1
Bilecik Seyh Edebali University, Faculty of Agricultural and Natural Sciences, Department of Field Crops, Bilecik
Abstract
Drought stress is one of the most critical abiotic factors limiting crop productivity and forage quality worldwide. Sorghum (Sorghum bicolor L.) is an important alternative forage crop with higher drought tolerance compared to maize, making it suitable for semi-arid regions such as south of Turkey. This field experiment, conducted in 2022, investigated the effects of exogenous applications of Zeatin and Brassinolides, applied pre-sowing, post-sowing, and in combination, on the drought tolerance, yield, and forage quality of silage sorghum under Bilecik ecological conditions. Results demonstrated that plant growth regulator (PGR) treatments significantly improved crude protein (CP) content and protein yield, reduced acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents, and enhanced digestibility parameters such as dry matter intake (DMI), digestible dry matter (DDM), relative feed value (RFV), and metabolizable energy (ME). The combined application of 1% Zeatin and 1% Brassinolides, particularly under both pre- and post-sowing conditions, was the most effective treatment, leading to the highest CP content (11.97%), CP yield (293.0 kg da⁻¹), RFV (127.9), and ME (2.28 Mcal/kg DM). These findings highlight the potential of PGRs as a practical strategy to mitigate drought stress, improve forage quality, and sustain livestock production in water-limited environments.
KIZIL AYDEMİR, S. (2025). Role of Plant Growth Regulators in Enhancing Drought Tolerance and Forage Quality of Silage Sorghum. ISPEC Journal of Agricultural Sciences, 9(4), 984–995. https://doi.org/10.5281/zenodo.17245672
📄Adıyaman, C., Erbil, E., Çelik, A., Hatipoğlu, H., Aksoy, M., Acar, M., 2020. İkinci ürün tatlı sorgum (Sorghum bicolor L.) Moench]’un Şanlıurfa koşullarında bazı tarımsal ve teknolojik özelliklerinin belirlenmesi. Iğdır Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 10(4): 3084-3094.
📄Akdeniz, H., Karslı, M., Nursoy, H., Yılmaz, İ., 2002. Determination of the chemical composition and digestible dry matter yields of some grain sorghum varieties matter yields of some grain sorghum varietie. Turkish Journal of Veterinary & Animal Sciences, 27: 1349-1355.
📄Anonymous, 2020. Faostat statistical database. Food and Agriculture Organization of the United Nations, Rome.
📄Anonymous, 2021. Turkish State Meteorological Service. Statistical data for our provinces. https://www.mgm.gov.tr/ver idegerlendirme/il-ve-ilceler-istatistik.aspx (Accessed: 10.02.2022).
📄Baloch, F.S., Altaf, M.T., Liaqat, W., Bedir, M. Nadeem, M.A., Cömertpay, G., Çoban, N., Habyarimana, E., Barutçular, C., Cerit, I., Ludidi, N., Karaköy, T., Aasim, M., Chung, Y.S., Nawaz, M.A., Hatipoğlu, R., Kökten, K., Sun, H.J., 2023. Recent advancements in the breeding of sorghum crop: current status and future strategies for marker-assisted breeding. Frontiers in Genetics, 14: 1150616.
📄Bray, E.A., Balley-Serres, J., Weretilnyk, E., 2000. Responses to abiotic stress. Biochemistry and molecular biology of plants. American Society of Plant Physiologists, Rockville, 1158-1203.
📄Boyer, J.S., 1982. Plant productivity and environment. Science, 218: 443-448.
📄Ebrahimi, M., Rajabian, M., Arzani, A., 2019. Drought tolerance in sorghum: physiological and molecular perspectives. Journal of Plant Physiology, 234: 26-35.
📄Farooq, M., Wahid, A., Kobayashi, N., Fujita, D., Basra, S.M.A., 2012. Plant drought stress: Effects, mechanisms and management. Agronomy for Sustainable Development, 29(1): 185-212.
📄Hasanuzzaman, M., 2019. Brassinosteroids in plant stress tolerance. Agronomy, 9(8): 450. Iddrisu, A.M., Kökten, K., Çaçan, E., 2024. The effect of different irrigation frequency and level on yield and quality characteristics of silage sorghum. Turkish Journal of Agriculture - Food Science and Technology, 12(6): 924-931.
📄Kaçar, B., 1984. Bitki Besleme Uygulama Kılavuzu. Ankara Üniversitesi Ziraat Fakültesi Yayınları, Ankara.
📄Kaplan, M., Arslan, M., Kale, H., Kara, K., Kökten, K., 2017. GT biplot analysis for silage potential, nutritive value, gas and methane production of stay-green grain sorghum shoots. Ciencia e Investigacion Agraria, 44(3): 230-238.
📄Kapluhan, E., 2013. Türkiye’de kuraklık ve kuraklığın tarıma etkisi. Marmara Coğrafya Dergisi, 27: 487-510.
📄Korkmaz, H., Durmaz, A., 2017. Bitkilerin abiyotik stres faktörlerine verdiği cevaplar. Gümüşhane Üniversitesi Fen Bilimleri Dergisi, 7(2): 192-207.
📄Khan, N., Bano, A., Rahman, M.A., 2020. Role of plant growth regulators in improving abiotic stress tolerance. Plant Growth Regulation, 90(2): 157-170.
