Studies On Physiochemical Mechanism Of Tieguanyin Tea (Camellia Sinensis L.O.Kuntze) Under Different Irrigating

Tea(Camellia sinensis L.O.Kuntze)is the most popular economic crop in Fujian,and Anxi Tieguanyin is a famous brand of Oolong tea in China.But Most of tea plants is grown under rain fed conditions,which might limit tea production by the season drought.Therefore,how to improve the yield stability under seasonal drought conditions is the one of the most important research programs in Fujian.In this paper,2-year Tieguanyin tea plants at the mountain area were treated with 6 different irrigating treatments,5kg water per plant per 5d(T1),10d(T2),15d(T3), 20d(T4),25d(T5)and control(No irrigation).The effects on Tieguanyin tea plants under different irrigating treatments were investgated,and the irrigating methods which was favorable for Tieguanyin plants would be concluded.The results showed that:1.With the increase of irrigating interval,leaf water potential of tea plants decreased.Under 6 different irrigation regime treatment,leaf water potential of tea plants were - 1.81,- 1.92,-2.05,-2.90,-3.03 and -3.20MPa,respectively.The decrease of leaf water potential induced MDA,O₂^- and H₂O₂ accumulated in the leaves,which were highest,9.72,2.58 and 2.29μmol.g^-1FW,under Control.Meanwhile,SOD and POD activity increased at first and then decreased significantly,CAT activity decreased obviously.This disordered protective enzymes SYstem in leaves of Tieguanyin tea plants,then increased the permeability of cytoplasmamembrane and the content of membrane lipid peroxidation.2.With the increase of irrigating interval,photosynthetic mechanism of 2-year Tieguanyin leaves was changed.The content of chlorophyll in the leaves of 2-year Tieguanyin tea plants decreased.At T2,Pn reached its highest,15.55μmol.m^-2.s^-1,but decreased from T3,while Tr and Gs increased at first and then decreased.Fv/Fm and Fv/Fo were highest at T2,which were 0.856 and 5.93,respectively,and then decreased.Therefore,Fv/Fm and Fv/Fo could be considered as references for the irrigating management for Tieguanyin tea plants.Meanwhile,Fo decreased with the increase of irrigation interval,which might be induced by the decrease of chlorophyll content,indicating that the low water stresses were help to dissipate of excess light energy and protect photosynthetic tissue of tea plants.Fo increasing at Control demonstrated that PSâ…¡reaction center was destroyed by drought stress.The highestâ–³Fv,â–³Fv/Ft andâ–³Fv/Fo in the leaves were also found at T2 or T3 treatment.3.The different watering regime also affected the Endogenous Hormone content in the leaves of 2-year Tieguanyin plants.IAA content increased at first,higest, 1803.04ng.g^-1,at T3 and then decreased significantly.While the content of ZR and GA decreased,which were 237.99å’Œ191.58ng.g^-1under Control treatment,respectively. But ABA content increased significantly.With leaf water potential decrease,the ratio of the three promoted Endogenous Hormone to ABA decreased.And IAAO activity increased at first and then decreased,which was correlative significantly with the changes of IAA content.The result showed that Endogenous Hormone content in 2-year Tieguanyin leaves was very sensitive to watering treatments.4.The quality of 2-year Tieguanyin tea plants decreased with the increase of irrigating interval.The content of tea polyphenol was higher,16.31%,under T2 treatment and then became lower with the leaf water potential decrease,while free amino acid was highest under T1 treatment,caffein at Control treatment.In conclusion,irrigating methods of 5kg water per plant per 10d,which maintained the leaf water potential at -1.92MPa,was favorable for Tieguanyin tea plant growing.