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Studies on Blossom Biology and Sex Ratio in Jackfruit

S. Majumder
Department of Horticulture. Bangladesh Agricultural University. Mymensingh-2202

M. A. Hossain
Mymensingh Agricultural Institute. Sadar, Mymensingh

M. M. Hossain
Faruq Fertilizers Ltd. Dhaka

A.K. Saha
0FRD, Rangpur

M A Haque
Department of Horticulture.Bangladesh Agricultural University. Mymensingh-2202

Abstract/ Executive Summary:

An investigation on blossom biology and sex ratio in jackfruit was carried out during February 2000 to May 2001 at Jackfruit Research Project, Bangladesh Agricultural University, Mymensingh. Eight germplasm of same age (about 12 years) were selected for the study. The period for the floral bud development varied from 51 to 75 days with an average of 59.4 days. Six different sequences of spike opening was observed on foot stalk. The availability of pollen grains and receptivity of female spikes ranged from 4 to 7 days (av.5.3 days) and 19 to 32 days (av. 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 PM and 4-6 PM respectively, and the peak emergence of stigma at 8-10 AM. Sex ratio was higher (32.94:1) at the early part of the flowering season than later (7.03:1). Higher number of male and female spikes was borne on primary and secondary branches than the rest. The branches in the east side produced higher number of both male and female spikes and also higher sex ratio (15.3:1) while lowest (9.1:1) in the north.

Keywords: Blossom biology, Sex ratio and Jackfruit

Location: Jackfruit Research Project, Department of Horticulture, Bangladesh Agricultural University, Mymensingh

Start Date: 00-02-2000

End Date: 00-04-2001

Program Area: Variety and Species

Commodity: Jackfruit

Objectives:

i)To study the floral bud development, flowering season, blooming pattern, time of anthesis and dehiscence, period of availability of pollen grains on a male spike, emergence of stigma and receptivity of female spike;

ii) To study sex ratio and their distribution in relation to direction of branches and on different sections and different sections of plant.

Methodology:

The study was conducted in the orchard of Jackfruit Research Project, Department of Horticulture, Bangladesh Agricultural University, Mymensingh during the period from the February, 2000 to April, 2001. Eight jackfruit germplasm (Nos 14, 16, 25, 29, 30, 45, 46, 58) were selected from the orchard for present study. They were of same age similar in size, healthy and received uniform cultural management. The soil of the orchard was silty loam under the old Brahmaputra flood plain. It was fertile and well drained, and slightly acidic with pH varying from 5.5 to 6.8 (BARC, 1989). The period from initiation of flowering shoot to reach the stage of opening of the spike coming out from spathes was considered as the time for the development of floral bud. The observation was made by tagging 5 footstalk on trunk and scaffold limbs starting from December' 2000 to February' 2001 to opening of first bud in each footstalk. Flowering season of jackfruit was considered as the duration from emergence of first spike (both male and female) to the dehiscence of anther on last male spike or withering of stigma on last female spike. Peak flowering season was also considered the duration while maximum number of spike was available on the plant. The flowering and peak flowering season were observed and recorded by visiting the orchard time to time in the morning. During the following period the tree develops special fruiting branch lets that grow out of the trunk and branches called footstalk. The sequence of spike opening, and number of spike per stalk and leafy shoot was observed and recorded time during the period. 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 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 of receptivity of female spike was considered as the number of days required for the receptivity 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. 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 were 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. Sex ratio means ratio of male and female spikes in jackfruit tree. It was recorded at 15 days interval during February to March '2001. All the male and female spikes were counted among germplasm. Number of male and female spikes also counted in cumulative form during the above period in relation to direction of branches and on different sections (trunk, and branches) of plant. The ratio of male and female spikes was calculated as; Sex ratio (male:female)=(Total number of male spikes/ Total number of female spikes).

Source of Information: Bangladesh Journal of Environmental Science. Vol. 13, No.1, pp: 91-96, 2007

Article Link (Online Journal):

Funding Source:

1. United States Agency for International Development

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The highest number of male and female spikes (1108+73=1181) was found in the branches situated in the East side producing higher number of fruit set followed by West side and the lowest (310+34=344) in the North side. The sex ratio was also the highest 15.3: 1) in East side and the lowest 9.1: 1) in North.

Knowledge Management: Journal