Photosynthetic characteristics of Hordeum, Triticum, Rumex, and Trifolium species at contrasting altitudes

Abstract

Photosynthetic characteristics were compared between plants of low altitude (LA) grown at LA (Palampur; 1 300 m) and at high altitude, HA (Kibber; 4 200 m), and plants naturally occurring at different altitudes (Palampur, 1 300 m; Palchan, 2 250 m; and Marhi, 3 250 m). Net photosynthetic rate (P N ) was not significantly different between altitudes. However, the slopes of the curve relating P N to intercellular CO 2 concentration (C i ) were higher in plants at Palchan, Marhi, and Kibber compared to those at Palampur, indicating that plants had higher efficiency of carbon uptake (the initial slope of P N /C i curve is an indication) at HA. They had also higher stomatal conductance (g s ), transpiration rate, and lower water use efficiency at HA. g s was insensitive to photosynthetic photon flux density (PPFD) for plants naturally occurring at Palampur, Palchan, and Marhi, whereas plants from LA grown at Palampur and Kibber responded linearly to increasing PPFD. Insensitivity of g s to PPFD could be one of the adaptive features allowing wider altitudinal distribution of the plants.Additional key words: intercellular CO 2 concentration; net photosynthetic rate; photosynthetic photon flux density; stomatal conductance.

Effect of Altitude on the Response of Net Photosynthetic Rate to Carbon Dioxide Increase by Spring Wheat

“…Contrary to the results of this study, Kumar et al (2005) reported no significant difference in P n of wheat and barley between altitudes 1300 m and 4200 m above sea level. They suggested that higher efficiency of carbon uptake at higher altitude resulted in similar P n at both altitudes.…”

“…The values of stomatal conductance at low altitude were 0.14-0.17 mol m -2 s -1 , which were relatively lower compared with the values in this study at 0.21-0.69 mol m -2 s -1 and other studies at 0.1-1 mol m -2 s -1 (Reynolds et al, 2000;Martínez-Carrasco et al, 2005). This suggests environmental stresses were at low altitude in the experiment by Kumar et al (2005), leading to lower stomatal conductance and P n at low altitude than at high altitude. In this study, the values of stomatal conductance in all experiments were similar to other studies (Reynolds et al, 2000;Martínez-Carrasco et al, 2005), and stomatal conductance showed no difference between altitudes.…”

“…The partial pressure of CO 2 in air decreases with increase in altitude, and its effect on photosynthesis has been of interest to plant physiologists and ecologists (Billings et al, 1961;Körner and Diemer, 1987;Friend et al, 1989;Terashima et al, 1995;Bowman et al, 1999;Sakata and Yokoi, 2002;Kumar et al, 2005). Friend et al (1989) measured the net photosynthetic rate (P n ) in Vaccinium myrtillus L. and Nardus strica L. along altitudinal gradients between 200 m and 1100 m. P n increased in both species with the increase in altitude, probably because of the increase in leaf nitrogen per unit leaf area.…”

“…Bowman et al (1999), however, observed similar levels of P n in populations of Frasera speciosa grown between 1800 m and 3500 m, and they considered that the increase in internal conductance of leaves at higher altitude results in maintenance of similar P n among populations. Kumar et al (2005) also measured photosynthetic parameters for the same varieties of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) in fi elds at elevations of 1300 m and 4200 m, and they found no difference in P n between altitudes.…”

Altitude-related changes in activities of carbon metabolism enzymes in Rumex nepalensis

“…Mountain plants evolved in response to their particular altitude environment differ in physiological response to the respective ecotypes from lowland areas (Billings et al 1961, Hiesey et al 1971, Mächler et al 1977, Körner and Diemer 1987, Cordell et al 1998, Hovenden and Schimanski 2000, Hovenden and Schoor 2003, Kumar et al 2005. However, there is little information on altitude related changes in enzymatic activities related to carbon metabolism except for enzymes such as ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO).…”