Effect of biocar and mulch applications on yield and quality characteristics of tomatoes under limited irrigation conditions

This study examined the effects of different irrigation levels, biochar doses, and mulch applications on the yield, quality, and nutrient content of tomato fruit within the scope of sustainable agricultural practices. The research was conducted at the research field of the Faculty of Agriculture, Isparta University of Applied Sciences. The study included three different irrigation treatments (I100: full irrigation, I75: 25% water deficit, and I50: 50% water deficit), four different biochar doses (B0: 0 t/ha, B1: 10 t/ha, B2: 20 t/ha, and B3: 30 t/ha), and two different mulch applications (M0: without mulch, M1: with mulch). According to the research results, plant water consumption (ET) was highest in M0B3I100 (2191.5 mm) and lowest in M1B0I50 (808.7 mm); water use efficiency (WUE) was highest in M1 (26.2 kg/m3) and lowest in M0 (22.3 kg/m3). Among the experimental treatments, the highest yield was obtained from M0B3I100 (42.86 t/ha), while the lowest yield was recorded in M1B3I50 (15.71 t/ha). Biochar applications increased total yield by 7.99% to 9.44%, while the combined use of mulch and biochar enhanced yield by 0.20% to 12.03%. The results showed that full irrigation (I100) provided the highest yield, but partial water stress (I75 and I50) stimulated the production of secondary metabolites such as lycopene, vitamin C, and flavonoids by increasing metabolic stress in plants. Biochar applications improved soil properties, increased water retention capacity, and significantly enhanced fruit quality; the highest biochar dose (B3) led to notable increases in flavonoid, lycopene, and carotene levels. Mulch applications preserved soil moisture and improved water use efficiency; however, their effects on quality parameters were limited. The interactions among irrigation, biochar, and mulch factors created synergistic effects in enhancing nutrient content and color intensity. These findings highlight the potential of integrating irrigation management, biochar, and mulch applications to promote sustainable resource use and improve tomato production quality.