抄録
Photosynthesis and dry matter production were examined to understand the growth response of sago palms to different nutrient levels. Seedlings were grown in the pots filled with soil with Kimura B culture solution at 100% (standard), 50%, and 10% strengths for 51 weeks. The total dry matter weight, total leaf area, chlorophyll content per unit leaf area, electron transport rate, N content per unit leaf area, petiole N concentration, and P content per unit leaf area were highest at 100% strength, followed by 50% and 10% strengths. The single leaflet area, and effective quantum yield of photosystem II [Y (II)] (at some light levels) were the highest at 100% strength, and their differences between the 50% and 10% strengths were not significant. The total leaflet number per leaf, emerged leaf number, and net photosynthetic rate were at the same level at the 100% and 50% strengths, the values of which were high as compared with those at the 10% strength. Sago palm growth was influenced by the supply of nutrients for about one year, and among three major elements, nitrogen was found to be the most influential. Phosphorus absorption and translocation were also affected, while K absorption and translocation were not restricted by a reduction in the application of nutrients. The restriction of nutrient supply proceeded with leaf morphogenesis such as leaflet area expansion and photochemical reaction process prior to the depression of new leaf formation and leaf gas exchange.
