Seasonal Variations in Chlorophyll content and chlorophyllase activity in Bangla and Mitha varieties of Betelvine (Piper betle L.) grown in different soil treatments
By M. Roy Chowdhury and J.K Johri
February 2003
The Authors are Research Scientists at the Indian Institute of Technology (IIT-KGP) in Kharagpur and at the National Botanical Research Institute (NBRI) in Lucknow, India. They are involved in the development of production technologies for new plant sources of commercial importance. The major R&D programmes at these institutions relate to plant biotechnology, floriculture, tree biology, plant wealth utilization, environmental sciences and taxonomy & ethnobotany.
Seasonal variations in chlorophyll content and chlorophyllase activity were studied in Bangla and Mitha varieties of betelvine, (Piper betle L.) from January to December 2000. During winter environmental conditions enhanced chlorophyll content. The summer and rainy seasons were periods of seasonal stress, characterized by increased chlorophyllase activity. Experimental findings showed that the leaves of the Bangla variety showed a higher chlorophyll content in comparison to Mitha variety. Chlorophyllase activity was on the other hand higher in Mitha variety in comparison to Bangla variety.
Introduction
Seasonal cycles of temperature, day lengths, rainfall, humidity and wind exert a pronounced control over the physiological and reproductive processes in plants. Seasonal environmental patterns of temperature, day length, humidity etc provide plants with a pattern to which developmental changes are «physiologically locked». The aim of this work was to study the physiological response of an important crop plant Piper betle L. to seasonal environmental stress which could also provide information about how crops affected in less than optimum growing conditions. This could further enable to improve the ability of crop plants to cope with seasonal environmental stress (unfavorable seasons) and improve productivity known to be inhibited by environmental factors.
Experimental Setup
The work was carried out in the experimental garden of National Botanical Research Institute Lucknow India under natural environmental conditions. The seasons under study were April - September (Summer) and October- March (Winter). Cuttings were grown in pots 8´ having 10 kg soil (Alluvial and Laterite soil were used) with different ameliorants. (Figure 1, Figure 2). The experiment was done taking three replications for each soil treatment. For all experiments the third leaf was selected to maintain the uniformity of estimations.
Chlorophyll was measured according to Arnon², estimation of chlorophyllase activity was by the method of Ardao and Vennesland ¹ and Holden³.
Results and Discussion
The duration of the experimental period was from January to December 2000 - a period characterized by considerable changes in temperature, photoperiod, light intensity, relative humidity and rainfall.
The temperature ranged between 38.9° C in summer to 10.4° C in winter. The photoperiod ranged from a summer maximum of 14.4 hours to a winter minimum of 9 hours. Light intensity varied from 69,000 lux in summer to 20,000 lux in winter. Relative humidity ranged from 84% during rainy months to 58.2% in summer month Our experimental results indicate that chlorophyll content both chlorophyll a and chlorophyll b and therefore the total chlorophyll is higher in the winter season and successively lowered in summer season. It was also observed that levels of chlorophyll were higher in Bangla variety in comparison to Mitha variety (Fig1). An increase in the activity of Chlorophyllase enzyme (responsible for enzymatic breakdown of chlorophyll by removing the phytol side chain) was reduced in winter season in comparison to summer season (Fig 2). It was observed that an increase in chlorophyllase activity always resulted in the lowering of chlorophyll content and vice versa (Fig 1, Fig 2). Experimental observations also revealed that chlorophyllase activity was greater in Mitha variety (Fig2). A higher activity of this enzyme ultimately leads to the reduced rate of photosynthesis resulting in poor growth and yield during periods of environmental stress.
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Figure 1-A Total chlorophyll in Bangla Leaves (Oct-March)
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Figure 1-B Total chlorophyll in Bangla Leaves (April-Sept)
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Figure 1-C Total chlorophyll in Mitha Leaves (Oct-March)
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Figure 1-D Total chlorophyll in Mitha Leaves (April-Sept)
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Figure 2-A Chlorophyllase activity in Bangla Leaves (Oct-March)
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Figure 2-B Chlorophyllase activity in Bangla Leaves (April-Sept)
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Figure 2-C Chlorophyllase activity in Mitha Leaves (Oct-March)
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Figure 2-D Chlorophyllase activity in Mitha Leaves (April-Sept)
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Acknowledgements
Authors are thankful to the Director NBRI for providing the necessary facilities.
References
- C. Ardao and B. Vennesland, Plant Physiol, 35, 368 (1960)
- D.I. Arnon Plant Physiol, 24 (1949)
- M. Holden, J Biochem, 78, 359 (1961)
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