Physiological indicators and yield of the Chinese cabbage cultivated at different soil water tensions
Federal University of Technology - Paraná, Campus Dois Vizinhos, Faculty of Agronomia, Department of Agronomy, Street adress Estrada para Boa Esperança, km 04, postal code 157, Dois Vizinhos, Paraná, Brazil
The development and yield of Chinese cabbage is influenced by soil moisture. The objective of this study was to evaluate the physiological indicators, development, and yield of Chinese cabbage (Brassica rapa subsp. pekinensis (Lour.) Rupr.) grown at different soil water tension ranges. Two experiments were conducted (2016–2017) in the Olericulture Sector of the Federal University of Technology of Paraná. Two cultivars of the Chinese cabbage, Eikoo and Kinjitsu, and four soil water tension ranges 13–17, 23–27, 33–37, and 43–47 kPa were studied. Eikoo presented higher relative chlorophyll index, photosynthesis, and fresh leaf mass than did Kinjitsu. Physiological indicators transpiration (5.8 mmol H2O m-2 s-1), photosynthesis (14.5 μmol CO2 m-2 s-1), stomatal conductance (0.31 mol H2O m-2 s-1), and WUE (39.4 kg m-3) were higher at 13–17 kPa soil water tension. Soil water tension ranges with high water restrictions reduced the fresh leaf mass of both cultivars. Fresh leaf mass decreased by 236.2 and 191.7 g plant-1 in the highest soil water tension range in 2016 and 2017, respectively, when compared with the fresh leaf mass at the 13–17 kPa tension range. The lowest water consumption was observed at the 13–17 kPa tension range. The year 2017 resulted in higher internal CO2 concentration, transpiration rate, fresh leaf mass, number of irrigations and water consumption compared to the year 2016. Thus, the irrigation regime for the most optimal Chinese cabbage cultivation should maintain the soil water tension range at 13–17 kPa.