📄Lesk, C., Rowhani, P., Ramankutty, N., 2016. Influence of extreme weather disasters on global crop production. Nature, 529(7584): 84-87.
📄Li, Y., Ruperao, P., Batley, J., Edwards, D., Khan, T., Colmer, T.D., Pang, J., Siddique, K.H.M., Sutton, T., 2018. Investigating drought tolerance in chickpea using genome-wide association mapping and genomic selection based on whole-genome resequencing data. Frontiers in Plant Science, 9: 190.
📄Mekonnen, M., Taddesse, M., Dessie, T., 2021. Forage potential and adaptability of sorghum-sudangrass hybrids in dryland farming. Tropical Grasslands-Forrajes Tropicales, 9(2): 151-160.
📄Morrison, J.A., 2003. Hay and pasture evaluation. Agricultural Extension Service Bulletin, University of Tennessee, USA.
📄Pantoja-Benavides, A.D., 2022. Foliar cytokinins or brassinosteroids applications influence physiological responses of rice under heat stress. Frontiers in Plant Science, 13: 983276.
📄Peleg, Z., Blumwald, E., 2011. Hormone balance and abiotic stress tolerance in crop plants. Current Opinion in Plant Biology, 14(3): 290-295.
📄Rady, M.M., Varma, C.B., Howladar, S.M., 2021. Common and specialized responses of plant growth regulators against abiotic stresses. Plants, 10(5): 1040.
📄Rakshit, S., Hariprasanna, K., Gomashe, S., Ganapathy, K.N., Das, I.K., Ramana, O.V., Dhandapani, A., Patil, J.V., 2014. Advances in sorghum breeding research in India. Tropical Plant Biology, 7(1): 5-14.
📄Rhaman, M., Imran, S., Rauf, F., Khatun, M., Baskin, C., Murata, Y., Hasanuzzaman, M., 2020. Seed priming with phytohormones: An effective approach for the mitigation of abiotic stress. Plants, 10: 37.
📄Ribeiro, D.M., Santos, S.D.N.B., Ferreira, D.C.D.S., Miranda, J.F.F.D., Oliveira, J.T.D., Cunha, F.F.D., Velloso, C.L.A.D.P., Silva, P.A., Oliveira Neto, C.F.D., 2025. Effect of 24-epibrassinolide plant hormone rates on the level of macronutrients in forage sorghum plants subjected to water deficit and rehydration. Grasses, 4(3): 33.
📄Rohweder, D.A., Barnes, R.F., Jorgensen, N., 1978. Proposed hay grading standards based on laboratory analyses for evaluating quality. Journal of Animal Science, 47(3): 747-759.
📄SAS Institute, 1999. SAS/STAT user’s guide, version 8. Cary, NC: SAS Institute Inc.
📄Sahoo, S., Saha, B., Awasthi, J.P., Omisun, T., Borgohain, P., Hussain, S., Panigrahi, J., Kumar Panda, S., 2019. Physiological introspection into differential drought tolerance in rice cultivars of North East India. Acta Physiologiae Plantarum, 41: 53.
📄Şimşek Soysal, A., Demirkol, G., Önal, Ö., Kaşko Arıcı, Y., Acar, Z., Yılmaz, N., 2018. Tuz stresinin sorgum-sudanotu melezi çimlenme ve fide gelişim özelliklerine etkisi. Uluslararası Tarım ve Yaban Hayatı Bilimleri Dergisi, 4(2): 274-252.
📄Taiz, L., Zelger, E., Moller, I.M., Murphy, A., 2015. Plant Physiology and Development. 6th Edition, Sinaur Associates, Sunderland, CT.
📄Tutar, H., Kökten, K., Eren, Ö., 2024. Determination of environmental impacts using life cycle assessment of plants grown for bioenergy: example of sorghum x sudan grass hybrid. Journal of Agricultural Sciences, 30(2): 263-272.
📄Wahid, A., Farooq, M., Hussain, M., 2020. Improving drought tolerance in forage crops: Insights into physiological and molecular approaches. Frontiers in Plant Science, 11: 570.
📄Wang, X., Zhang, X., Chen, J., Wang, X., Cai, J., Zhou, Q., Dai, T., Cao, W., Jiang, D., 2018. Parental drought-priming enhances tolerance to post-anthesis drought in offspring of wheat. Frontiers in Plant Science, 9: 261.
📄Van Soest, P.J., Robertson, J.D., Lewis, B.A., 1991. Methods for dietary fibre, neutral detergent fibre and non-starch polysaccharides in relation to animal nutrition. Journal of Dairy Science, 74: 3583-3597.
📄Yavaş, İ., Akgül, H., Ünay, A., 2016. Bitkilerin kuraklığa dayanıklılığını artırmaya yönelik uygulamalar. Türk Tarım-Gıda Bilim ve Teknoloji Dergisi, 4(1): 48-57.
📄Yücel, C., Hatipoğlu, R., Dweikat, İ.M., İnal, İ., Gündel, F., Yucel, H., 2018. Farklı tatlı sorgum (Sorghum bicolor var. Saccharatum L.) Mohlenbr.) genotiplerinin Çukurova ve GAP bölgelerinde biyo-etanol üretimpotansiyellerinin saptanması. Tübitak (1003) 114O945 Nolu Proje Sonuç Raporu, 302s.
