Sensitivity and responses of sorghum hybrid lines to wheat aphid (Sitobion avenae Fabricius) infestation

Sorghum bicolor (L.) Moench is a resilient cereal crop that thrives in arid conditions and produces substantial yields following periods of drought. However, sorghum crop productivity is threatened by insect pests, such as Sitobion avenae Fabricius, a common aphid species on sorghum. The research included seven sorghum hybrid lines between 2021 and 2023. The study aimed to evaluate the cyanogenic glycoside content in these lines, their sensitivity to aphid infestation, and the effect of S. avenae attack on the integrity of plastid pigments and the alteration of leaf chlorophyll fluorescence parameters. Aphid infestation occurred under natural field conditions. The study revealed the classified very low-sensitive hybrids (L №305 and Whiteseed) exhibited a significantly lower density of S. avenae, attributable to a substantially more elevated concentration of cyanogenic glycosides in non-infested plants and a significant decrease in glycosides in infested plants. Changes in carotenoid and chlorophyll contents and chlorophyll fluorescence parameters in infested hybrids showed a slight reduction. This led to a stronger protective and antibiotic effect on the host plants and weaker aphid performance. The medium-sensitive hybrids (L №302 and L №256) exhibited a significantly higher aphid density because of a lower cyanogenic glycoside content in non-infested hybrids and a considerably more violent decrease in glycosides in infested hybrids. Aphid infestation resulted in a considerable reduction in chlorophyll and carotenoid levels and a pronounced decrease in photosynthetic parameters. This showed the sensitive plants' stress response to aphid invasion. The study's findings enhance the understanding of how aphid infestation levels impact sorghum plants. This understanding is essential for identifying and selecting resistant sorghum varieties. These traits are pivotal in determining crop yield, thus serving as crucial indicators for future research endeavours concerning aphid resistance in sorghum.