Determination of the Drought Tolerance in Camellia Sinensis (L) O. Kuntze, using Catechin Levels in Various Clones in Kericho County
Langat, Charles Kipkoech
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The potentiality for use of catechin levels in selection for drought tolerance ability in clones of tea Camellia sinensis (L) O. Kuntze was studied. The study reported herein was carried out in Tea Research Foundation of Kenya (TRFK) between June 2011 and March 2012. Ten clones of tea known to vary in drought tolerance were screened. The experiment was conducted in an open field over three seasons. The treatments were arranged in a completely randomized design and replicated three times. Catechin levels in tea shoots were analyzed and a regression analysis done. The drought tolerant clones namely; SFS150, TRFK 303/577, and susceptible clones; TRFK 6/8, TRFK 12/9, TRFK 301/4, TRFK 31/11, S15/10, TRFK 7/9, TRFK 31/8, and BBK 35 were selected based on physiological data and field performance. Clones were evaluated in three sequential seasons; cold and wet (June-August 2011), warm and wet (October–December 2011) and dry and hot (January–March 2012) under field conditions. A highly positive correlation was observed between an increase in soil moisture deficit and a decrease in catechin contents. During the cold and wet season, the effect of soil water content on catechin level was not clearly expressed. However, significant clone × moisture treatment interactions (p≤ 0.05) were found for all clones during the dry and hot season. Under soil moisture stress, reduced catechin contents were found in all the ten clones. There was substantial clonal variation in response to soil water deficit. During the dry period, the drought-susceptible clones showed a relatively higher decline in catechin levels compared with the drought-tolerant clone. The catechin decreasing effect of water stress was clearly observed in the drought susceptible clones compared to the tolerant ones, suggesting that tolerance to soil moisture stress and accumulation of catechins are strongly correlated. The results indicate that declining soil moisture content (SMC) reduced catechin levels. This technique of analyzing catechin levels may help in skipping the time-consuming field tests. Thus, instead of taking several years to identify a clone that is drought tolerant, the breeder could just analyze catechin levels. Using this biochemical response could act as a substitute for or to assist in phenotypic selection, in a way which may make it more efficient, effective, reliable and cost effective compared to the conventional selection procedures.