The significance of micro-morphologica1 leaf surface characters of plants in indication and mitigation of auto-exhaust pollution has been investigated. For the purpose of the study, the following plant species growing along roadsides in low and high traffic density areas have been selected: Asparagus racemosus, Azadirachta indica, Bougainvillea spectabilis, Cassia fistula, Ficus religiosa, Nerium indicum, Polyalthia longifolia and Thevetia neriifolia. These plants were continuously exposed to automobile emissions. As compared to control plants, the leaf surface structures changed significantly in the exposed plants. The epidermal cells collapsed, cell boundaries were irregularly fused, and a two-fold increase in stomatal frequency and trichome length could be observed. Epicuticular wax also lost its original shape, got disorganised and subsequently eroded, forming patches of a crust on the cuticle. While the surface structural changes were significant, the phenology of these plants remained unaffected by auto-exhaust pollution. The investigated species though manifesting above changes remained normal and healthy and, therefore, they may be recommended for growing along roadsides in areas polluted by automobile emissions.
Epidermal (non-stomatally-controlled) conductance from the fourth leaf, first node leaf, flag leaf and ear of durum wheat (Triticum turgidum var durum L.) grown under Mediterranean field conditions has been measured, along with leaf stomatal frequency and the amount and distribution of epicuticular waxes. Measurements were carried out on varieties and land-races from the Middle East, North Africa, ‘Institut National de la Recherche Agricole’ (INRA) and ‘Centra Internacional de Mejora de Maiz y Trigo’ (CIMMYT). Significant differences were observed among genotypes in the epidermal conductances (ge) of the four organs. For each of the four organs tested, genotypes from the Middle East and CIMMYT showed higher ge. values than those from North Africa and INRA. Ears showed epidermal conductances that were more than four times higher than those of leaves when ge. values were expressed per unit dry weight. The amount of epicuticular waxes was higher in the fourth leaves, intermediate in the first node and flag leaves and lower in the ears. For each organ, ge differences among genotypes were unrelated with the amount of epicuticular waxes. Removal of epicuticular waxes by dipping the organs into chloroform significantly increased the epidermal conductance for the fourth and first node leaves and the ear. However, this did not occur for the flag leaf. For the fourth leaf, ge of intact leaves and ge of leaves in which epicuticular waxes were removed were unrelated (r = -0.265). The regression coefficient of this relation for the first node and flag leaves showed values of 0.666 and 0.650 (P > 0.05), respectively, and values were even higher in the ear (r > m 0.892, P > 0.01). Scanning electron microscope analysis showed that wax bloom decreased from the fourth leaf to the flag leaf, whereas the extent of amorphous wax increased. Wax bloom in leaves consisted mainly of deposits of thin wax plates. In the ears and the adaxial surface of flag leaves, fibrillar waxes predominated. In the first node and flag leaves, the wax deposits on the adaxial side cover the surface of the leaf more densely and uniformly than those on the abaxial side. There was no significant correlation between ge and total stomatal density, or between ge and either adaxial or abaxial stomatal density for any sample of the three different leaves. The contribution of epicuticular waxes plus total stomatal frequency only explained 42.4, 11.8, 28.3 and 16% of ge (per unit leaf area) variations for the fourth leaf, first node leaf, flag leaf and the combined variation of the three leaves together, respectively. From these results, it is concluded that complex interrelationship between different morphophysiological characteristics probably control ge differences among genotypes and that these interrelationships differ for each different plant part.
Stomata development variability of ten wheat genotypes under early water stress
Mansouri D., Neila R., Chalh A., Fethi B., El Gazzah M. (2016)
D. MANSOURI1, N. RASSAA*2, A. CHALH1 , F. BNEJDI1 , M. EL GAZZAH1
1 Laboratory of biodiversity, biotechnology and climatic change, Biologic Sciences Department, faculty of sciences, university of Tunis El Manar, Tunisia.
2 Laboratory of crop physiology, Higher School of Agriculture of El Kef, university of Jandouba, Tunisia
In Journ. New Sciences_AgriBiotech_Vol_35_05.pdf
Much is known about the physiological control of stomatal aperture to adjust water
availability. In contrast, few studies were conducted on the stomatal development control to limit water
loss. The objective of this study was to investigate stomatal density control in response to water
deprivation for ten wheat genotypes: six varieties of Durum wheat and four varieties of Bread wheat.
