Effects of Bay Leaf (Laurus nobilis L.), Potato (Solanum tuberosum L.) Peel and Banana (Musa Species) Peel Extracts on Bio-Chemical Indicators of Some Upland Rice (Oryza sativa L.) Crop under Higher Iron in Acid Soil Condition

Background: The occurrence of high rainfall in Assam and leaching of base cations cause the soils to become acidic in reaction. The high mobility of iron in acid soil and its absorption raises the iron concentration, and it damages the physiology of crop plants. That is why excessive iron is regarded as one of the limiting factors responsible for lowering growth, development and yield of upland rice crop under irrigation through shallow tube wells. An innovative approach using extracts of potassium- and antioxidant-rich bio-inputs might be a novel approach for deterring and halting physio-biochemical aberrations due to higher iron in acid soil condition. Method: A pot experiment (CRBD with three replications) was carried out to investigate the effects of bay leaf, potato peel, and banana peel extracts on biochemical indicators of some upland (Ahu) rice crop (varieties: Inglongkiri, Dehangi (Fe tolerant), Lachit (Fe susceptible), and Luit) under higher iron in acid soil conditions during the Autumn season (March-September, 2024). The five treatments were: (1) 100 ppm FeSO₄ as basal at vegetative stage (control), (2) 100 ppm FeSO₄ as basal at vegetative stage plus root dip treatment before transplanting and foliar spray with bay leaf extract at 20 days after transplanting, (3) 100 ppm FeSO₄ as basal at vegetative stage plus root dip treatment before transplanting and foliar spray with banana peel extract at 20 days after transplanting, (4) 100 ppm FeSO₄ as basal at vegetative stage plus root dip treatment before transplanting and foliar spray with potato peel extract at 20 days after transplanting; (5) Natural soil without any treatment (absolute control). Result: In general, compared to the control, the treatments significantly increased biochemical indices viz., total chlorophyll (10.80-21.90%), chlorophyll 'a' (6.39-20.93%), chlorophyll 'b' contents (7.27-22.35%) at maximum tillering stage; total chlorophyll (10.96-21.38%), chlorophyll 'a' (11.88-21.89%), chlorophyll 'b' contents at heading stage (7.22-15.79%), NR activity at maximum tillering (12.43-35.52%) and heading (15-36.23%) stages, carbohydrate content (7.51-13.81%) and reduced iron content (10.57-21.34%) in grain at harvest. The bio-input extracts lessened cation leakage at maximum tillering (2.25-1.63%) and heading (3.52-2.83%) stages, and lipid peroxidation at maximum tillering (30.03-10.55%) and heading (29.64-10.96%) stages, despite the presence of high iron in the soil (initial: 200 ppm, harvest: 106 ppm). In the experiment, the intensity of blue colour following Perl's Prussian Blue staining was directly related to iron content in grain, with darker staining indicating higher iron accumulation, and this was altered by the bio-input treatments.