Estimation of Evapotranspiration and Crop Coefficient of Rain-Fed Tea Plants under a Subtropical Climate
2021
Shenghong Zheng | Kang Ni | Lingfei Ji | Chenguang Zhao | Hongling Chai | Xiaoyun Yi | Weizhong He | Jianyun Ruan
Crop coefficient (K<sub>c</sub>) is one of the most significant parameters for crop water demand prediction and irrigation scheduling. However, there is a lack of knowledge about water vapor and K<sub>c</sub> in tea plantation ecosystems. This study explored and determined the actual evapotranspiration (ET<sub>c</sub>) and K<sub>c</sub> of two cultivars of tea (<i>Camellia sinensis</i>), clone variety Baiye1 (BY1) and Longjing43 (LJ43), based on lysimeter data. An estimation was made for both for ET<sub>c</sub> and adjusted ET<sub>c</sub>, and the corresponding K<sub>c</sub> and adjusted K<sub>c</sub>. The results showed that the adjusted ET<sub>c</sub> and K<sub>c</sub> values revealed a minor fluctuation when compared to the ET<sub>c</sub> and K<sub>c</sub> values during the experimental period, which indicated that the adjusted ET<sub>c</sub> and K<sub>c</sub> values were more precise and practical to field conditions. The average adjusted K<sub>c</sub> values were 0.71 (range of 0.43–1.02) for BY1 and 0.84 (range of 0.48–1.22) for LJ43. Additionally, heavy pruning can decrease ET<sub>c</sub> and K<sub>c</sub> values, possibly due to the lower level of LAI after pruning. Moreover, it is clearly manifested that BY1 consistently had lower ET<sub>c</sub> and K<sub>c</sub> values than those of LJ43 because of plant growth status differences between BY1 and LJ43. Overall, our study proposed a reliable reference of K<sub>c</sub> in tea plantation, and illuminated the effects of pruning and plant growth differences on K<sub>c</sub>, which could provide a strong basis for precise irrigation in tea plantations in a subtropical climate.
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