Effects of deficit irrigation and biochar addition on the growth, yield, and quality of tomato

- Study Biochar amendment (BA) effects on tomato grown under deficit irrigation (DI).
- BA significantly enhanced tomato growth, physiology and yield under two DI levels.
- Yields under DI with BA were almost the same as those under full irrigation without BA.
- DI with BA improved irrigation water use efficiency and tomato fruit quality.
- DI can reduce water use by 50%; findings are important to areas with water shortage.

Biochar soil amendments have the potential to improve the soil water and nutrient status, and could enhance crop productivity. A greenhouse experiment was conducted over two consecutive growing seasons to investigate the effects of biochar amendment (BA) in combination with deficit irrigation (DI) on tomato growth, physiology, yield, fruit quality, and irrigation water use efficiency (IWUE). Plants were grown in a ridge and furrow system. A randomized complete block design was used that comprised three irrigation regimes (W1 = 50%, W2 = 75% and W3 = 100% of the reference evapotranspiration) as blocks; each block had nine plots with BA applied at three rates (T1 = 0, T2 = 25, and T3 = 50 t ha−1) in three replications. The BA treatments (T2 and T3) improved soil water storage in both DI treatments (W1 and W2), which consequently enhanced growth, physiology and yield of tomato compared with the control (T1). There was no significant difference (P < 0.05) in yield between the W1-T2 and the W3-T1 treatments, i.e., BA (T2) could reduce water use by 50% without affecting yield. Furthermore, BA significantly increased soil organic matter (SOM) and total nitrogen (TN), while soil nitrate nitrogen and ammonium nitrogen levels were decreased significantly (P < 0.05). DI significantly increased the fruit quality and IWUE compared to the full irrigation regime (W3). The integration of BA along with DI can be considered as a viable approach that improves crop productivity and promotes irrigation water use efficiency (IWUE).