Conclusion

 

From our study, it can be seen that both tannic acid and green tea were effective against P. carotovorum. Both substances showed greater inhibition towards actively dividing cells in the logarithmic phase of growth, as could be seen from the colony count results, as compared to cells in the stationary phase of growth that infected a host plant. In other words, tannic acid and green tea were likely to be bacteriostatic in nature, inhibiting the reproduction of bacteria, rather than showing a bactericidal effect. Nevertheless, there is still a good potential of using both tannic acid and green tea in overcoming the problem of soft rot in plants.

 

Past research and experiments conducted have discovered several ways to control bacterial soft rot. In 2006, scientists discovered a bacteriocin-like substance which inhibited bacterial soft rot caused by Erwinia carotovorum in potato tubers via the lysis of the bacteria (Cladera-Olivera, Caron, Motta, Souto and Brandelli, 2006). The use of chemicals such as chlorine, bleach and citric acid also showed more than 90% reduction in potential for bacterial soft rot (Bartz and Kelman, 1986). However, the inhibitors used were either hard to mass-produce to meet the needs of the agriculture industry, or were chemicals that could pose harm to consumers and the environment. Our study used two easily obtainable and environmentally-friendly substances, which could be useful in increasing crop yield.

 

Limitations

 

One of the limitations was the varying thickness of lettuce pieces that could possibly affect the time for the formation of soft rot. This was overcome by selecting pieces that had approximately similar thickness. Furthermore, the method of application of tannic acid and green tea to plants cannot be utilised in large-scale applications. The development of aerosols of these agents and direct spraying on plants would be more feasible in large-scale applications.

 

Sustainability

 

The use of natural substances which are inexpensive in reducing incidence of soft rot in plants has important implications. It increases crop yield and ensures sustainability in the production of food crops. Environmental protection is achieved when the use of non-biodegradable, chemical substances which may pollute the environment is reduced. This also leads to sustainable development.           

 

Future Work

 

For further work, spent green tea can be used to determine the effectiveness in the inhibition of soft rot bacterium. Moreover, fruit peels that contain tannic acid may be used instead of pure tannic acid, further reducing the cost.  Finally, other methods of applications such as spraying can be explored.