Three water regimes were applied. Separate statistical analysis of leaf area (LA) and stomatical density
(SD) at three leaf stages showed significant differences between Durum wheat and Bread wheat and all
varieties at each stage. Results reveled that SD increased with leaf stages. Drought reduced LA and
induced various responses in terms of SD. In another hand, tolerance indices of SD was in concordance
with results based on LA and reveled that only genotype “Mahmoudi” limited the stomatal development
in response to water loss. These findings highlight the role that could be played to stomatal development
during leaf expansion as a longer term to limit water loss from leaves. They also put the emphasis on
the variability of stomatal response between genotypes. Finally, for eventual breeding program the key
roles of SD should be considered to select better genotypes in terms of drought adaptability. Also,
Mahmoudi should be recommended as potential genotype for drought tolerance.
The results of controlled experiments showed that ozone combined with low temperatures of 10℃ induced weather-flecks in leaves of 5 flue-cured tobacco genotypes. The activity of SOD increased in ozone-injured leaves and increasing SOD activity was negatively correlated to the weather-fleck index. Activity of CAT was slightly enhanced but activity of POD decreased remarkably. Activity of antioxidant enzymes was low and hence antioxidant enzymes was high in genotypes, there was strong resistance to ozone injury. The results indicated that ozone combined with low temperatures of 10℃ markedly affected active oxygen-scavenging systems in tobacco leaves caused by an imbalance in activities of 3 antioxidant enzymes. Sharp decreases in POD activity might be one of the major reasons why leaves were injured by ozone, whereas increases in the activities both of SOD and CAT helped to protect against ozone injury.
Leaf responses to environmental conditions have been frequently described in fruit trees, but differences among cultivars have received little attention. This study shows that parameters of Farquhar’s photosynthesis and Jarvis’ stomatal conductance models differed between two apple cultivars, and examines the consequences of these differences for leaf water use efficiency. Leaf stomatal conductance (g(sw)), net CO2 assimilation rate (A(n)), respiration (R(d)) and transpiration (E) were measured during summer in 8-year-old ‘Braeburn’ and ‘Fuji’ apple trees under well-watered field conditions. Parameters of Farquhar’s and Jarvis’ models were estimated, evaluated and then compared between cultivars. Leaf carbon isotope discrimination (delta(13)C) was measured at the end of the growing season. A single positive relationship was established between V(Cmax) (maximum carboxylation rate) and N(a) (leaf nitrogen concentration per unit area), and between J(max) (maximum light-driven electron transport rate) and N(a). A higher leaf R(d) was observed in ‘Fuji’. The g(sw) responded similarly to increasing irradiance and leaf temperature in both cultivars. g(sw) responded to lower vapour pressure deficit in ‘Fuji’ than in ‘Braeburn’. Maximal conductance (g(swmax)) was significantly smaller and A(n) was more limited by g(sw) in ‘Braeburn’ than ‘Fuji’. Lower g(sw), E and higher intrinsic water use efficiency were shown in ‘Braeburn’ and confirmed by smaller leaf delta(13)C compared with ‘Fuji’ leaves. The use of functional model parameters allowed comparison of the two cultivars and provided evidence of different water use ‘strategies’: ‘Braeburn’ was more conservative in water use than ‘Fuji’, due to stomatal limitation of A(n), higher intrinsic water use efficiency and lower delta(13)C. These physiological traits need to be considered in relation to climate adaptation, breeding of new cultivars and horticultural practice.
The number of stomata and the concentration of macro- and microelements in four new winter wheat genotypes: Lenta, Lara, Perla and Fiesta were investigated in two localities in Croatia in the 1997/98 growing season.
The stomata number per mm2 was determined by a standard method. N was established by the micro-Kjeldahl method, P spectrophotometrically and K, Ca, Mg, Zn, Cu, Fe and Mn by the AAS method.
The interrelation of the investigated parameters was determined by multiple regression and correlation analysis.
The results obtained indicate that the number of stomata per mm2 and the macro- and microelement concentrations depended on the genotype, the phenophase and the locality.
A statistically significant correlation was found between the stomata number per mm2 and the macro- (N, P, K, Ca, Mg) and microelement (Zn, Cu, Fe, Mn) concentrations
This study were conducted to determine, if stomata density can be used as a criterion in cultivar differentiation or not.
In this study, density of stomatas in stipula and abaxial and adaxial surface of leaflets was determined in the flowering and pod set period of 23 pea cultivars and lines that were sowed as wintertime for 2 years.
The effect of years on the stomata density in other parts sections except for the stomata numbers in stipula and leaflet adaxial surface were determined on the level of statistical significance.
In pod setting period, stomata numbers were higher compared to the flowering period. Stomata number in leaf section of the 5 cultivars used in the trial is in general higher than those of the lines.
The determination of year x genotype interaction in the study shows that there is not enough evidence for using this characteristic for cultivar differentiation.