of time that was required from the initiation of foot stalk to just before opening of the spike from spathes was considered as the time for the development of floral bud. Flowering period and peak flowering period: Flowering period of off-season jackfruit was considered as the duration between emergence of first spike (male or female) to the dehiscence of anther on last male spike or withering of stigma on last female spike, while the period of maximum number of available spike on the plant was the peak flowering period. Sequence of spike opening on footstalk, and number of spike per stalk and leafy shoot: During the flowering period the tree develops special fruiting branchlets that grow out of the trunk and branches called foot stalk. Each foot stalk bears male and female spikes. The sequence of male and female spike opening, and number of spike per stalk and leafy shoot were observed.

Time required between two successive spike opening: At the time of opening each bud was tagged in a footstalk and time period of two successive spike opening was recorded. Period from initiation of spike opening to shedding of spathe: The period from initiation of spike opening to shedding of spathe was considered as the time between opening and shedding of spathe from the spike. It was determined through day to day observation. Duration between male spike opening and anthesis: The time period between male spike opening and anthesis (emergence of anther) was recorded. The anthesis was determined by observing the selected spike in every day.

Duration of availability of pollen grains on male spike: Duration of availability of pollen grains on male spike was considered as the dehiscence of the first anther and dehiscence of the last anther on the male spike. It was determined by daily observation. Time of anthesis and dehiscence of anther: Time of anthesis and dehiscence of anther of the individual flower were studied during 24 hours. Male spikes were tagged in each plant and observed at 2 hrs interval from 6 A.M. to 6 P.M., finally the cumulative number of emergence of anther and dehiscence of anther were counted next morning (6 A.M.) with the help of a magnifying glass. Duration between female spike opening and protrusion of stigma: Duration between female spike opening and protrusion of stigma was considered as the time between opening of the spikes from the spathe and the emergence of first stigma on the female spike. It was observed by using magnifying glass. Duration of receptivity of stigmas on female spike: Duration of receptivity of female spike was considered as the number of days required for the emergence of first stigma and withering of last stigma on the same female spike. The start of receptivity of stigma was indicated by stickiness and completion by withering of individual flower on a spike. It was done by day to day observation by using magnifying glass.

Rate of emergence of stigma and duration of receptivity of flower: The rate of emergence of stigma was observed by using a magnifying glass. It was made at 2 hours interval from 6 A.M. to 6 P.M., finally the cumulative number of emergence of stigma was counted next morning (6 A.M.). The start of receptivity of stigma was indicated by stickiness. The duration of receptivity of stigma was considered as the time between the stickiness and withering of a stigma on female spike.

Source of Information: Khulna University Studies, Special Issue (1st Research Cell Conference): 75-82, 2006

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The results of the present study have provided some basic information on the floral biology, fruiting behaviour and fruit setting of off-season jackfruit. There were variations in different aspects of the study among the germplasms. However, among six germplasms in the present study, germplasm no. 5, 14 and 18 were found to be better in respect of time required for floral bud development, duration of receptivity of stigma on female spike, etc. Further trial on physico-chemical analysis is necessary to recommend the above mentioned off-season germplasms as varieties.

Knowledge Management: Journal