EFFECT OF AIR TEMPERATURES ON DIURNAL VARIATION OF WATER POTENTIAL, CONDUCTANCE AND CO2 ASSIMILATION OF MANGO (MANGIFERA INDICA L.) LEAVES
Diurnal variations in leaf water potential ( ), Stomatal conductance (gs) and CO2 assimilation (A) were studied in two-year-old potted mango trees cv. Nam Dok Mai. The experiment was carried out in sun-lit rooms where air temperatures were controlled at either 15/10 or 30/20°C (day/night). The soil temperature of the pots was held at 25°C and the relative humidity at 80% in each of the rooms. At both temperature regimes the greatest decrease in occurred between 0600 and 0800 h (falling from -1.0 to -1.5 MPa). Recovery of at both temperature regimes occurred between 1600 and 1800 h. At 15/10°C, gs declined from 1.2 cm s-1 at 0600 h to 0.6 cm s-1 between 1200 to 1600 h, but recovered to the dawn rates of gs by 1800 h. At 30/20°C, gs was lowest (0.5 cm s-1) at 0600 h, reached a maximum (2.4 cm s-1) at 1400 h and declined again to 1.1 cm s-1 by 1800 h. At both temperature regimes, A increased between 0800 to 1000 h. In trees grown at 15/10°C, A increased from 1.7 to 3.1 umol CO2 m-2 s-1 and at 30/20°C from 6.4 to 7.8 umol CO2 m-2 s-1 by 1000 h, where it remained relatively constant at the respective rates until 1400 h. There was a decline in A at 1600 h in both treatments which was concurrent with falling photosynthetic photon flux density. Our results show that air temperatures affected the and gas exchange of mango trees. The extent to which these changes may have affected growth and development of trees will be reported in the future.
Pongsomboon, W., Whiley, A.W., Stephenson, R.A. and Subhadrabandhu, S. (1992). EFFECT OF AIR TEMPERATURES ON DIURNAL VARIATION OF WATER POTENTIAL, CONDUCTANCE AND CO2 ASSIMILATION OF MANGO (MANGIFERA INDICA L.) LEAVES. Acta Hortic. 321, 472-481