Arbuscular mycorrhizal symbiosis alters morphological and biochemical indices in hot pepper (Capsicum annuum L.) under drought stress

Dr. M. S. R. Krishna


Introduction: Plants are persistently exposed to series of varied unfavorable conditions in natural environments. Around the world, drought is one of the major concerns negatively effecting crop yield. Decreased soil water availability has become more prevalent in several parts of the world limiting arable land for agriculture. Enhancement of drought tolerance in plants mediated by arbuscular mycorrhizal fungi (AMF) is one of the notable strategies that could be persuaded to achieve sustainable agriculture. Capsicum annuum is one of the important horticultural crops. Shallow roots render the crop more prone to water stress. This study was performed to evaluate the impact of AMF on four hot pepper cultivars in pot culture. Materials and Methods: Four cultivars of hot pepper plantlets, namely US-341, VNR-314, VNR-145, and Indam-05 were subjected to three water regimes - control (100% field capacity [FC]), moderate stress (60% FC), and severe stress (40% FC) and five treatments - control, 60% FC with AMF, 60% FC without AMF, 40% FC with AMF, and 40% FC without AMF. Plant growth attributes, namely shoot fresh weight, shoot dry weight, root fresh weight, and root dry mass were measured. Biochemical traits such as relative water content, chlorophyll content, chlorophyll stability index, and ion leakage were quantified. Results: The applied drought stress levels reduced plant growth (shoot biomass and root biomass) of mycorrhizal and non-mycorrhizal plants in comparison to control plants (100% FC). However, the association of mycorrhizal fungus with the plant stimulated growth by increasing the absorption of water from roots and maintaining the same in leaves comparing to AMF non-treated plants. Furthermore, mycorrhizal symbiosis allowed the plants to maintain membrane integrity, thereby reducing the deleterious effects of drought. Drought-stressed mycorrhizal plants showed significantly better performance than non-mycorrhizal plants. Besides, four pepper cultivars responded differently to same AMF emphasizing specific varietal sensitivity to AMF. Among the four cultivars used for the study, VNR-145 showed better performance in both mycorrhizal and non-mycorrhizal treatments. Conclusion: The results highlight that AMF alleviate drought by maintaining relatively higher water status in hot pepper plants. Furthermore, the association of Glomus coronatum AMF and C. annuum var. VNR-145 ecotype is advocated to determine the extent to which these results can be manifold under field conditions.

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