Design and optimization of NPK fertilization for ginger (Zingiber officinale) seed rhizome production from tissue-cultured plantlets in soilless culture

This abstract presents a standardized NPK fertilization protocol for producing ginger seed rhizomes from pre-basic seed rhizomes derived from tissue-cultured plantlets. We examined the effects of NPK fertilization in a soilless medium on the cultivation of ‘pre-basic’ to ‘basic' seed rhizomes, providing disease-free planting materials via an L₉(3⁴) orthogonal experimental design. During the early growth phase, N2P1K3 (90 mg l^-1 N + 20 mg l^-1 P + 180 mg l^-1 K) has significantly enhanced photosynthesis and leaf growth, resulting the highest net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, and transpiration rate. K and P significantly regulates the photosynthetic traits, which were associated with increased leaf counts and taller plants, indicators of overall plant vigor. In the late growth stage, N3K2 (300 mg l^-1 N + 400 mg l^-1 K) supported vigorous rhizome development, yielding bulky rhizomes with numerous fingers. Nitrogen significantly influenced tiller number, finger number and overall plant biomass. These findings highlight the importance of a balanced NPK regimen in enhancing the quantity and quality of seed rhizomes. Our technical approach could facilitate the large-scale production of healthy basic seed rhizomes in ginger cultivation.