Drip Irrigation, an Effective Method to Improve the Quantitative and Qualitative Characteristics of Tea Green Leaves in Water Stress Conditions

The aim of this study was to investigate the effect of different levels of drip irrigation treatment on yield, yield components and quality of green tea leaves during drought. This research was conducted for the first time during 2017 and 2018 in the tea garden in Bazkiagorab area of ​​Lahijan in Gilan province. The experiment was performed as split plots in a randomized complete block design with three replications. Irrigation treatment considered was consisted of five levels of 0, 25, 50, 75 and 100% of irrigation needs. Drip irrigation program in the period of water stress was carried out twice a week based on monitoring soil moisture at the depth of root development. Full irrigation of 2225 and 1610 m3/ha in two successive years of experiment caused the production of harvestable shoots in summer to increase by 162 and 153%, respectively, compared with the area without irrigation. Increased water stress at incomplete irrigation levels led to an increase in solids (woodiness) of tea shoots. Conversely, as the amount of irrigation water in the drip irrigation system increased, the weight of the shoots increased. The biennial average of the highest yield of green tea leaves was equal to 9125 kg/ha with 100% irrigation requirement and the lowest yield of 3468 kg/ha was obtained from the area without irrigation. Improvement of tea quality characteristics such as total polyphenols, caffeine, total ash and nitrogen percentage of shoots was also observed by complete irrigation in the drip system.