Determining physiological characteristics of sorghum accessions under drought conditions

Drought is one of the most devastating environmental stresses that significantly affect global agricultural production. Exploring and utilizing drought-resistant crops such as sorghum is crucial to compensate for yield losses caused by drought and ensure global food security. In this regard, a two-year experiment was conducted at the Mediterranean Agricultural Research Institute, Turkey, during 2022 and 2023. A total of 125 grain sorghum accessions, along with 6 commercial hybrids, were studied under full irrigation (100% field capacity) and deficit irrigation (50% field capacity). The experiment was laid out according to an augmented design. The results showed considerable variation in morpho-physiological and yield traits, such as plant height, grains per panicle, SPAD, stomatal conductance, canopy temperature, and NDVI. Traits such as tillers per plant, panicles per plant, panicle length, grain yield, and biological yield were similar under both deficit and full irrigation across both years, indicating that deficit irrigation does not significantly affect these traits. Under both full and deficit irrigation, grains per panicle showed a positive correlation with grain yield across both years. Similarly, SPAD (chlorophyll content) showed a positive correlation with stay green. Furthermore, 37 accessions (identified as ANZ_2, ANZ_10, ANZ_15, ANZ_17, ANZ_34, ANZ_39, ANZ_51, ANZ_58, ANZ_62, ANZ_84, ANZ_91, ANZ_105, ANZ_109, ANZ_112, ANZ_115, ANZ_123, ANZ_136, ANZ_156, ANZ_171, ANZ_180, ANZ_183, ANZ_191, ANZ_194, ANZ_195, ANZ_198, ANZ_199, ANZ_215, ANZ_218, ANZ_220, ANZ_225, ANZ_246, ANZ_343, ANZ_347 ANZ_351, ANZ_372, ANZ_418, ANZ_424) exhibited superior performance under deficit irrigation compared to full irrigation across both years, particularly in terms of grain yield. Cluster analysis revealed that most of these identified accessions clustered together, thereby confirming their consistently enhanced grain yield under deficit irrigation conditions over the two-year period. These accessions exhibit significant potential for drought tolerance and are thus prime candidates for incorporation into breeding programs focused on developing drought-resistant sorghum varieties. This experiment highlights the variability and adaptability of sorghum accessions to different irrigation treatments, offering valuable insights for future breeding and cultivation strategies. Keywords: Sorghum, Deficit irrigation, Stay green, Grain yield, Stomatal conductance