Affiliation:
1. IoP Collaborative Creation Center, Kochi University, 200 Otsu, Monobe, Nankoku City 783-8502, Kochi, Japan
2. Kochi Agricultural Research Center, 1100 Hataeda, Nankoku City 783-0023, Kochi, Japan
Abstract
This study investigated the performance of four different fertigation scheduling methods in greenhouse-grown, drip-fertigated Chinese chive (Allium tuberosum) cultivation. These methods were based on (1) the use of a timer (control), (2) accumulated radiation (AR), (3) estimated evapotranspiration (ET), and (4) measured soil moisture (SM), with fertilizer application proportional to the supplied water. These methods caused considerable variations in the amount of fertigation water (I), soil volumetric water content (θ), and bulk soil electrical conductivity, leading to variations in the harvested fresh weight (FW). The SM-based method maintained the target θ and achieved the highest irrigation water productivity (WP; the ratio of FW to ΣI), while the ET-based method led to insufficient I and FW loss. The AR-based method over-fertigated, but no FW loss was observed. Compared to the WP of the control, those of the SM-, ET-, and AR-based methods varied by +1%, −14%, and −57%, respectively. Different fertigation methods did not significantly affect leaf photosynthetic capacity, but under-fertigation caused a significant decline in stomatal conductance. Compared to the ET- and AR-based methods, the SM-based method seemed to have a lower risk of under-/over-fertigation because I in the SM-based method could be adjusted according to θ.