| Summary: | Magnesium (Mg) is the most commonly deficient nutrient in tropical banana-growing areas. The effects of different concentrations of Mg on morpho-physiological and biochemical responses on three commercial cultivars (Baxi, Haigong, and Guangfen No.1) of bananas were accessed for 12 weeks. Results showed genotypic variation in the utilization and tolerance to different Mg levels. The optimum Mg level was 1 mM for Baxi and Guangfen No.1 and 3 mM for Haigong. Both the deficiency and excess of Mg caused a severe reduction in plant height, dry weight, total root length, and root surface area of Haigong and Baxi. Mg stress reduced root growth by impairing photosynthate translocation and increased carbohydrate contents in the source leaf. Under Mg stress, more reduction in photosynthetic pigment and photosynthesis rate, higher accumulation of carbohydrates and malondialdehyde contents, and higher activities of antioxidative enzymes were observed in Haigong as compared to other genotypes. Based on the above results, it is concluded that Haigong is most sensitive to Mg stress while Guangfen No. 1 was least affected and tolerant to changes in the Mg levels.
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