Effect of carboxymethyl cellulose and gibberellic acid-enriched biochar on osmotic stress tolerance in cotton.

The deleterious impact of osmotic stress, induced by water deficit in arid and semi-arid regions, poses a formidable challenge to cotton production. To protect cotton farming in dry areas, it's crucial to create strong plans to increase soil water and reduce stress on plants. The carboxymethyl cellulose (CMC), gibberellic acid (GA) and biochar (BC) are individually found effective in mitigating osmotic stress. However, combine effect of CMC and GA with biochar on drought mitigation is still not studied in depth. The present study was carried out using a combination of GA and CMC with BC as amendments on cotton plants subjected to osmotic stress levels of 70 (70 OS) and 40 (40 OS). There were five treatment groups, namely: control (0% CMC-BC and 0% GA-BC), 0.4%CMC-BC, 0.4%GA-BC, 0.8%CMC-BC, and 0.8%GA-BC. Each treatment was replicated five times with a completely randomized design (CRD). The results revealed that 0.8 GA-BC led to increase in cotton shoot fresh weight (99.95%), shoot dry weight (95.70%), root fresh weight (73.13%), and root dry weight (95.74%) compared to the control group under osmotic stress. There was a significant enhancement in cotton chlorophyll a (23.77%), chlorophyll b (70.44%), and total chlorophyll (35.44%), the photosynthetic rate (90.77%), transpiration rate (174.44%), and internal CO concentration (57.99%) compared to the control group under the 40 OS stress. Thus 0.8GA-BC can be potential amendment for reducing osmotic stress in cotton cultivation, enhancing agricultural resilience and productivity.