Abstract

Productivity relates to the ability of photosynthesis. Therefore, the process of photosynthesis is important to promote growth, development and yield. There are many varieties of superior and local cassava (Manihot esculenta Crantz) in Indonesia either unknown of their photosynthesis character. The study aims to investigate the characteristics of photosynthesis and influences of physiological parameters associated the activity of photosynthesis in cassava plants. A study was conducted on Inceptisol soils at UGM research at altitude 113 m above mean sea level between January and November 2014. The treatment of single factor is cassava varieties consist of Adira-4, Malang-6, UJ-5, Singgah and Ketan arranged in a randomized block design with three replications. Cuttings size ±20 cm are planted upright with a distance of 1 m × 1 m (population of 10,000 plants ha^-1). After six months, observation has been done of characters and physiological activities at 10 samples per plots and per varieties. The results showed that there are differences in the density of stomata, stomata aperture width, water content, chlorophyll content and photosynthesis rate between varieties of cassava. Singgah varieties have the Ksd highest with medium Lbs and varieties local of Ketan lowest Ksd. The group of superior varieties of cassava have Kkt medium, but varieties of Malang-6 have Kkt slightly higher and the highest rate of photosynthesis. Singgah varieties have lowest leaves Kkt and medium rate of photosynthesis. Local varieties of Ketan have the highest Kkt and lowest rate of photosynthesis. Group cassava superior varieties had higher photosynthesis rate than the local varieties, local varieties Singgah has a moderate rate and higher than Ketan. Stomata density and the concentration of CO₂ correlated positively and significantly affect the rate of photosynthesis while transpiration increase conductivity stomatal but negatively correlated to the rate of photosynthesis.

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