Determination of the effects of soil nitrogen and foliar zinc applications on yield and yield components of sesame crops and on zinc biofortification in grain in second crop sesame cultivation

This study, which aimed to determine the effects of zinc biofortification on the development of sesame plant and its grains, was carried out in 2022 and 2023 in two different sesame fields grown as Wheat-Sesame and Broad Bean-Sesame rotations according to the factorial experimental design in randomized blocks with 4 replications. After wheat and broad bean harvest, different doses of N (0, 3, 6, 9 kg N da-1) from the soil and ZnSO4 (0, 0.15, 0.30, 0.45%) fertilizer were applied from the leaves for zinc biofortification; some analyses were carried out in soil, plant, leaf and grain, and growth parameters, yield and some quality traits in sesame grains were examined. According to the research results, it was determined that N fertilizer applied at different doses from the soil to sesame plants grown in wheat-sesame rotation in 2022 and 2023 had a significant effect on root width and grain yield among some morphological characteristics of the sesame plant, differed in terms of other morphological characteristics according to years, and increased grain protein and grain oil content in both trial years. It was determined that N applications on plant height were obtained from the highest N2 dose application (166.5 cm) in 2022, and in terms of the interaction of N and Zn applications in 2022, the highest plant height value (177.3 cm) was obtained at the N2Zn2 application dose of 6 kg N da-1 and 0.30% ZnSO4 application dose. In different N doses on grain yield in sesame plant, the highest grain yield (13.9 g plant-1) was obtained with N2 (6 kg N da-1) application dose in 2022 and the highest grain yield (15.4 g plant-1) was obtained with N3 (9 kg N da-1) application dose in 2023. In the averages of different Zn doses, Zn0, Zn1 and Zn3 application doses provided the highest values in 2023. In terms of N*Zn interaction in 2023, the highest grain yield value (17.7 g plant-1) was obtained with N3Zn2 application dose of 9 kg N da-1 + 0.30% ZnSO4 application dose. In grain zinc values, the highest values were obtained with N0 and N1 application doses in 2022, and in terms of the effect of Zn applications, the highest (71.69 mg kg-1) zinc value per grain was obtained with Zn3 (% 0.45 ZnSO4) application dose. In terms of the effect of the averages of Zn applications in 2023, the highest (79.08 and 82.72 mg kg-1) zinc values per grain were obtained with Zn2 and Zn3 application doses. In the effect of increasing Zn doses on oil content in grain in 2023, the highest oil content was provided by Zn3 application (55.6%). In the evaluation made in terms of NxZn interaction, N2Zn1 and N2Zn2 applications provided the maximum values (58.0% and 58.2%, respectively) in 2022, while the highest values in oil content in grains were obtained from N2Zn2 and N2Zn3 applications (59.2% and 59.1%, respectively) in 2023. It was determined that N fertilization applied at different doses from the soil to sesame plants grown in the Fava Bean-Sesame rotation in 2022 and 2023 had a significant effect on grain yield and the number of grains in the capsule among some morphological characteristics of the sesame plant, differed according to years in terms of other morphological characteristics, and increased grain protein and grain oil content in both trial years. In 2023, the highest values in N applications on plant height of sesame plants were observed from all N doses except control, while the highest value (26.43 cm) was obtained with N3 (9 kg N da-1) application dose in the first branch height. Maximum values were provided with maximum nitrogen doses in grain yield in both years. In terms of the effect of Zn applications in 2022 and 2023, the highest grain zinc values were provided with Zn2 and Zn3 application doses in grain zinc values. In grain oil content, the highest (% 56.3) oil contents were obtained with N0 application dose in 2022, and the highest (% 53.8) oil contents were obtained with N3 application dose in 2023. In Zn applications at different doses, the highest oil content values were obtained with all applications except Zn0 application dose in 2022, while the highest (% 51.93) value was obtained with Zn2 application dose in 2023. In terms of NxZn interaction, the highest oil content (59.4% and 58.6%, respectively) was obtained with N0Zn2 and N1Zn2 application doses in 2022, and the highest oil content (59.2%) was obtained with N3Zn1 application dose in 2023. As a result of the study, it was determined that nitrogen and zinc applications applied at different doses increased the amount of zinc in sesame grain, had a positive effect on the protein content of sesame and the amount of sesame oil, and also provided significant increases in grain yield. In this context, considering the purpose of the study, it is of great importance to understand the value of sesame grown under farmer conditions due to the minerals, vitamins and antioxidants it contains and to support it with appropriate fertilization programs and biofortification studies. It has been interpreted that the expected effects of rotation systems are not very high, and that this is due to sesame having a short cultivation period and consuming nutrients rather than gaining nitrogen from the soil with the harvest of the pod. In traditional sesame cultivation, which is grown as a second crop, the limited use of fertilizer can negatively affect yield and some quality parameters. In this context, productivity can be increased by taking into account the nitrogen fertilization application dose. In addition, it has been tried to establish the adequacy in grain nutrition, especially in terms of zinc, in this study. Thus, higher economic income can be achieved by achieving more qualified sesame cultivation in terms of both productivity and nutrition.