Photosynthesis of Sago Palm (Metroxylon sagu Rottb.) Seedling at Different Air Temperatures

Abstract

Photosynthetic activities of the sago palm (Metroxylon sagu Rottb.) were studied to find out its sensitivity to changes in ambient air temperature. The minimum ambient air temperature designed for the experiment was 25-29 • C, while the higher end was 29-33 • C. Several photosynthetic parameters were studied to support our analysis in sago photosynthetic activity, including diurnal leaf gas exchange, assimilation rate vs. CO 2 concentration, leaf greenness, leaf chlorophyll content, and photosynthetic rate vs. irradiance. We found that sago palm photosynthetic activity tends to be more sensitive to minimum than to maximum ambient air temperature. The plants exposed to higher air temperatures had dark green leaf color associated with higher rates of diurnal photosynthesis, chlorophyll content, and rubisco limited photosynthetic activity. They also exhibited higher trend in optimum irradiance absorption level. Consequently, maximum light energy dissipation occurred at higher temperatures.

The spatial distribution of sago palm landscape Sentani watershed in Jayapura District, Papua Province, Indonesia

“…According to Matanubun (2015) in Papua province, the studied plant generally grows in Climate Type B1 that has an average rainfall of 2,118 mm yr -1 . The pattern of rainfall in the Jayapura District shows that the value increases in line with area elevation, hence certain parameters of climate including rainfall and temperature are basic environmental factors contributing to vegetation dynamic (Zhu et al 2016;Azhar et al 2018a).…”

“…This temperature range is essential in influencing plant growth stages, which once low, tends to extend the early vegetative phase. The photosynthetic activity of sago palms is more optimal at a temperature of 25-29 o C (Azhar et al 2018a)…”

ASSOCIATION OF SEED COLOUR WITH GERMINATION, PHYSICAL AND PHYSIOLOGICAL GROWTH OF OIL PALM (Elaeis guineensis) SEEDLINGS

“…Ibrahim et al (2010) reported that net photosynthesis of seven months old oil palm seedlings exposed to normal 400 ppm atmospheric CO2 level were between 15 to 20 μmol CO2 m -2 s -1 . On the other hand, lower net photosynthesis ranging from 4 to 9 μmol CO2 m -2 s -1 was shown by 12 months old sago palm (Azhar et al, 2018) and young macaw palm seedlings (Dias et al, 2018). By comparing these values from Ibrahim et al (2010) and Azhar et al (2018), it is evident that all the seed colour produces seedlings that have normal photosynthetic capacity at both pre-nursery and main nursery stages.…”

“…On the other hand, lower net photosynthesis ranging from 4 to 9 μmol CO2 m -2 s -1 was shown by 12 months old sago palm (Azhar et al, 2018) and young macaw palm seedlings (Dias et al, 2018). By comparing these values from Ibrahim et al (2010) and Azhar et al (2018), it is evident that all the seed colour produces seedlings that have normal photosynthetic capacity at both pre-nursery and main nursery stages. The increasing net photosynthesis value from three months to the remaining nine months of nursery evaluation indicates higher energy requirement of the growing seedlings (Bravdo, 1971).…”

Sago palm (Metroxylon sagu Rottb.) response to drought condition in terms of leaf gas exchange and chlorophyll a fluorescence

“…The PAM parameters were calculated with WinControl software (Walz, Effeltrich, Germany) using the standard settings for rapid light curve protocols provided by the Walz soft-ware. The measurement of light-response curve data pairs was conducted and fitted following Ritchie (2008) as described in Azhar et al (2018). ETR data was fitted using non-linear least squares model calculated as:…”