Muskmelon morpho-physiology and yield: The combined effect of biostimulants and phosphorus

Muskmelon (Cucumis melo L.), a hydrating fruit rich in antioxidants, vitamins, and minerals, is widely grown in tropical and subtropical regions where phosphorus (P) deficiency is common. P availability influences sugar and acid contents in melons because of its role in sugar acid phosphatase enzymes. Increasing phosphorus use efficiency through the use of biostimulants, particularly phosphorus-solubilizing bacteria, represents a promising approach for sustainable muskmelon production. These biostimulants solubilize inorganic P by releasing phosphatase enzymes and organic acids. This study examined the effects of three P levels (100%, 50%, and 0% P₂O₅) and biostimulants (control, GEA 1499- a formulation containing plant base biostimulant and the microbial species Bacillus pumilus and Bacillus megaterium at 2.5 kg ha-1, and GEA 1499 at 5 kg ha-1) on muskmelon morphology, physiology, biochemistry, and yield. The combination of 100% P₂O₅ with GEA 1499 at 2.5 kg ha-1 significantly improved the leaf count, vine length, photosynthesis, stomatal conductance, transpiration, chlorophyll index, marketable yield, and total soluble solids while reducing the undesirable traits rind thickness and seed cavity dimensions, indicating improvement in fruit quality. Phosphorus enhances gas exchange via ATP and the Calvin cycle, whereas biostimulants containing microbes and plant extracts improve nutrient availability, promoting better muskmelon growth, yield, and fruit quality. A combination of plant extracts provides phytohormones that complement the microbial action and improve the overall efficiency of the biostimulant.