Browsing by Author "Jayasundara, J.M.M.Y.B."

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    Impact of Rainfall Variation on Tea (Camellia sinensis L.) Yield in Uva Medium Region
    (Uva Wellassa University of Sri Lanka, 2013) Jayasundara, J.M.M.Y.B.; Gunathilaka, R.P.D.; Karunaratne, G.U.
    Tea has been main stay of Sri Lanka’s economy for more than a century and still continues to occupy an important place. Different clmatic parameters affect on tea yield in various degrees. But rainfall pattern (length of dry and wet seasons) and temperature are two key factors affect on the variability of tea production. Generally 2500-3000 mm of annual rainfall is optimum while 1200 mm minimum. Minimum monthly rainfall requirement is quoted as 50 mm (Watson and Zoysa, 2008). Tea yield that declined due to lack of rainfall is about 29-81kg month of rainfall deficit below the optimum rainfall (Wijeratne et al., 2007). Uva is one of the major tea planting area in Sri Lanka and famous for exotically aromatic flavor (Anonymous, 2000).This region is vulnerable to climate changes and it reported highest negative yield change in past year (Sarath and Abeysinghe, 2012). Therefore this study was amied at quantifying the impact of rainfall variation and determine the optimum rainfall level on tea yield. Eighteen estates are located in the Uva medium region and those estates belong to five agro ecological zones (AEZ). Sample was based on tea land extent of different agro ecological zones and accessibility. Two estates from IM1a, One estate from IM2b and Five estates from IU3c were selected. Data were collected for past ten year period (2003 - 2012) and monthly variations in following parameters like Production (yield) , yield productivity (Kg per month), Made yield tea (Kg per month), Yield (Made tea kg ha month), Climate data and Rainfall (mm) were considered. Rainfall data and production data were collected from estate records. Averaged yield values were derived for agro ecological regions where there were data for more than one estate. Quantification of rainfall variation on tea yield was done by using quadratic regression analysis and highly vulnerable area was identified by assiuming 10mm deviation from optimum rainfall level.Analysis was conducted separately for each agro ecological zone.