Relationship of urban dust precipitation on pollination and fruit falling of Mangifera indica and Litchi chinensis in Dhaka District, Bangladesh

Abstract

A study was conducted on the relationship of road-side dust on pollination and fruit falling of Mango (Mangifera indica) and Litchi (Litchi chinensis) from February to May, 2014. Trees were selected based on three different exposures- high, dusty (roadside), Medium dusty (100m from the road) and low dusty (200 m from the road). Number of flowers, percentage of successfully pollinated flower, rate of fruit falling at initial stage and dust precipitation per day per leaf was 940.27±122.01, 1.55%, 62.94% and 4.18 mg in mango and 408.03±77.51, 3.74%, 74.52% and 3.16 mg, respectively in litchi was found. There was, in fact no correlation between dust precipitation and rate of successful pollination (r= -0.096, df=36 for mango and r= - 0.02, df= 22 for litchi). The correlation was weak and positive between dust weight and fruit falling rate (r=0. 22, df=36 for mango and r= 0.4, df=22 for litchi) at the initial stage. Mechanical factors cause fruit falling after its formation, not the dust, up to the recorded level of precipitation. 23 pollinator insect species were recorded randomly. No Significant variation was found (α= 0.05) among dust precipitation and successful pollination rates at different dust exposure. But in fruit falling after formation, variations have been noticed.