EFFECTS OF VOLUME AND INITIAL STRENGTH OF MEDIUM ON THE GROWTH, PHOTOSYNTHESIS AND ION UPTAKE OF POTATO (SOLANUM-TUBEROSUM L) PLANTLET IN-VITRO

Single-node stem cuttings each with a leaf of potato (Solanum tuberosu m L. cv. Benimaru) plantlets were cultured in-vitro under photoautotro phic conditions for 24 days on full, half or quarter strength Murashig e and Skoog liquid media (16 or 32 ml per vessel, or 4 or 8 ml per exp lant) in fibrous polyester cubes in 480-ml glass jars. The environment al conditions were 25 +/- 1 degrees C air temperature, 75 similar to 9 2% relative humidity, 1 similar to 2 mmol mol(-1) CO2 in the culture r oom during photoperiod, 16 hr . d(-1) photoperiod, 170 mu mol m(-2). s (-1) photosynthetic photon flux density (PPFD), and number of vessel a ir exchange per hour of 1.4. After 24 days of culture, fresh. and dry weights, shoot length, number of leaves, leaf area, net photosynthetic rate per until; leaf dry weight and relative growth rate per day of t he plantlet were enhanced, while percent dry matter was suppressed, wi th increasing volume and initial strength of the medium. The concentra tion of P in the medium was near zero g.m(-3) on day 24 in all the tre atments. The concentration of P in the medium was near zero g . m(-3) on day 24 in all the treatments. The concentration of NH4 was also nea r zero g . m(-3) except in the full strength with 32-ml medium after 2 4 days of culture. Uptake rate per plantlet gram dry weight of NO3, NH 4, P, K, Ca and Mg over the 24-day period increased with increasing th e volume and initial strength of the medium. Both the volume and initi al strength of the medium, which affect the initial ion content, affec ted the growth, photosynthesis and ion uptake of potato plantlets in v itro over the 24 day period.