MenuISSN (0970-2083)
ISSN (0970-2083)
Dept of Environmental Sciences, Bangalore University Bangalore 560 056, India
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Air pollution has become a major threat to the survival of plants in the industrial vicinity. The premature falling of plant parts like leaves, flowers and fruits is referred to as abscission. Generally physiological and anatomical changes result in reponse to certain disturbances, which is considered as stressor that can induce an alteration in plant physiology resulting in the premature falling of flowers and fruits. Hence a comprehensive study has been made in stone quarry area to understand the flowering and fruiting abscission pattern. The study results revealed the effect of quarry dust on the flowering and fruiting pattern.
Flower and Fruit abscission and Quarry dust, Air pollution
The effect of air pollution on the morphology, physiology and biochemistry of plants have long been recognized. (Koziol et al. 1984; Treshow., 1985; Ahamed et al. 1988). Studies have been made on the impact of particulate matter in the case of kiln dust on garden fruit (Pierce, 1910; Anderson, 1914). In addition several other studies have highlighted the effect of dust on the morphological and physiological aspects of plants (Maiti, 1992). The physiological cause of abscission is however still largely unknown. Abscission of fertilized flower may also be regulated by the availability of resources (Stephenson, 1981; Lee, 1988). In citrus species high rate of flower abscission is correlated with lower level micronutrients such as Zinc (Kaska, 1989). Similarly decrease in water potential could increase abscission due to increased ethylene synthesis (Apelbaum et al. 1981). Jiang et al. (1993), openied that darkness or shade often increases flower fall. Various other environmental factors such as elevated temperature and low soil water potential (Cochran, 1936) are also known to stimulate flower abscission. Cameran et al. 1981; Weis et al. (1988) are of the view that exposure of plants to exogenous ethylene enhances flower and fruit abscission (Yager et al. 1958). The mechanism of the abscission at the cellular level was worked out by various scientists in different plant species (Wauter et al. 1997).
Although several reports are available from Indian subcontinent (Das et al; 1978, Chaphekar et al. 1982) and abroad (Bach; 1972, Bennet; 1973, Lerman et al. 1975), so far no comprehensive study has been made to discern the qualitative effect of dust on plant parts growing in a deteriorated environmental condition of a stone quarry area. Hence the present study has been undertaken to explore the effect of quarry dust pollution on flowering and fruiting abscission pattern.
The criteria used for the selection of the appropriate study site is ‘dust fall’ and greater abundance of vegetation in selected quarry locations from Bangalore district. Most prevalent plant species (Muntingia calabura) was sampled. The same species collected away from the quarry area served control. The plants were sampled at a distance of 100 to 500 from the study site. The dust deposited on the plant parts were estimated by washing method. (Pattanayak et al. 1994). In each tree branches were selected randomly on the observation on the flower and fruit abscission was recorded. Similar observation was made in the controlled studies. An attempt has also been made to highlight the biochemical effect of foliar dust deposition. Correlation among Fdd and flower and fruit abscission were made by following the Standard procedures (Agarwal et al. 1988, Tiwari et al. 1989).
The data are presented in Table 1. Regular monitoring of the sampled plants revealed that quarry dust which cumulatively gets deposited on the plant parts leads to premature falling or abscission of flowers and fruits. It is evident from the experimental data that the flower abscission ranged form the 18.4 to 62.6% and the fruit abscission ranged from 16.3 to 46.4 %. The foliar dust deposition ranged from 15.9 g/m² at 500m, 4.62 % g/m² at 100m distance from the quarry site.
Table 1 Percentage of flower and fruit obsession pattern in Muntingia calabura (Bettahalsur)
Table 2 Percentage of flower and fruit abscission pattern in Muntingia calabura (Control)
In Kallugopanahalli village the flower abscission ranged form11.9 to 43.5% and fruit abscission from 11.7 to 40.0%. The Foliar dust deposition ranged between 1.5 to 6.26 g/m² at 500m and 100m distance respectively.
In Basavanahalli village the percentage of flower abscission ranged from 11.9% to 25.0% and the fruit abscission ranged from 8.5 to 17.8% taken in the different directions between 100m and 500m respectively. The Foliar dust deposition ranged between 1.64 to 4.52 g/m² at 500m and 100m distance respectively, in control studies which is carried out away from the stone quarry area.
Dust may act as environmental stress in plants and trigger numerous phytoharmones that regulate abscission. There is also possibility of the interference of Ethylene, Auxin, Gibberellin and Cytokinin which cause flower fall as shown in many studies (Clifford et al. 1982). It is known that dust fall induces flower and fruit shedding. Higher foliar dust deposition may induce obstruction in light pathway, stomatal function etc. This may account for larger reason for the failure of flowering and fruiting among plants growing in the near vicinity of stone quarry area. Further the comprehensive and detail investigations are required to establish the relationship between quarry dust and abscission pattern.
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