Stomatal and photosynthetic responses ofCichorium intybus leaves to sulfur dioxide treatment at different stages of plant development

Abstract

Fifty-day-old Cichorium in~/bus Linn. plants were exposed to I ppm sulfur dioxide gas, 2 h per day for 7 consecutive days. Their leaves as well as those from the conlrol plants were sampled at pre-flowerin& flowering, and post-flowering stages to study their morphological, physiological, and biochemical responses to S02 stress. The number, dimensions, area, and biomass of leaves were less in the treated plants. Length and width of stomatal apertures on both epidermises were greater for leaves exposed to S02. The Stomata were longer on the adaxial epidermis, but shorter on the abaxial epidermis, except at the pre-flowering stage. Stomatal widths varied widely. Compared with the controis, the abaxial epidermis on treated leaves showed consistently lower stomatal densities as well as stomatal indices. This was also true for the adaxial epidermis during the post-flowering stage. The photosynthetic rate and stomatal conductance were reduced in the S02-exposed plants, but intercellular CO~ concentrations increased at the pre-flowering stage and, subsequently, declined. Chlorophyll a, carotenoid, and total chlorophyll contents increased at the pre-flowering stage, and then decreased. The level of chlorophyll b was reduced throughout plant development compared with the untreated controls.

Effect of Coal Smoke Pollution on the Biomass and Chlorophyll Pigments of <i>Brassica juncea</i>

“…A marked reduction in chlorophyll pigments resulted a further reduction in the biomass of the plant were studied by a number of workers under the stress of air pollutants as in the present investigation. (Kumar 1986, Singh and Rao 1986, Malabari et al 1991, Dhir et al 2001and Wali et al 2004.The views differ on the mechanism of air pollution induced chlorophyll loss. According to Singh et al (1990a) the total chlorophyll continues to decrease with increasing Sodium Meta bisulphate (Na 2 S 2 O 3 ) concentration in tomato leaves.…”

Photosynthetic, metabolic and growth responses ofTriumfetta rhomboideato coal-smoke pollution at different stages of plant ontogeny

“…Symptoms of morphological injury usually appear when plants are exposed to higher concentration of pollutants (Rao and Rao 1989). Low levels of SO 2 do not produce any obvious morphological injury (Lone et al 1995;Williams and Banerjee 1995), but may affect photosynthetic rate and stomatal behavior, and finally the plant yield (Dhir et al 2001;Agrawal 2003). NO x may sometimes have positive effects on plant growth and yield but in combination with SO 2 , as they normally are, N oxides prove toxic to plants (Bell and Treshow 2002).…”

Anatomical and functional responses of Calendula officinalis L. to SO2 stress as observed at different stages of plant development

“…Leaves experience the maximum brunt of exposure and accordingly undergo structural and functional alterations with changing habitat environment. On reaching the mesophyll through stomata, SO 2 combines with water to form sulphurous acid, which, on dissociation, produces phytotoxic sulphite and bisulphite ions (Rennenberg and Herschbach, 1996;Rennenberg and Polle, 1994 injury, disturb stomatal behaviour and transpiration, inhibit photosynthesis and reduce the final yield (Dhir et al, 2001;Wali et al, 2004;Yunus and Iqbal, 1996).…”